1.
Torus
–
In geometry, a torus is a surface of revolution generated by revolving a circle in three-dimensional space about an axis coplanar with the circle. If the axis of revolution does not touch the circle, the surface has a shape and is called a torus of revolution. Real-world examples of objects include inner tubes, swim rings, and the surface of a doughnut. A torus should not be confused with a solid torus, which is formed by rotating a disc, rather than a circle, a solid torus is a torus plus the volume inside the torus. Real-world approximations include doughnuts, vadai or vada, many lifebuoys, in topology, a ring torus is homeomorphic to the Cartesian product of two circles, S1 × S1, and the latter is taken to be the definition in that context. It is a compact 2-manifold of genus 1, the ring torus is one way to embed this space into three-dimensional Euclidean space, but another way to do this is the Cartesian product of the embedding of S1 in the plane. This produces an object called the Clifford torus, a surface in 4-space. In the field of topology, a torus is any space that is topologically equivalent to a torus. R is known as the radius and r is known as the minor radius. The ratio R divided by r is known as the aspect ratio, a doughnut has an aspect ratio of about 2 to 3. An implicit equation in Cartesian coordinates for a torus radially symmetric about the z-axis is 2 + z 2 = r 2, or the solution of f =0, algebraically eliminating the square root gives a quartic equation,2 =4 R2. The three different classes of standard tori correspond to the three aspect ratios between R and r, When R > r, the surface will be the familiar ring torus. R = r corresponds to the torus, which in effect is a torus with no hole. R < r describes the self-intersecting spindle torus, when R =0, the torus degenerates to the sphere. When R ≥ r, the interior 2 + z 2 < r 2 of this torus is diffeomorphic to a product of an Euclidean open disc, the losses in surface area and volume on the inner side of the tube exactly cancel out the gains on the outer side. In traditional spherical coordinates there are three measures, R, the distance from the center of the system, and θ and φ. As a torus has, effectively, two points, the centerpoints of the angles are moved, φ measures the same angle as it does in the spherical system. The center point of θ is moved to the center of r and these terms were first used in a discussion of the Earths magnetic field, where poloidal was used to denote the direction toward the poles
2.
Doughnut
–
A doughnut or donut is a type of fried dough confectionery or dessert food. The doughnut is popular in countries and prepared in various forms as a sweet snack that can be homemade or purchased in bakeries, supermarkets, food stalls. Doughnuts are usually deep-fried from a dough, and typically either ring-shaped or without a hole. Other types of batters can also be used, and various toppings and flavorings are used for different types, such as sugar, chocolate, or maple glazing. In addition to flour, doughnuts may also include such ingredients as water, leavening, eggs, milk, sugar, oil/shortening, the two most common types are the ring doughnut and the filled doughnut—which is injected with fruit preserves, cream, custard, or other sweet fillings. A small spherical piece of dough may be cooked as a doughnut hole, once doughnuts have been fried, they may be glazed with a sugar icing, spread with icing or chocolate, or topped with powdered sugar or sprinkles or fruit. Other shapes include rings, balls, and flattened spheres, as well as ear shapes, twists, Doughnut varieties are also divided into cake and yeast-risen type doughnuts. Donuts are often accompanied by coffee when they are purchased at shops or fast food restaurants. This smaller piece of dough can be cooked and served as a hole or added back to the batch to make more doughnuts. A disk-shaped doughnut can also be stretched and pinched into a torus until the center breaks to form a hole, alternatively, a doughnut depositor can be used to place a circle of liquid dough directly into the fryer. There are two types of ring doughnuts, those made from a dough for raised doughnuts, or those made from a special type of cake batter. Yeast-raised doughnuts contain about 25% oil by weight, whereas cake doughnuts oil content is around 20%, cake doughnuts are fried for about 90 seconds at approximately 190 °C to 198 °C, turning once. Yeast-raised doughnuts absorb more oil because they take longer to fry, about 150 seconds, cake doughnuts typically weigh between 24 g and 28 g, whereas yeast-raised doughnuts average 38 g and are generally larger, and taller when finished. After frying, ring doughnuts are often topped, raised doughnuts are generally covered with a glaze. Cake doughnuts can also be glazed, or powdered with confectioners sugar, or covered with cinnamon and they are also often topped with cake frosting and sometimes sprinkled with coconut, chopped peanuts, or sprinkles. Doughnut holes are small, bite-sized doughnuts that were made from the dough taken from the center of ring doughnuts. Traditionally, doughnut holes are made by frying the dough removed from the portion of the doughnut. Consequently, they are smaller than a standard doughnut and tend to be spherical
3.
Rope
–
A rope is a group of yarns, plies, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting, as a result, they cannot be used for pushing or similar compressive applications. Rope is thicker and stronger than similarly constructed cord, line, string, fiber rope is made from fiber, whereas wire rope is made from wire. Rope may be constructed of any long, stringy, fibrous material, synthetic fibre ropes are significantly stronger than their natural fibre counterparts, but also possess certain disadvantages, including slipperiness. Common natural fibres for rope are manila hemp, hemp, feathers, linen, cotton, coir, jute, straw, synthetic fibres in use for rope-making include polypropylene, nylon, polyesters, polyethylene, Aramids and acrylics. Some ropes are constructed of mixtures of several fibres or use co-polymer fibres, wire rope is made of steel or other metal alloys. Ropes have been constructed of fibrous materials such as silk, wool, and hair. Rayon is a fibre used to make decorative rope. The twist of the strands in a twisted or braided rope serves not only to keep a rope together, without any twist in the rope, the shortest strand would always be supporting a much higher proportion of the total load. Rope is of paramount importance in fields as diverse as construction, seafaring, exploration, sports, theatre, and communications, to fasten rope, many types of knots have been invented for countless uses. Pulleys redirect the force to another direction, and can create mechanical advantage so that multiple strands of rope share a load. Winches and capstans are machines designed to pull ropes, such ropes normally use a kernmantle construction, as described below. Static ropes, used for example in caving, rappelling, and rescue applications, are designed for minimal stretch, the UIAA, in concert with the CEN, sets climbing-rope standards and oversees testing. Any rope bearing a GUIANA or CE certification tag is suitable for climbing, climbing ropes, however, do cut easily when under load. Keeping them away from sharp rock edges is imperative, rock climbing ropes come with either a designation for single, double or twin use. A single rope is the most common and it is intended to be used by itself, single ropes range in thickness from roughly 9mm to 11mm. Smaller ropes are lighter, but wear out faster, double ropes are thinner ropes, usually 9mm and under, and are intended for use as a pair. These ropes offer a margin or security against cutting, since it is unlikely that both ropes will be cut, but they complicate belaying and leading
4.
Curve
–
In mathematics, a curve is, generally speaking, an object similar to a line but that need not be straight. Thus, a curve is a generalization of a line, in that curvature is not necessarily zero, various disciplines within mathematics have given the term different meanings depending on the area of study, so the precise meaning depends on context. However, many of these meanings are special instances of the definition which follows, a curve is a topological space which is locally homeomorphic to a line. In everyday language, this means that a curve is a set of points which, near each of its points, looks like a line, a simple example of a curve is the parabola, shown to the right. A large number of curves have been studied in multiple mathematical fields. A closed curve is a curve that forms a path whose starting point is also its ending point—that is, closely related meanings include the graph of a function and a two-dimensional graph. Interest in curves began long before they were the subject of mathematical study and this can be seen in numerous examples of their decorative use in art and on everyday objects dating back to prehistoric times. Curves, or at least their graphical representations, are simple to create, historically, the term line was used in place of the more modern term curve. Hence the phrases straight line and right line were used to distinguish what are called lines from curved lines. For example, in Book I of Euclids Elements, a line is defined as a breadthless length, Euclids idea of a line is perhaps clarified by the statement The extremities of a line are points. Later commentators further classified according to various schemes. For example, Composite lines Incomposite lines Determinate Indeterminate The Greek geometers had studied many kinds of curves. One reason was their interest in solving problems that could not be solved using standard compass. These curves include, The conic sections, deeply studied by Apollonius of Perga The cissoid of Diocles, studied by Diocles, the conchoid of Nicomedes, studied by Nicomedes as a method to both double the cube and to trisect an angle. The Archimedean spiral, studied by Archimedes as a method to trisect an angle, the spiric sections, sections of tori studied by Perseus as sections of cones had been studied by Apollonius. A fundamental advance in the theory of curves was the advent of analytic geometry in the seventeenth century and this enabled a curve to be described using an equation rather than an elaborate geometrical construction. Previously, curves had been described as geometrical or mechanical according to how they were, or supposedly could be, conic sections were applied in astronomy by Kepler. Newton also worked on an example in the calculus of variations
5.
Compression (physics)
–
It is contrasted with tension or traction, the application of balanced outward forces, and with shearing forces, directed so as to displace layers of the material parallel to each other. The compressive strength of materials and structures is an important engineering consideration, in uniaxial compression the forces are directed along one direction only, so that they act towards decreasing the objects length along that direction. If the stress vector itself is opposite to x, the material is said to be under compression or pure compressive stress along x. In a solid, the amount of compression depends on the direction x. If the stress vector is purely compressive and has the same magnitude for all directions and this is the only type of static compression that liquids and gases can bear. In a mechanical longitudinal wave, or compression wave, the medium is displaced in the waves direction, when put under compression, every material will suffer some deformation, even if imperceptible, that causes the average relative positions of its atoms and molecules to change. The deformation may be permanent, or may be reversed when the compression forces disappear, in the latter case, the deformation gives rise to reaction forces that oppose the compression forces, and may eventually balance them. Liquids and gases cannot bear steady uniaxial or biaxial compression, they will deform promptly and permanently, however they can bear isotropic compression, and may be compressed in other ways momentarily, for instance in a sound wave. The deformation may not be uniform and may not be aligned with the compression forces, what happens in the directions where there is no compression depends on the material. Most materials will expand in those directions, but some special materials will remain unchanged or even contract, by inducing compression, mechanical properties such as compressive strength or modulus of elasticity, can be measured. Compression machines range from small table top systems to ones with over 53 MN capacity. Gases are often stored and shipped in highly compressed form, to save space, slightly compressed air or other gases are also used to fill balloons, rubber boats, and other inflatable structures. Compressed liquids are used in equipment and in fracking. In internal combustion engines the explosive mixture gets compressed before it is ignited, in the Otto cycle, for instance, the second stroke of the piston effects the compression of the charge which has been drawn into the cylinder by the first forward stroke. This compression, moreover, obviates the shock which would otherwise be caused by the admission of the steam for the return stroke. Buckling Container compression test Compression member Compressive strength Longitudinal wave P-wave Rarefaction Strength of materials
6.
Line (geometry)
–
The notion of line or straight line was introduced by ancient mathematicians to represent straight objects with negligible width and depth. Lines are an idealization of such objects, the straight line is that which is equally extended between its points. In modern mathematics, given the multitude of geometries, the concept of a line is tied to the way the geometry is described. When a geometry is described by a set of axioms, the notion of a line is left undefined. The properties of lines are determined by the axioms which refer to them. One advantage to this approach is the flexibility it gives to users of the geometry, thus in differential geometry a line may be interpreted as a geodesic, while in some projective geometries a line is a 2-dimensional vector space. This flexibility also extends beyond mathematics and, for example, permits physicists to think of the path of a light ray as being a line, to avoid this vicious circle certain concepts must be taken as primitive concepts, terms which are given no definition. In geometry, it is frequently the case that the concept of line is taken as a primitive, in those situations where a line is a defined concept, as in coordinate geometry, some other fundamental ideas are taken as primitives. When the line concept is a primitive, the behaviour and properties of lines are dictated by the axioms which they must satisfy, in a non-axiomatic or simplified axiomatic treatment of geometry, the concept of a primitive notion may be too abstract to be dealt with. In this circumstance it is possible that a description or mental image of a notion is provided to give a foundation to build the notion on which would formally be based on the axioms. Descriptions of this type may be referred to, by some authors and these are not true definitions and could not be used in formal proofs of statements. The definition of line in Euclids Elements falls into this category, when geometry was first formalised by Euclid in the Elements, he defined a general line to be breadthless length with a straight line being a line which lies evenly with the points on itself. These definitions serve little purpose since they use terms which are not, themselves, in fact, Euclid did not use these definitions in this work and probably included them just to make it clear to the reader what was being discussed. In an axiomatic formulation of Euclidean geometry, such as that of Hilbert, for example, for any two distinct points, there is a unique line containing them, and any two distinct lines intersect in at most one point. In two dimensions, i. e. the Euclidean plane, two lines which do not intersect are called parallel, in higher dimensions, two lines that do not intersect are parallel if they are contained in a plane, or skew if they are not. Any collection of many lines partitions the plane into convex polygons. Lines in a Cartesian plane or, more generally, in affine coordinates, in two dimensions, the equation for non-vertical lines is often given in the slope-intercept form, y = m x + b where, m is the slope or gradient of the line. B is the y-intercept of the line, X is the independent variable of the function y = f
7.
Tension (physics)
–
Tension is the opposite of compression. At the atomic level, when atoms or molecules are pulled apart each other and gain potential energy with a restoring force still existing. Each end of a string or rod under such tension will pull on the object it is attached to, to restore the string/rod to its relaxed length. In physics, tension, as a force, as an action-reaction pair of forces. The ends of a string or other object transmitting tension will exert forces on the objects to which the string or rod is connected and these forces due to tension are also called passive forces. Tension in a string is a scalar quantity. A string or rope is often idealized as one dimension, having length but being massless with zero cross section. If there are no bends in the string, as occur with vibrations or pulleys, then tension is a constant along the string, by Newtons Third Law, these are the same forces exerted on the ends of the string by the objects to which the ends are attached. If the string curves around one or more pulleys, it still have constant tension along its length in the idealized situation that the pulleys are massless and frictionless. A vibrating string vibrates with a set of frequencies that depend on the strings tension and these frequencies can be derived from Newtons laws of motion. Each microscopic segment of the string pulls on and is pulled upon by its neighboring segments, tension = τ where x is the position along the string. If the string has curvature, then the two pulls on a segment by its two neighbors will not add to zero, and there will be a net force on that segment of the string, causing an acceleration. With solutions that include the various harmonics on a stringed instrument, tension is also used to describe the force exerted by the ends of a three-dimensional, continuous material such as a rod or truss member. Such a rod elongates under tension, a system is in equilibrium when the sum of all forces is zero. ∑ F → =0 For example, consider a system consisting of an object that is being lowered vertically by a string with tension, T, at a constant velocity. ∑ F → = T → + m g → =0 A system has a net force when a force is exerted on it. Acceleration and net force always exist together, ∑ F → ≠0 For example, consider the same system as above but suppose the object is now being lowered with an increasing velocity downwards therefore there exists a net force somewhere in the system. In this case, negative acceleration would indicate that | m g | > | T |
8.
Hoist (device)
–
A hoist is a device used for lifting or lowering a load by means of a drum or lift-wheel around which rope or chain wraps. It may be operated, electrically or pneumatically driven and may use chain. The load is attached to the hoist by means of a lifting hook, the basic hoist has two important characteristics to define it, Lifting medium and power type. The lifting medium is either wire rope, wrapped around a drum, or load-chain, the power can be provided by different means. Common means are hydraulics, electrical and air driven motors, both the wire rope hoist and chain hoist have been in common use since the 1800s, however mass production of an electric hoist did not start until the early 1900s and was first adapted by Germany. A hoist can be built as one unit, designed for cost-effective purchasing and moderate use, or it can be built as a built-up custom unit, designed for durability. The built-up hoist will be more expensive, but will also be easier to repair. Package units were regarded as being designed for light to moderate usage. Built-up units are designed for heavy to severe service, but over the years that market has decreased in size since the advent of the more durable packaged hoist. A machine shop or fabricating shop will use an integral-package hoist, while a Steel Mill or NASA would use a unit to meet durability, performance. NASA has also seen a change in the use of package hoists, the NASA Astronaut training pool, for example, utilizes cranes with packaged hoists. The more commonly used hoist in todays worldwide market is an electrically powered hoist and these are either the chain type or the wire rope type. See the Hoists Manufacturers Institute site for true life calculation which is based on load, in todays modern world for the North American market there are a few governing bodies for the industry. The Overhead Alliance is a group that represents Crane Manufacturers Association of America, Hoist Manufacturers Institute and these product counsels of the Material Handling Industry of America have joined forces to create promotional materials to raise the awareness of the benefits to overhead lifting. The members of group are marketing representatives of the member companies. Common small portable hoists are of two types, the chain hoist or chain block and the wire rope or cable type. Chain hoists may have a lever to actuate the hoist or have a loop of operating chain that one pulls through the block which then activates the block to take up the main lifting chain. For a given rated load wire rope is lighter in weight per unit length, the lift chain of a chain hoist is far larger than the liftwheel over which chain may function
9.
Bicycle lock
–
A bicycle lock is a security device used to deter bicycle theft, generally by fastening the bicycle to a fixed object, e. g. a bike rack. Quick-release levers - common on most bicycle wheels and seatpost fasteners - are a challenge for theft preventions. Unless both wheels and frame are secured, wheels can be removed separately, an optimal locking method will secure the frame as well as both wheels — either to a fixed object or to each other. Locking devices vary in size and security, the most secure tending to be the largest, heaviest and least portable, thus, like other security equipment, bicycle lockers must balance the competing interests of security, portability, and cost. Some are made of expensive materials chosen for their acceptable strength. An alternate defense is the provision of bicycle lockers or a cage in which the whole bicycle is locked. A bike locker is not a bicycle lock, test standards that rate the effective security of bicycle locks are provided by Thatcham and Sold Secure in the United Kingdom, ART in the Netherlands, SSF in Sweden, and VDS in Germany. A U-lock is a metal ring in the shape of the letter U. The U part of the lock attaches to a crossbar section, to lock the bicycle, one locks it physically to some other object, such as a bike rack, parking meter or other pole installed securely in the solid ground. Merely locking the frame to the wheel is not recommended because, although it cannot be rolled away. U-locks are more secure than most other kinds of locking mechanism because they are resistant to cutting with high-leverage hand tools such as bolt cutters. However, most are still vulnerable to at least one type of exploit, for instance, if there is enough space for a thief to fit a jack into the U, the jack can produce enough leverage to break the lock. Another common brute force method to break open U-locks is to use a length of pipe to twist the lock open. Like all locks, U-Locks are vulnerable to power such as portable angle grinders. A quality U-lock will advertise the materials hardness, its resistance to prying, for a time, many U-locks used a cylindrical pin tumbler lock. However, most cylindrical locks can be picked by thieves using a common disposable Bic pen, U-locks with cylindrical pin tumblers should be avoided, though most manufacturers no longer offer them. A very similar type of lock, often referred to as an O-lock and this lock may be more protective as it does not leave space for thieves to insert tools like a car jack which would burst a normal u-lock. A chain lock is a chain with a lock and it often has a key or a combination lock attached to it
10.
Dimension
–
In physics and mathematics, the dimension of a mathematical space is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one only one coordinate is needed to specify a point on it – for example. The inside of a cube, a cylinder or a sphere is three-dimensional because three coordinates are needed to locate a point within these spaces, in classical mechanics, space and time are different categories and refer to absolute space and time. That conception of the world is a space but not the one that was found necessary to describe electromagnetism. The four dimensions of spacetime consist of events that are not absolutely defined spatially and temporally, Minkowski space first approximates the universe without gravity, the pseudo-Riemannian manifolds of general relativity describe spacetime with matter and gravity. Ten dimensions are used to string theory, and the state-space of quantum mechanics is an infinite-dimensional function space. The concept of dimension is not restricted to physical objects, high-dimensional spaces frequently occur in mathematics and the sciences. They may be parameter spaces or configuration spaces such as in Lagrangian or Hamiltonian mechanics, in mathematics, the dimension of an object is an intrinsic property independent of the space in which the object is embedded. This intrinsic notion of dimension is one of the ways the mathematical notion of dimension differs from its common usages. The dimension of Euclidean n-space En is n, when trying to generalize to other types of spaces, one is faced with the question what makes En n-dimensional. One answer is that to cover a ball in En by small balls of radius ε. This observation leads to the definition of the Minkowski dimension and its more sophisticated variant, the Hausdorff dimension, for example, the boundary of a ball in En looks locally like En-1 and this leads to the notion of the inductive dimension. While these notions agree on En, they turn out to be different when one looks at more general spaces, a tesseract is an example of a four-dimensional object. The rest of this section some of the more important mathematical definitions of the dimensions. A complex number has a real part x and an imaginary part y, a single complex coordinate system may be applied to an object having two real dimensions. For example, an ordinary two-dimensional spherical surface, when given a complex metric, complex dimensions appear in the study of complex manifolds and algebraic varieties. The dimension of a space is the number of vectors in any basis for the space. This notion of dimension is referred to as the Hamel dimension or algebraic dimension to distinguish it from other notions of dimension
11.
Jewellery
–
Jewellery or jewelry consists of small decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, and bracelets. Jewellery may be attached to the body or the clothes, for many centuries metal, often combined with gemstones, has been the normal material for jewellery, but other materials such as shells and other plant materials may be used. It is one of the oldest type of archaeological artefact – with 100, historically, the most widespread influence on jewellery in terms of design and style have come from Asia. Jewellery may be made from a range of materials. Gemstones and similar such as amber and coral, precious metals, beads, and shells have been widely used. In most cultures jewellery can be understood as a symbol, for its material properties, its patterns. Jewellery has been made to nearly every body part, from hairpins to toe rings. The word jewellery itself is derived from the jewel, which was anglicised from the Old French jouel. In British English, Indian English, New Zealand English, Hiberno-English, Australian English, both are used in Canadian English, though jewelry prevails by a two to one margin. Numerous cultures store wedding dowries in the form of jewellery or make jewellery as a means to store or display coins, alternatively, jewellery has been used as a currency or trade good, an example being the use of slave beads. Many items of jewellery, such as brooches and buckles, originated as functional items. Jewellery can also symbolise group membership or status, wearing of amulets and devotional medals to provide protection or ward off evil is common in some cultures. These may take the form of symbols, stones, plants, animals, body parts, in creating jewellery, gemstones, coins, or other precious items are often used, and they are typically set into precious metals. Alloys of nearly every metal known have been encountered in jewellery, bronze, for example, was common in Roman times. Modern fine jewellery usually includes gold, white gold, platinum, palladium, titanium, most contemporary gold jewellery is made of an alloy of gold, the purity of which is stated in karats, indicated by a number followed by the letter K. American gold jewellery must be of at least 10K purity, many whimsical fashions were introduced in the extravagant eighteenth century. Cameos that were used in connection with jewellery were the attractive trinkets along with many of the objects such as brooches, ear-rings. Some of the necklets were made of pieces joined with the gold chains were in and bracelets were also made sometimes to match the necklet
12.
Sprocket
–
A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh with a chain, track or other perforated or indented material. The name sprocket applies generally to any wheel upon which radial projections engage a chain passing over it and it is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth. Early automobiles were also driven by sprocket and chain mechanism. Sprockets are of designs, a maximum of efficiency being claimed for each by its originator. Sprockets typically do not have a flange, some sprockets used with timing belts have flanges to keep the timing belt centered. They can be run at speed and some forms of chain are so constructed as to be noiseless even at high speed. In the case of bicycle chains, it is possible to modify the overall ratio of the chain drive by varying the diameter of the sprockets on each side of the chain. This is the basis of derailleur gears, a multi-speed bicycle, by providing two or three different-sized driving sprockets and up to 11 different-sized driven sprockets, allows up to 33 different gear ratios. The resulting lower gear ratios make the easier to pedal up hills while the higher gear ratios make the bike more powerful to pedal on flats. In a similar way, manually changing the sprockets on a motorcycle can change the characteristics of acceleration, there may also be a third sprocket, elevated, driving the track. Sprockets are used in the transport mechanisms of movie projectors. In this case, the sprocket wheels engage film perforations in the film stock, sprocket feed was also used for punched tape and is used for paper feed to some computer printers. Roller chain Rack and pinion Toothed belt Gear train Gear ratio Chain drive Bicycle chain Mechanical advantage Chain Engagement with Sprockets
13.
Roller chain
–
It consists of a series of short cylindrical rollers held together by side links. It is driven by a wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission, though Hans Renold is credited with inventing the roller chain in 1880, sketches by Leonardo da Vinci in the 16th century show a chain with a roller bearing. There are actually two types of links alternating in the roller chain. The first type is inner links, having two inner plates held together by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the type, the outer links. This has the advantage of removing one step in assembly of the chain, the roller chain design reduces friction compared to simpler designs, resulting in higher efficiency and less wear. This problem was solved by the development of bushed chains. This distributed the wear over an area, however the teeth of the sprockets still wore more rapidly than is desirable. There is even very low friction, as long as the chain is sufficiently lubricated, continuous, clean, lubrication of roller chains is of primary importance for efficient operation as well as correct tensioning. Many driving chains operate in environments, and thus the wearing surfaces are safe from precipitation and airborne grit. Some roller chains are designed to have built into the space between the outside link plate and the inside roller link plates. Chain manufacturers began to include this feature in 1971 after the application was invented by Joseph Montano while working for Whitney Chain of Hartford, Connecticut. O-rings were included as a way to improve lubrication to the links of power transmission chains and these rubber fixtures form a barrier that holds factory applied lubricating grease inside of the pin and bushing wear areas. Further, the rubber o-rings prevent dirt and other contaminants entering the inside of the chain linkages. There are also many chains that have to operate in dirty conditions, examples include chains on farm equipment, bicycles, and chain saws. Chains operating at speeds comparable to those on motorcycles should be used in conjunction with an oil bath. For modern motorcycles this is not possible, and most motorcycle chains run unprotected, thus, motorcycle chains tend to wear very quickly relative to other applications
14.
Maillon
–
A maillon, maillon rapide or quick link is a metal link, similar to a carabiner. Maillons have a sleeve which tightens over a thread, as opposed to a hinged gate like a carabiner, making them stronger. The word maillon comes from the French language, meaning link, maillons are used primarily in climbing and caving. In caving, they are used to secure and vital connections such as those required when using single rope technique. In climbing, they are used to construct leave-in-place abseil anchors, maillons can also be used for fastening harnesses with a dual attachment point. The length of the opening, and of the maillon itself. Suppliers typically have a short and long oval in their range, D maillon, the central component of a caving harness or single rope technique kit on which all items of equipment are attached. So called because it is shaped like the letter D, delta maillon, a variation of the D maillon, the delta maillon is triangular in shape, rather than semi-circular
15.
Carabiner
–
A carabiner or karabiner is a specialized type of shackle, a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notably in safety-critical systems. The word is a form of Karabinerhaken, a German phrase for a spring hook used by a carbine rifleman, or carabinier. The carabiner has been improved several times over the decades, making it more lightweight and they are predominantly made from both steel and aluminium. Those used in sports tend to be of a lighter weight than those used in commercial applications, often referred to as carabiner-style or as mini-biners, carabiner keyrings and other light-use clips of similar style and design have also become popular. Most are stamped with a “Not For Climbing” or similar warning due to a lack of load-testing. Carabiners on hot air balloons are used to connect the envelope to the basket and are rated at 2.5 tonne,3 tonne or 4 tonne, load-bearing screw-gate carabiners are used to connect the divers umbilical to the surface supplied divers harness. They are usually rated for a working load of 5 kN or more. Carabiners come in four shapes, Oval, Symmetric. Smooth regular curves are gentle on equipment and allow easy repositioning of loads and their greatest disadvantage is that a load is shared equally on both the strong solid spine and the weaker gated axis. D, Asymmetric shape transfers the majority of the load onto the spine, offset-D, Variant of a D with a greater asymmetry, allowing for a wider gate opening. Pear/HMS, Specialized oversized offset-Ds used in belaying and these are usually the heaviest carabiners. There are three categories of carabiner, auto locking, manual locking, and non-locking. Non-locking carabiners have a swinging gate that accepts a rope, webbing sling. Rock climbers frequently connect two non-locking carabiners with a length of nylon web to create a quickdraw. Three gate types are common, Straight gate, The most utilitarian, wire gate, The lightest type, with a strength roughly equal to the others, allowing more to be carried for a given weight. Wire gates are less prone to icing up than solid gates, life supporting carabiners such as those used in tree climbing need to be strong, but also secure against unintentional opening under use. All carabiners with a spring loaded gate are self closing, several are also self locking, some even self double locking. Locking carabiners have the general shape as non-locking carabiners but have an additional mechanism securing the gate
16.
Clevis fastener
–
A clevis fastener is a three-piece fastener system consisting of a clevis, clevis pin, and tang. The clevis is a U-shaped piece that has holes at the end of the prongs to accept the clevis pin, the clevis pin is similar to a bolt, but is only partially threaded or unthreaded with a cross-hole for a split pin. The tang is a piece that fits in the space within the clevis and is held in place by the clevis pin. The combination of a simple clevis fitted with a pin is called a shackle, although a clevis. Clevises are used in a variety of fasteners used in farming equipment and sailboat rigging, as well as the automotive, aircraft. They are also used to attach control surfaces and other accessories to servo controls in airworthy model aircraft. As a part of a fastener, a provides a method of allowing rotation in some axes while restricting rotation in others. There are two types of clevis pins, threaded and unthreaded. Unthreaded clevis pins have a head at one end and a cross-hole at the other end. A cotter pin or split pin is used to keep the pin in place. Threaded clevis pins have a threaded shank on one end. The formed head has a lip, which acts as a stop when threading the pin into the shackle, the flattened tab allows for easy installation of the pin and the cross-hole allows the pin to be moused. A bolt can function as a pin, but a bolt is not intended to take the lateral stress that a clevis pin must handle. Normal bolts are manufactured to handle tension loads, whereas clevis pins, clevis pins should be closely fitted to the holes in the clevis to limit wear and reduce the failure rate of either the pin or the clevis. A twist shackle provides a loop at an angle to the axis of rotation. Older farming implements intended to be pulled by a team of animals often require a twist shackle to be hitched. A clevis hanger consists of one U-shaped clevis and a second V-shaped clevis with a hole in a section at the base of the V. Clevis hangers are used as a pipe attachment providing vertical adjustment for pipes, a clevis bracket generally takes the form of a solid metal piece with a flat rectangular base, fitted with holes for bolts or machine screws, and two rounded wings in parallel forming a clevis
17.
Hudson River Chain
–
These defenses along the Hudson River were overseen by the Highlands Department of the Continental Army. The most significant and successful was the Great Chain, constructed from West Point in 1778, the huge links for the chains were forged at iron works in Orange County, New York. Both the Americans and British knew that passage on the Hudson River was strategically important to the war effort. Americans worked to devise plans to slow or block ship passage on the river, planning to attack ships by cannons. The largest and most important project was the chain at West Point. Creating more obstructions on the river enabled the shore batteries to work their cannons against the enemy, the logs were intended to pierce and sink any British ships that passed over it. An opening was left for the passage of American ships, after the British learned of the opening from a local resident, they successfully passed through the barrier several times. The British captured Fort Washington on November 16,1776 and Fort Lee on November 20, Fort Clinton had been built just south of Popolopens Kill and also on the West Bank. In November 1776, a faulty link broke under stress induced by the river tides, after the British captured forts Montgomery and Clinton on October 6,1777, they dismantled the chain and raided upriver as far as Kingston. Governor Clinton, one of the committee assigned by the New York Convention to devise means of defending the Hudson, was heartened as the British never attempted to run ships through the chain and he concluded that the basic idea of obstructing the river seemed sound. After Captain Machin recovered from wounds from battle with the British, he work on the stronger Great Chain at West Point. Another chevaux-de-frise was constructed across the Hudson between Plum Point and Pollepel Island, north of West Point, the defenses were never fully completed, and its importance was overshadowed by completion of the Great Chain at West Point the following year. In the spring of 1778, a heavy chain supported by logs was stretched across the Hudson from West Point to Constitution Island. It was constructed at the Stirling Iron Works, in Warwick, Orange County, the task was completed in six weeks. The Hudson Rivers narrow width and sharp turns at West Point created adverse sailing conditions, the Army took advantage of this by constructing The Great Chain in 1778 as an obstacle to the movement of British ships north of West Point. The distinctive S-Curve of the Hudson at this point forced any large ship to tack in order to navigate it, American soldiers positioned the chain to impede the progress of a ship should it attempt to turn into the east-west channel against the strong current and frequently unfavorable winds. Part of the estuary of the Lower Hudson River, this area is subject to significant tides, cannons were placed in forts and artillery batteries on both sides of the river to destroy ships when they slowed to a halt against the obstacle. When finally completed, the 600 yards chain contained huge iron links, the links were carted to New Windsor, where they were put together, and floated down the river to West Point on logs late in April
18.
Livery collar
–
A livery collar or chain of office is a collar or heavy chain, usually of gold, worn as insignia of office or a mark of fealty or other association in Europe from the Middle Ages onwards. One of the oldest and best-known livery collars is the Collar of Esses, various forms of livery were used in the Middle Ages to denote attachment to a great person by friends, servants, and political supporters. From the collar hung a badge or device indicating the person the livery related to, equally gold collars that had no livery connotations were worn. Livery collars seem to be first recorded in the 14th century, the collar of Esses is first recorded earlier than this, as being given by John of Gaunt, and remained in use by the House of Lancaster throughout the Wars of the Roses. The same collar was worn by Henry IV on the way to his crowning, the inventory shows that Queen Annes collar, was made up of sprigs of rosemary garnished with pearls. The York collar had falcons and fetterlocks, and the Lancaster collar was doubtless that Collar of Esses used by the son, Henry of Bolingbroke, as an earl, duke. The oldest effigy bearing it is that in Spratton church of Sir John Swynford, who died in 1371. Swynford was a follower of John of Gaunt, and the date of his death easily disposes of the theory that the Esses were devised by Henry IV to stand for his motto or word of Soverayne. Many explanations are given of the origin of these letters, in one of Henry VIs own collars the S was joined to the broomcod of the French device, symbolizing the kings claim to the two kingdoms. The kings of the house of York and their chief followers wore the Yorkist collar of suns and roses, with the lion of March. It was presented to ministers and courtiers, and came to represent more a symbol of office by the time of Elizabeth I, the term Collar of SS was preferred by Victorian antiquaries. Since World War II, as SS is usually associated with the Schutzstaffel, besides these royal collars, the 14th and 15th centuries show many private devices. A monumental brass at Mildenhall shows a knight whose badge of a dog or wolf circled by a crown hangs from a collar with edges suggesting a pruned bough or the ragged staff. The Elizabethan artist Nicholas Hilliard was both a goldsmith and miniaturist, and so produced the whole of pieces like the Armada Jewel, given by Queen Elizabeth I of England to a courtier. When the Earl of Rutland returned from an embassy to Denmark, sixteen members of his party were given chains of gold with the James I of Englands picture, during the sixteenth century collars became marks of a specific office or Order, and subsequently remained so. Most British and Irish mayors wear a collar/chain of office, the mayors spouse may have a much smaller version. These are worn over normal clothes when on official duties, following British practice, most Canadian, Australian and New Zealand mayors also wear chains of office. Collars of various devices are worn by the knights of some of the European orders of knighthood
19.
Jewellery chain
–
Fine metal chains are used in jewellery to encircle parts of the body, namely the neck, wrists and ankles, and they also serve as points to hang decorative charms and pendants. Unlike industrial or chains for other purposes, jewellery chains or body chains are designed for aesthetic purposes, jewellery chains are typically made from precious metals, mainly gold and silver. Platinum, palladium and steel may also be used and these metals are used because they are not very reactive, keep both their intricate shape and their strength, and require only minimal maintenance to keep their shine. Small lever mechanisms called findings serve as fastenings to enable the chain to be undone and redone, belcher, This is similar to the trace, a belcher chain link is wider than its thickness. Generally the links are round, but the shape of the link can vary, curb, A curb chain is when the links interlock with each other when laid flat. Some more open-link curb chains can only be distinguished from a trace by this method and this style of chain has the greatest variety of widths available, from a few millimetres to over four centimetres. Prince Of Wales, This chain consists of a chain made of small circular links. Spiga, Spiga is formed of small figure-eight links which form a 3D chain that feels almost square, anchor, The anchor chain copies the style of the chain that holds large anchors on ships, an oval link with a dividing bar through the middle. The interlinking sections may be of a curb or trace style, Also a version called Maritime where only every other link is an anchor link. Snake, Snake chain is a very tight-linked chain that has a round or square cross-section and has links that create a slight zigzag look, herringbone, This chain that has the greatest liquid effect, formed from v-shaped links to lie entirely flat. One side can be engraved for greater aesthetics, and thin strands of herringbone can be twisted or even plaited together, briolette, Also known as Box, briolette is similar to a belcher chain except the links are tighter together and are square in shape, hence the name. Bead, Bead chain is formed of small balls of metal joined by small lengths of wire, Also has its own snap over the first link fastening. Larger steel versions are often used to hold ID cards than in jewellery. Fancy, A fancy chain can be anything, any form of metal that can be replicated and joined onto each other to make a chain. Many fancy chains are variations of the styles, for example a trace chain formed of heart-shaped links or a curb chain with every other link set with a gemstone
20.
Bicycle chain
–
A bicycle chain is a roller chain that transfers power from the pedals to the drive-wheel of a bicycle, thus propelling it. Most bicycle chains are made from carbon or alloy steel. Obsolete chain designs previously used on bicycles included the chain, the skip-link chain. The first chains were of a simple, bushingless design and these had inherent reliability problems and a bit more friction than modern chains. With these limitations in mind, the Nevoigt brothers, of the German Diamant Bicycle Company, designed the roller chain in 1898, which uses bushings, and it is the prevalent chain today. Whether it be singlespeed, fixed gear (such as track bikes and modern urban fixies, or multi-speeds with derailleurs, early examples of chain-driven bicycles include the 1869 Guilmet and Meyer, the 1879 Lawson, the 1884 McCammon, the 1884 Starley Rover, and the 1895 Diamant. Various linkage mechanisms were invented to raise the gear ratio. A bicycle chain can be energy efficient, one study reported efficiencies as high as 98. 6%. The study, performed in a laboratory environment, found that efficiency was not greatly affected by the state of lubrication. A larger sprocket will give an efficient drive, because moves the point of pressure farther away from the axle, placing less stress on the bearings. Higher chain tension was found to be efficient, This is actually not in the direction youd expect. How best to lubricate a bicycle chain is a debated question among cyclists. Liquid lubricants penetrate to the inside of the links and are not easily displaced, dry lubricants, often containing wax or Teflon, are transported by an evaporating solvent, and stay cleaner in use. The cardinal rule for long life is never to lubricate a dirty chain. Chains should be cleaned before lubrication, the chain should be wiped dry after the lubricant has had enough time to penetrate the links. An alternative approach is to change the very frequently, then proper care is less important. Some utility bicycles have fully enclosing chain guards, which virtually eliminate chain wear, on recumbent bicycles the chain is often run through tubes to prevent it from picking up dirt, and to keep the cyclists leg free from oil and dirt. On most upright bicycles, the chain loops through the rear triangle made by the right chain stay
21.
Chain drive
–
Chain drive is a way of transmitting mechanical power from one place to another. It is often used to power to the wheels of a vehicle. It is also used in a variety of machines besides vehicles. The gear is turned, and this pulls the chain putting mechanical force into the system, another type of drive chain is the Morse chain, invented by the Morse Chain Company of Ithaca, New York, United States. Sometimes the power is output by simply rotating the chain, which can be used to lift or drag objects, in other situations, a second gear is placed and the power is recovered by attaching shafts or hubs to this gear. By varying the diameter of the input and output gears with respect to each other, for example, when the bicycle pedals gear rotate once, it causes the gear that drives the wheels to rotate more than one revolution. The oldest known application of a chain appears in the Polybolos. Two flat-linked chains were connected to a windlass, which by winding back and it is here that the flat-link chain, often attributed to Leonardo da Vinci, actually made its first appearance. The chain drive itself was given power via the works of Sus water clock tank and waterwheel. Roller chain and sprockets is an efficient method of power transmission compared to belts. Although chains can be stronger than belts, their greater mass increases drive train inertia. Drive chains are most often made of metal, while belts are often rubber, plastic, urethane, or other substances. Drive belts can slip unless they have teeth, which means that the side may not rotate at a precise speed. Wear on rubber or plastic belts and their teeth is often easier to observe, one problem with roller chains is the variation in speed, or surging, caused by the acceleration and deceleration of the chain as it goes around the sprocket link by link. It starts as soon as the line of the chain contacts the first tooth of the sprocket. This contact occurs at a point below the circle of the sprocket. As the sprocket rotates, the chain is raised up to the circle and is then dropped down again as sprocket rotation continues. This rising and falling of the line is what causes chordal effect or speed variation
22.
Chain gun
–
Chain gun is a registered trademark of Orbital ATK for externally-powered machine guns. Reliability and controllability are the advantages of chain-driven weapons over their recoil-actuated counterparts, one link of the chain is connected to the bolt assembly, moving it back and forth to load, fire, extract, and eject cartridges. A misfired round does not stop the functioning of the weapon, as it might with guns that use energy from a cartridge to load the next round. During each full cycle of four periods, two periods control the time that the bolt takes to drive forward and load a round into the chamber, and how quickly it extracts it. For example, the 7. 62mm NATO version EX-34 was advertised to offer 570 rounds per minute, in practice, chain guns usually have two or three set firing speeds. The chain gun operating principle is inherently reliable and it is significant that during firing of 101,343 rounds not one jam or stoppage occurred due to loss of round control in the gun or feeder mechanism. Is in our experience very unusual in any weapon of any caliber or type, a commonly used chain gun is the M242 Bushmaster. Versions of its 25 mm action are found on ships and infantry fighting vehicles around the world. Others are the 30 mm M230 cannon, which is standard equipment on the AH-64 Apache helicopter, as well as the Bushmaster II30 mm, and the Bushmaster III 35/50 mm chain gun. A7. 62×51mm NATO caliber chain gun is used on armored vehicles as a coaxial machine gun. A developmental version of this gun was named EX-34 and it is in use as the L94A1 chain gun with the British Army. A chain gun has a barrel, while a Gatling gun/Minigun has several rotating barrels. Polybolos, a similar ancient derivative of the ballista U. S. Army Field Manual 3-22.1 Alliant Techsystems Inc
23.
Chain pump
–
The chain pump is type of a water pump in which several circular discs are positioned on an endless chain. One part of the chain dips into the water, and the runs through a tube. As the chain is drawn up the tube, water trapped between the discs and is lifted to and discharged at the top. Chain pumps were used for centuries in the ancient Middle East, Europe, China, the earliest evidence for this device is in a Babylonian text from about 700 B. C. They were commonly powered by humans or animals, the device then appeared in ancient Egypt from about 200 B. C. featuring a pair of gear-wheels. A version of the pump was used in Ancient Roman times, sometimes with pots fixed to the chain. Philo of Byzantium wrote of such a device in the 2nd century B. C. the historian Vitruvius mentioned it around 30 B. C, fragments of these buckets were found on the Roman barges of Lake Nemi. Chain pumps were used in European mines during the Renaissance, mineralogist Georg Agricola illustrated them in his De re metallica and they were used in dockyards, and several formed part of the Portsmouth Block Mills complex. Chain pumps were used on naval vessels of the time to pump the bilges. Chain pumps were used in ancient China by at least the 1st century A. D. In China, they were also called dragon backbones, one of the earliest accounts was a description by the Han Dynasty philosopher Wang Chong around A. D.80. Unlike those found in the West, chain pumps in China resembled the square-pallet type instead of the pear-shaped bucket, illustrations of such Chinese chain pumps show them drawing water up a slanted channel. There were also square-pallet chain pumps operated by pedals, from the 1st century onwards, chain pumps were widespread throughout the Chinese countryside. Chinese square-pallet chain pumps were used mostly for irrigation, though they use in public works as well. The infamous Eastern Han court eunuch Zhang Rang once ordered the engineer Bi Lan to construct a series of chain pumps outside the capital city Luoyang. These chain pumps serviced the palaces and living quarters of the Luoyang, ma Jun, the renowned mechanical engineer of the Three Kingdoms era, also constructed a series of chain pumps for watering the palatial gardens of Emperor Ming of Wei. During the period of expansion in Song China, the technology of water-rising devices was improved. For some centuries they had used for moving water for drainage or irrigation purposes
24.
Chainsaw
–
A chainsaw is a portable, mechanical saw which cuts with a set of teeth attached to a rotating chain that runs along a guide bar. It is used in such as tree felling, limbing, bucking, pruning, cutting firebreaks in wildland fire suppression. Chainsaws with specially designed bar and chain combinations have been developed as tools for use in chainsaw art, specialized chainsaws are used for cutting concrete. Chainsaws are sometimes used for cutting ice, for example for ice sculpture, someone who uses a saw is a sawyer. The origin is debated, but a tool was made around 1830 by the German orthopaedist Bernhard Heine. This instrument, the osteotome, had links of a chain carrying small cutting teeth with the set at an angle. As the name implies, this was used to cut bone, the chain hand saw, a fine serrated link chain which cut on the concave side, was invented around 1783-1785. It was illustrated in Aitkens Principles of Midwifery or Puerperal Medicine, Jeffray claimed to have conceived the idea of the chain saw independently about that time but it was 1790 before he was able to have it produced. In 1806, Jeffray published Cases of the Excision of Carious Joints by H. Park, in this communication he translated Moreaus paper of 1803. Park and Moreau described successful excision of diseased joints, particularly the knee, Jeffray explained that the chain saw would allow a smaller wound and protect the adjacent neurovascular bundle. While a heroic concept, symphysiotomy had too many complications for most obstetricians but Jeffrays ideas became accepted, mechanised versions of the chain saw were developed but in the later 19th Century, it was superseded in surgery by the Gigli twisted wire saw. For much of the 19th century, however, the saw was a useful surgical instrument. The earliest patent for an endless chain saw was granted to Samuel J. Bens of San Francisco on January 17,1905. His intent being to fell giant redwoods, the first portable chainsaw was developed and patented in 1918 by Canadian millwright James Shand. After he allowed his rights to lapse in 1930 his invention was developed by what became the German company Festo in 1933. The company now operates as Festool producing portable power tools, in 1927, Emil Lerp, the founder of Dolmar, developed the worlds first gasoline-powered chainsaw and mass-produced them. World War II interrupted the supply of German chain saws to North America, so new manufacturers sprang up including Industrial Engineering Ltd in 1947, Ltd and part of Outboard Marine Corporation, the oldest manufacturer of chainsaws in North America. McCulloch in North America started to produce chainsaws in 1948, the early models were heavy, two-person devices with long bars
25.
Saw chain
–
The saw chain, or cutting chain, is a key component of a chainsaw. It consists of steel held together by rivets, and superficially resembles the bicycle-style roller chain. Its key differences are sharp cutting teeth on the outside of the chain loop, saw chains are used for cutting wood. This may be for harvesting trees for pulp or timber, for tree surgery, whether for hand-held chainsaws, mechanical timber harvesters or chain mortisers, the saw chain has undergone dramatic development since its invention. Modern chains designed for power, high-speed sawing applications will vastly outperform older designs. Saw chains operate by being propelled around a bar, removing material from the kerf by cutting chips from the side. In order to operate properly, the depth to which each tooth cuts must be limited to avoid it binding in the wood. Scratcher chain, like the teeth on a saw, simply uses a multitude of teeth to prevent individual teeth from sinking too far in without undue pressure on the bar. Chipper chain, and all subsequent designs, incorporate a depth gauge on each link to limit depth of cut on each tooth. Individual depth gauges on each tooth also enable the use of skip chain, skip or semi-skip chain has a further reduction in the number of teeth and is used for applications where much debris is produced, such as ripping or cross-cutting very large sections of wood. Skip chain also absorbs less power from the motor per unit length of chain than full-complement chain, very early chainsaws used tooth configurations very similar to conventional hand saws. These were very simple saw teeth following a pattern with no depth gauges as such. They were inefficient and slow in use, and were superseded by chipper chain. They required great skill and a lot of time to sharpen in the leading to extended downtime between sessions. Chipper chain invented by Joseph Cox improved dramatically on the performance of scratcher chain, chipper used a tooth that was curled over the top of the chain, with alternate teeth pointing left and right. Ahead of the tooth was a gauge, which allowed for good clearance around the tooth for chip clearing while limiting the depth of cut. Chipper chains are used for dirty work, since their very large working corner allows the cutter to retain its effective sharpness for a long time in abrasive conditions. Modern chains for use in forestry, tree surgery and firewood cutting come in three basic configurations, the full chisel, the semi-chisel, and the chipper chain
26.
Flat chain
–
Flat chain is a form of chain used chiefly in agricultural machinery. Early machinery made extensive use of flat chain and it has been gradually replaced in most applications by roller chain, which is quieter, lasts longer, and requires less frequent retensioning. Modern flat chain is made from stamped steel, individual links can be put together or taken apart using simple tools, unlike roller chain which requires a master link or special splicing equipment. Today, flat chain is used most often for conveyor belts, because it lends itself well to the attachment of slats, flights, buckets, and prongs used to move material. Such attachments can be welded on in the field, or can be purchased ready-made on a single link, older forms of flat chain were made of iron. Though the sprockets are compatible with modern chain, the two types cannot be spliced together, the Complete Guide to Chain History of Link-Belt Construction Equipment Co. an early manufacturer of flat chain
27.
Timing belt (camshaft)
–
In an interference engine the timing belt or chain is also critical to preventing the piston from striking the valves. A timing belt is usually a toothed belt -- a drive belt with teeth on the inside surface, a timing chain is a roller chain. Most modern production engines use a timing belt or chain to synchronize crankshaft and camshaft rotation. Timing chains were common on production automobiles through the 1970s and 1980s, when timing belts became the norm, but timing chains have seen a resurgence in recent years. Timing chains are more durable than timing belts – though neither is as durable as direct gear drive – however, timing belts are lighter, less expensive. In the internal combustion engine application the timing belt or chain connects the crankshaft to the camshaft, a four-stroke engine requires that the valves open and close once every other revolution of the crankshaft. It has teeth to turn the camshaft synchronised with the crankshaft, in some engine designs the timing belt may also be used to drive other engine components such as the water pump and oil pump. Gear or chain systems are used to connect the crankshaft to the camshaft at the correct timing. However, gears and shafts constrain the relative location of the crankshaft, even where the crankshaft and camshaft are very close together, as in pushrod engines, most engine designers use a short chain drive rather than a direct gear drive. This is because gear drives suffer from frequent torque reversal as the cam profiles kick back against the drive from the crank, leading to excessive noise, fibre or nylon covered gears, with more resilience, are often used instead of steel gears where direct drive is used. Commercial engines and aircraft engines use steel gears only, as a fibre or nylon coated gear can fail suddenly, a belt or chain allows much more flexibility in the relative locations of the crankshaft and camshafts. Also, timing belts do not require lubrication, which is essential with a chain or gears. A timing belt is an application of a synchronous belt used to transmit rotational power synchronously. Timing belts are typically covered by metal or polymer timing belt covers which require removal for inspection or replacement, engine manufacturers recommend replacement at specific intervals. Indicators that the chain may need to be replaced include a rattling noise from the front of the engine. When an automotive timing belt is replaced, care must be taken to ensure that the valve, failure to synchronize correctly can lead to problems with valve timing, and this in turn, in extremes, can cause collision between valves and pistons in interference engines. This is not a unique to timing belts since the same issue exists with all other cam/crank timing methods such as gears or chains. Timing belts must be replaced at the recommended distance and/or time periods
28.
Internal combustion engine
–
An internal combustion engine is a heat engine where the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine, the force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into mechanical energy. The first commercially successful internal combustion engine was created by Étienne Lenoir around 1859, firearms are also a form of internal combustion engine. Working fluids can be air, hot water, pressurized water or even liquid sodium, ICEs are usually powered by energy-dense fuels such as gasoline or diesel, liquids derived from fossil fuels. While there are many applications, most ICEs are used in mobile applications and are the dominant power supply for vehicles such as cars, aircraft. Typically an ICE is fed with fossil fuels like natural gas or petroleum products such as gasoline, there is a growing usage of renewable fuels like biodiesel for compression ignition engines and bioethanol or methanol for spark ignition engines. Hydrogen is sometimes used, and can be made from fossil fuels or renewable energy. Various scientists and engineers contributed to the development of internal combustion engines, in 1791, John Barber developed a turbine. In 1794 Thomas Mead patented a gas engine, also in 1794 Robert Street patented an internal combustion engine, which was also the first to use liquid fuel, and built an engine around that time. In 1798, John Stevens built the first American internal combustion engine, in 1807, Swiss engineer François Isaac de Rivaz built an internal combustion engine ignited by electric spark. In 1823, Samuel Brown patented the first internal combustion engine to be applied industrially, in 1860, Belgian Jean Joseph Etienne Lenoir produced a gas-fired internal combustion engine. In 1864, Nikolaus Otto patented the first atmospheric gas engine, in 1872, American George Brayton invented the first commercial liquid-fuelled internal combustion engine. In 1876, Nikolaus Otto, working with Gottlieb Daimler and Wilhelm Maybach, patented the compressed charge, in 1879, Karl Benz patented a reliable two-stroke gas engine. In 1892, Rudolf Diesel developed the first compressed charge, compression ignition engine, in 1926, Robert Goddard launched the first liquid-fueled rocket. In 1939, the Heinkel He 178 became the worlds first jet aircraft, at one time, the word engine meant any piece of machinery — a sense that persists in expressions such as siege engine. A motor is any machine that produces mechanical power, traditionally, electric motors are not referred to as Engines, however, combustion engines are often referred to as motors. In boating an internal combustion engine that is installed in the hull is referred to as an engine, reciprocating piston engines are by far the most common power source for land and water vehicles, including automobiles, motorcycles, ships and to a lesser extent, locomotives
29.
Ball and chain
–
A ball and chain believed to date to the 17th century was found in the United Kingdom in 2009. It consists of a sphere of high-grade iron approximately 15 centimetres across, the chain is of some 90 centimetres in length and terminates in a leg iron or shackle. The weight of the ball makes it difficult for the person to walk
30.
Physical restraint
–
Physical restraint refers to means of purposely limiting or obstructing the freedom of a persons bodily movement. Usually, binding objects such as handcuffs, legcuffs, ropes, chains and this less commonly also extends to joint locks and pinning techniques. The freedom of movement in terms of locomotion is usually limited, by locking a person into a space, such as a prison cell. This effect can also be achieved by seizing and withholding specific items of clothing, examples can be protective clothing against temperature, hereby factually constraining the individual to remain in a sheltered spot. This also refers to taking away a persons shoes in a situation of captivity, the freedom of movement is practically restricted in many everyday situations without the protection offered by conventional footwear. Various ground textures in urban as well as natural areas can cause substantial physical distress for a shoeless person, ground textures consisting of crushed stone or similar construction aggregate can be practically impossible for a person to walk or run over without wearing shoes. Aside from extreme circumstances, a person is steadily compromised by the usual imponderabilities of most surroundings. Controlling the free movement of detainees by keeping them barefoot is common practice in many countries. A main motive can be seen in the fact, that the effects of frustrating prison escape and curbing acts of resistance are obtained without cost. Further it is an effective complementation of binding restraints, british Police officers are authorised to use leg and arm restraints, if they have been instructed in their use. Pouches carrying restraints are usually carried on the duty belt, for restraint for medical or psychiatric purposes, see medical restraint. Individuals with Disabilities Education Act has stated that Restraints may not be used as an alternative to adequate staff, also, restraint may be used only when aggressive behavior interferes with an individuals own ability to benefit from programming or poses physical threat to others. The misuse of physical restraint has resulted in many deaths, physical restraint can be dangerous, sometimes in unexpected ways. Gagging a restrained person is highly risky, as it involves a risk of asphyxia. Gags that prevent communication may also prevent the communication of distress that might otherwise prevent injury, a survey in the US in 1998 reported an estimated 150 restraint related deaths in care environments. Low frequency fatalities occur with some degree of regularity, an investigated of 45 restraint related deaths in US childcare settings showed 28 of these deaths were reported to have occurred in the prone position. In the UK restraint related deaths would appear to be reported less often, the evidence for effective staff training in the use of medical restraints is at best crude, with evaluation of training programmes being the exception rather than the rule. Vast numbers of staff are trained in ‘physical interventions’ including physical restraint
31.
Boom (navigational barrier)
–
A boom or a chain is an obstacle strung across a navigable stretch of water to control or block navigation. Booms could be military in nature, with the goal of denying access to an enemys ships, booms could also be used, especially along rivers, to force passing vessels to pay a toll. A boom generally floats on the surface, while a chain can be on the surface or below the water, a chain could be made to float with rafts, logs, ships or other wood, making the chain a boom as well. Especially in medieval times, the end of a chain could be attached to a tower or boom tower. This allowed safe raising or lowering of the chain, as they were heavily fortified. By raising or lowering a chain or boom, access could be selectively granted rather than rendering the stretch of water completely inaccessible. The raising and lowering could be accomplished by a mechanism or a capstan. The boom at the siege of Londonderry, for example, was cut by sailors in a longboat, as a key portion of defences, booms were usually heavily defended. This involved shore-based chain towers, batteries or forts, in the Age of Sail, a boom protecting a harbour could have several ships defending it with their broadsides, discouraging assaults on the boom. On some occasions, multiple booms spanned a single stretch of water. ^ Some sources have the chain being dismantled instead of broken by a ship in the Siege of Damietta and in the Raid on the Medway
32.
Chain-link fencing
–
A chain-link fence is a type of woven fence usually made from galvanized or LLDPE-coated steel wire. The wires run vertically and are bent into a zig-zag pattern so that each zig hooks with the wire immediately on one side and this forms the characteristic diamond pattern seen in this type of fence. In the United Kingdom, the firm of Barnard, Bishop & Barnard was established in Norwich to produce chain-link fencing by machine, the process was developed by Charles Barnard in 1844 based on cloth weaving machines. The Anchor Post Fence Co. established in 1891, bought the rights to the machine and was the first company to manufacture chain-link fencing in the United States. Anchor Fence also holds the first United States patent for chain-link, the machine was purchased from a man in 1845 from Belgium who originally invented the wire bending machine. In the United States, fencing usually comes in 20 rod and 50 ft rolls, which can be joined by unscrewing one of the end wires and then screwing it back in so that it hooks both pieces. Common heights include 3 ft,3 ft 6 in,4 ft,5 ft,6 ft,7 ft,8 ft,10 ft, common mesh gauges are 9,11, and 11.5. Mesh length can vary based on need, with the standard mesh length being 2. For tennis courts and ball parks, the most popular height is 10 ft, the popularity of chain-link fence is from its relatively low cost and that the open weave does not obscure sunlight from either side of the fence. One can make a chain-link fence semi-opaque by inserting slats into the mesh, the installation of chain-link fence involves setting posts into the ground and attaching the fence to them. The posts may be steel tubing, timber or concrete and may be driven into the ground or set in concrete. End, corner or gate posts, commonly referred to as terminal posts, posts set between the terminal posts are called line posts and are set at intervals not to exceed 10 feet. The installer attaches the fence at one end, stretches it, finally, the installer ties the fence to the line posts with aluminum wire. Top horizontal rails are used on most chain-link fences, although not necessary, bottom rails may be added in lieu of bottom tension wires, and for taller fences,10 feet or more, intermediate horizontal rails are often added. Once stretched, a bottom wire should be secured to the line posts, one generally installs this wire before installing the chain-link mesh. The manufacturing of chain-link fencing is called weaving, a metal wire, often galvanized to reduce corrosion, is pulled along a rotating long and flat blade, thus creating a somewhat flattened spiral. The spiral continues to rotate past the blade and winds its way through the spiral that is already part of the fence. When the spiral reaches the far end of the fence, the spiral is cut near the blade, next, the spiral is pressed flat and the entire fence is moved up, ready for the next cycle
33.
Mail (armour)
–
Mail is a type of armour consisting of small metal rings linked together in a pattern to form a mesh. A coat of armour is often referred to as a hauberk. The earliest example of surviving mail was found in a chieftains burial located in Ciumești and its invention is commonly credited to the Celts, but there are examples of Etruscan pattern mail dating from at least the 4th century BC. Mail may have inspired by the much earlier scale armour. Mail spread to North Africa, West Africa, the Middle East, Central Asia, India, Tibet, South East Asia, the origins of the word mail are not fully known. One theory is that it derives from the Latin word, macula. Another theory relates the word to the old French, maillier, in modern French, maille refers to a loop or stitch. The Arabic words burnus, برنوس, a burnoose, a cloak, also a chasuble and barnaza, برنز, to bronze. The first attestations of the mail are in Old French and Anglo-Norman, maille, maile, or male or other variants. The modern usage of terms for mail armour is highly contested in popular and, to a lesser degree, since then the word mail has been commonly, if incorrectly, applied to other types of armour, such as in plate-mail. The more correct term is plate armour, civilizations that used mail invented specific terms for each garment made from it. The standard terms for European mail armour derive from French, leggings are called chausses, a hood is a mail coif, a mail collar hanging from a helmet is a camail or aventail. A shirt made from mail is a hauberk if knee-length and a haubergeon if mid-thigh length, a layer of mail sandwiched between layers of fabric is called a jazerant. A waist-length coat in medieval Europe was called a byrnie, although the construction of a byrnie is unclear. Only on artistic and some sources because of the lack of archaeological examples. It was also long, reaching below the hips and covering most of the arms. Other historians claim instead that the Carolingian byrnie was nothing more than a coat of mail, without more certain evidence, this dispute will continue. The use of mail as battlefield armour was common during the Iron Age, the Roman army adopted the technology for their troops in the form of the lorica hamata which was used as a primary form of armour through the Imperial period
34.
Door chain
–
A door chain, security chain, or security door chain consists of a small chain attached to the door frame, which attaches to a track on the door for security purposes. It is a type of lock that is used along with other types of locks to secure a door. Door chains also can be set in place when the door does not need to be opened, door chains installed on hollow-core doors, or that are not anchored into solid materials do not provide protection. This is because the chain can easily be defeated by pushing on a door, the chains are helpful to sound an alert to the person inside that someone is breaking through a door. The noise may be heard by the occupants giving them time to call for help, escape via another exit, door chains are also sometimes used to slow down mentally-challenged individuals who may attempt to exit from inside a structure. Door chains are fairly easy to install and use, use of a door chain provides a little security when dealing with strangers. A properly installed door chain is resistant to tampering from the outside requiring use of force to open the door. Door chains normally come equipped with very short screws which easily rip out, any amount of force capable of defeating a deadbolt will also defeat a door chain. The tracks are straight, and any number of simple tools will allow the chain to be separated from the track. Elderly individuals, uncoordinated people, and individuals with hand tremors may find it difficult to connect the chain to the track, the chain is often a thin metal. Door chains are often installed improperly, making them easily subjected to a number of attacks, uPVC/PVCU front doors are generally unsuitable for retrofit security devices. Security screen doors add a set of hinges or locks to defeat before access to a structure can be granted. If the intention is to keep out, or keep disturbed individuals in. Security screen doors also make it possible to open the main door, as an added benefit, security screen doors can allow the door to be opened, and provide for secure ventilation. The main downside is the cost, which is generally about as much as a regular door, installation can also be difficult, as the doorknobs of the two doors may interfere with each other, and the screen material usually interferes with any peephole devices on the door. A door bar is a device intended to replace door chains. It consists of a U shaped bar that attaches to a hinge on the doorframe, the bar swings over the knob to restrict the full opening of the door. Door bars are easier to use, and can be made of much sturdier material than door chains, also, door bars cannot be defeated in the same way that door chains can be, although they can be defeated just as easily in different ways
35.
Chain gang
–
A chain gang is a group of prisoners chained together to perform menial or physically challenging work as a form of punishment. Such punishment might include repairing buildings, building roads, or clearing land and this system existed primarily in the Southern United States, and by 1955 had been phased out nationwide, with Georgia the last state to abandon the practice. Chain gangs were reintroduced by a few states during the get tough on crime 1990s, the introduction of chain gangs into the United States began shortly after the American Civil War. The southern states needed finances and public works to be performed, Prisoners were a free way for these works to be achieved. A single ankle shackle with a length of chain attached to a heavy ball is known as a ball. It limited prisoner movement and impeded escape, two ankle shackles attached to each other by a short length of chain are known as a hobble or as leg irons. These could be chained to a longer chain with several other prisoners. The walk required to avoid tripping while in leg irons is known as the convict shuffle, a group of prisoners working outside prison walls under close supervision, but without chains, is a work gang. Their distinctive attire and shaven heads served the purpose of displaying their punishment to the public, however, the public was often brutal, swearing at convicts and even throwing things at them. The use of chains could be hazardous, some of the chains used in the Georgia system in the first half of the twentieth century weighed twenty pounds. Some prisoners suffered from shackle sores — ulcers where the ground against their skin. Gangrene and other infections were serious risks, falls could imperil several individuals at once. Modern prisoners are put into handcuffs or wrist manacles and leg irons. This form of restraint is most often used on prisoners expected to be violent, various claims as to the purpose of chain gangs have been offered. These include, punishment societal restitution for the cost of housing, feeding, the use of chain gangs in the United States generally ended in 1955. Chain gangs experienced a resurgence when Alabama began to use again in 1995. Several jurisdictions in the United States have re-introduced prison labor, arizonas modern chain gangs, rather than chipping rocks, digging ditches or other non-productive tasks, often do work of economic benefit to a correctional department, such as removing trash. Opponents claim that the gangs often work outside in oppressive desert heat, a year after reintroducing the chain gang in 1995, Alabama was forced to again abandon the practice pending a lawsuit from, among other organizations, the Southern Poverty Law Center
36.
Legcuffs
–
Legcuffs are physical restraints used on the ankles of a person to allow walking only with a restricted stride and to prevent running and effective physical resistance. Frequently used alternative terms are leg cuffs, shackles, footcuffs, the term fetter shares a root with the word foot. With respect to humans, shackles are typically used on prisoners, Leg shackles also are used for chain gangs to keep them together. Metaphorically, a fetter may be anything that restricts or restrains in any way, the earliest fetters found in archaeological excavations date from the prehistoric age and are mostly of the puzzle lock type. Fetters are also referenced in ancient times in the Bible, roman times already see a variety of restraint types. Some early versions of cup lock shackles can already be found and these were widely used in medieval times but their use declined when mass production made the manufacture of locks built into restraints affordable. Simple fetter types continue to be used like puzzle lock shackles as the typical slave iron or irons riveted shut for prisoners being transported to prison camps. The first built-in locks often were of a simple screw-type but soon developed into the Darby type, in comparison to handcuffs the wearing of leg irons may be found less restrictive. Thus the prison authorities in several countries deem their long-term use acceptable, in order to avoid condoning this disputed practice, the countries of the European Union have banned exporting leg irons into non-EU countries. The countries that continue to make prisoners wear fetters long term now tend to resort to manufacturing their own restraints, ankle monitor Bilboes Handcuffs Hobble Leg Thumbcuffs
37.
Handcuffs
–
Handcuffs are restraint devices designed to secure an individuals wrists close together. They comprise two parts, linked together by a chain, a hinge, or rigid bar, each half has a rotating arm which engages with a ratchet that prevents it from being opened once closed around a persons wrist. Without the key, the handcuffs cannot be removed and so the person is unable to move his or her wrists more than a few centimetres/inches apart. This is usually done to prevent suspected criminals from escaping police custody, there are three main types of contemporary metal handcuffs, chain, hinged, and rigid solid bar handcuffs. While bulkier to carry, rigid handcuffs permit several variations in cuffing, hiatts Speedcuffs are rigid handcuffs used by most police forces in the United Kingdom. Both rigid and hinged cuffs can be used one-handed to apply pain-compliance/control techniques that are not workable with the type of cuff. Various accessories are available to improve the security or increase the rigidity of handcuffs, including boxes that fit over the chain or hinge and can themselves be locked with a padlock. In 1933 the Royal Canadian Mounted Police used a type called Mitten Handcuffs to prevent criminals from being able to grab an object like the officers gun, while used by some in law enforcement it was never popular. Handcuffs may be manufactured from metals, including carbon steel, stainless steel and aluminium. Oversized handcuffs are available from a number of manufacturers, the National Museum of Australia has a number of handcuffs in its collection dating from the late 19th and early 20th centuries. These includeT-type Come Along, D-type and Figure-8 handcuffs and they can be carried in large quantities by soldiers and police and are therefore well-suited for situations where many may be needed, such as during large-scale protests and riots. In recent years, airlines have begun to carry plastic handcuffs as a way to restrain disruptive passengers. Disposable restraints could be considered to be cost-inefficient, they cannot be loosened and it is not unheard of for a single subject to receive five or more sets of disposable restraints in his or her first few hours in custody. However, aforementioned usage means that cheap handcuffs are available in situations where steel ones would normally lie unused for long times, in addition, plastic restraints are believed by many to be more likely to inflict nerve or soft-tissue damage to the wearer than metal handcuffs. Legcuffs are similar to handcuffs, but have a larger inner perimeter so that they fit around a persons ankles, some models consist of elliptically contoured cuffs so that they widely adapt to the anatomy of the ankle, minimizing pressure on the Achillestendon. Standard-type leg irons have a chain connecting the two cuffs compared to handcuffs. Legcuffs are also used when transporting prisoners outside of an area to prevent attempts to escape. When being placed in standard legcuffs, the prisoner will still have the possibility to manage normal steps and can walk independently
38.
Chain boat navigation
–
Chain-boat navigation or chain-ship navigation is a little-known chapter in the history of shipping on European rivers. From around the middle of the 19th century, vessels called chain boats were used to haul strings of barges upstream by using a fixed chain lying on the bed of a river. The chain was raised from the riverbed to pass over the deck of the steamer, being hauled by a heavy winch powered by a steam engine. A variety of companies operated chain boat services on such as the Elbe, Rhine, Neckar, Main, Saale, Havel, Spree and Saône as well as other rivers in Belgium. Chain boats were used in the United States. The practice fell out of favour in the early 20th century when steamships with powerful engines, the transportation of goods by river in the early days of the chain boat was restricted to wooden ships without their own on-board power. When travelling downstream, boats were either simply propelled along by the current or sails would employ wind power, to move upriver, men or draught animals on towpaths were used to haul the boats on long ropes. In shallow waters boats could also be propelled upstream by long poles, where towing from a towpath on the riverbank was not possible, a method known as warping was used. These sections of river could be negotiated by anchoring a rope ahead of the boat, in an illuminated manuscript dating to 1438, the Italian engineer, Jacopo Mariano, illustrated the fundamental concept on which chain boat navigation was subsequently based. The boat is pulling itself upstream on a cable laid along the river, the rope is wrapped around a central shaft driven by two, side-mounted water wheels. Behind the river craft is a small object being pulled by the current. In 1595 Fausto Veranzio described a system of cable boat navigation that enabled greater speeds, two boats are connected by a cable that is led round a pulley anchored firmly to the riverbed. The smaller boat, which is travelling downstream, is moving very fast, the large barge in the picture has two, side-mounted water wheels that coil up the cable and increase its speed further. It is not, however, recorded whether the system was used in practice, at that time,50 men were needed to negotiate this section of the river. According to Marperger, with the use of levers it should have been possible for five or six men to successfully effect the passage of the boat. At the same time, however, he stressed that the machine was produced, from his description, elements of this basic principle seem to be similar to those subsequently used later in building chain boats. This section of river was later to become the point for the first chain boats in Germany. The first practical attempts to use a boat were in 1732 at the instigation of Marshal Maurice of Saxony
39.
Lewis (lifting appliance)
–
A lewis is one of a category of lifting devices used by stonemasons to lift large stones into place with a crane, chain block, or winch. It is inserted into a prepared hole, or seating, in the top of a stone. The specially shaped hole that is shaped to fit the device is known as a lewis hole, lewis holes in the uppermost masonry coursings are neatly repaired with matching indented plugs after the stone has been set in place. A lewis is most useful when it is not possible to lift the stone with chains or slings, because of either the location or shape of the stone, or delicate projections. Examples include the stone in a string course, cylindrical column drums, decorated column capitals. Heavy ashlar stones are also bedded using a lewis, for this reason, a safety sling should always be used together with the lewis until the stone is reasonably close to its final position. Lifting the stone a small distance from the ground before hoisting is the best way to test a lewis, any sign of looseness or damage should be corrected by adjusting the lewis hole or packing the lewis with metal shims. Bedding a stone using a lewis, The stone is placed on dunnage laid flat with enough clearance for a bed to be placed beneath it. The safety straps are removed, the stone is lifted using the lewis alone, the stone is then lowered onto the mortar bed, and positioned with sharp taps from a rubber mallet. There are a number of different types of lewis used in the stonemasonry trade, the legs fit into a seating cut in the top of the stone, above the centre of mass. When the top of the legs are pulled together by the rings. The split-pin lewis is similar to the chain-linked lewis in that it uses an action to produce friction against the inside of the lewis hole. The two legs, semicircular in section, lie side-by-side, and fit inside a 32 mm diameter hole drilled to a depth of 82 mm. This type of seating is the simplest to prepare, requiring a single drilled hole. A two-pinned lewis consists of two 13 mm diameter steel pins, linked by a short chain, the pins are inserted into opposing holes that are drilled into the top of the stone at about 15° from vertical, and at least 75 mm deep. It operates by gripping the stone as the weight of the stone is taken up by a crane or winch, the advantage of using this type of lewis is that it is simple to prepare—two angled drill holes are all that is necessary. Like other types of lewis, it is susceptible to pulling out as the stone is lifted and it should always be tested before hoisting, and used in conjunction with safety slings. A three-legged lewis, also known as a lewis, St Peters keys
40.
Curb chain
–
A curb chain, or curb strap, is a piece of horse tack required for proper use on any type of curb bit. It is a linked chain or flat strap that runs under the chin groove of the horse. It has a buckle or hook attachment and English designs have a fly link in the middle to hold a lip strap, on English bridles the horse is bridled with the curb chain undone on one side, then connected once on the horse. On western bridles, the chain is kept buckled to both sides of the bit. The main use of the chain is to enhance and control the lever action of a curb bit. Additionally, it helps to keep the bit steady and in place within the mouth, the curb chain applies pressure to the curb groove under a horses chin when the curb rein of the bit is used. When the curb rein is pulled, the shank of the bit rotates back towards the chest of the horse and the cheek of the bit rotates forward. The curb chain is attached to the rings at the end of the cheek, so, as the cheek moves forward, the tightness of the curb chain has a great effect on the action of the bit. If the bit is used without a chain, it loses its leverage action. If used with a curb chain, it allows the shanks to rotate more before the curb chain is tight enough to act as a fulcrum. This extra rotation can warn the horse before pressure is exerted on his mouth, additionally, it can completely nullify the correct action of the curb, making its use pointless. There are two undesirable consequences when using a tight curb chain. First, the bit immediately exerts curb pressure and increased pressure on the bars as soon as pressure is applied to the reins, secondly, an extremely tight curb chain causes the mouthpiece to constantly push down on the sensitive tongue, never allowing the horse relief. A curb chain is adjusted so it comes into action when the shank rotates 45 degrees back. However, skilled riders with experience with the curb bit may adjust the chain tighter to accommodate the needs of the horse, type of equipment. However, keeping the curb chain looser allows more accommodation for rider error, the curb chain should be applied by twisting it clockwise on one hook until it is flat, and then attaching it to the other hook. A twisted curb chain is far harsher in its effect than a flat one, curb chains vary in width and linkage. Thinner curb chains are more severe, ones that are too thin are banned in competition, for horses that are sensitive or that are rubbed by the chain, a cover made of rubber, neoprene, leather, or gel can be used, or a leather curb strap
41.
High-tensile chain
–
A high-tensile chain, also referred to as a transport chain, is a link chain with a high tensile strength used for drawing or securing loads. This type of chain usually consist of metal, oblong torus-shaped links for high strength. When the ability to grasp the load is required, a hook is used. In summary, transport chains are high strength chains used in applications where much strength is needed yet the task served is rather straightforward. Hoist Lifting hook Shackle Clevis fastener
42.
Jack chain
–
A jack chain is a type of chain made of thin wire, with figure-eight-shaped links, and loops at right angles to each other. Jack chains are used to suspend fixtures such as lights or signs, for decorative purposes. Jack chain may be manufactured as either single-jack chain or as double-jack chain, if double-jack, the lower loop is formed of two strands of wire rather than just one as in a single-jack. Before the days of lavatory cisterns being close to the pan, a jack chain is a tool attached to a toothed chain for moving logs. A jack chain is a form of arm protection for the 15th century infantry soldier who typically was not dressed in plate armor, image of various sizes of jack chain
"Chain". Encyclopædia Britannica. 5 (11th ed.). 1911.
"