A connecting rod is a rigid member which connects a piston to a crank or crankshaft in a reciprocating engine. Together with the crank, it forms a simple mechanism that converts reciprocating motion into rotating motion. A connecting rod may convert rotating motion into reciprocating motion, its original use. Earlier mechanisms, such as the chain, could only impart pulling motion. Being rigid, a connecting rod may transmit either push or pull, allowing the rod to rotate the crank through both halves of a revolution. In a few two-stroke engines the connecting rod is only required to push. Today, the connecting rod is best known through its use in internal combustion piston engines, such as automobile engines; these are of a distinctly different design from earlier forms of connecting rod used in steam engines and steam locomotives. Evidence for the connecting rod appears in the late 3rd century Hierapolis sawmill in Roman Asia, it appears in two 6th century Byzantine-era saw mills excavated at Ephesus, Asia Minor and Gerasa, Roman Syria.
The crank and connecting rod mechanism of these Roman-era watermills converted the rotary motion of the waterwheel into the linear movement of the saw blades. Sometime between 1174 and 1206 in the Artuqid State, the Arab inventor and engineer Al-Jazari described a machine which incorporated the connecting rod with a crankshaft to pump water as part of a water-raising machine, though the device was complex. In Renaissance Italy, the earliest evidence of a − albeit mechanically misunderstood − compound crank and connecting-rod is found in the sketch books of Taccola. A sound understanding of the motion involved is displayed by the painter Pisanello who showed a piston-pump driven by a water-wheel and operated by two simple cranks and two connecting-rods. By the 16th century, evidence of cranks and connecting rods in the technological treatises and artwork of Renaissance Europe becomes abundant; the first steam engine, Newcomen's atmospheric engine, was single-acting: its piston only did work in one direction and so these used a chain rather than a connecting rod.
Their output rocked forth, rather than rotating continuously. Steam engines after this are double-acting: their internal pressure works on each side of the piston in turn; this requires a seal around the piston rod and so the hinge between the piston and connecting rod is placed outside the cylinder, in a large sliding bearing block called a crosshead. In a steam locomotive, the crank pins are mounted directly on one or more pairs of driving wheels, the axle of these wheels serves as the crankshaft; the connecting rods, run between the crank pins and crossheads, where they connect to the piston rods. Crossheads or trunk guides are used on large diesel engines manufactured for marine service; the connecting rods of smaller steam locomotives are of rectangular cross-section but, on small locomotives, marine-type rods of circular cross-section have been used. Stephen Lewin, who built both locomotive and marine engines, was a frequent user of round rods. Gresley's A4 Pacifics, such as Mallard, had an alloy steel connecting rod in the form of an I-beam with a web, only 0.375 in thick.
On Western Rivers steamboats, the connecting rods are properly called pitmans, are sometimes incorrectly referred to as pitman arms. In modern automotive internal combustion engines, the connecting rods are most made of steel for production engines, but can be made of T6-2024 and T651-7075 aluminum alloys or titanium for high-performance engines, or of cast iron for applications such as motor scooters, they are not rigidly fixed at either end, so that the angle between the connecting rod and the piston can change as the rod moves up and down and rotates around the crankshaft. Connecting rods in racing engines, may be called "billet" rods, if they are machined out of a solid billet of metal, rather than being cast or forged; the small end attaches to the piston pin, gudgeon pin or wrist pin, most press fit into the connecting rod but can swivel in the piston, a "floating wrist pin" design. The big end connects to the crankpin on the crank throw, in most engines running on replaceable bearing shells accessible via the connecting rod bolts which hold the bearing "cap" onto the big end.
There is a pinhole bored through the bearing on the big end of the connecting rod so that pressurized lubricating motor oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings. Most small two-stroke engines and some single cylinder four-stroke engines avoid the need for a pumped lubrication system by using a rolling-element bearing instead, however this requires the crankshaft to be pressed apart and back together in order to replace a connecting rod. A major source of engine wear is the sideways force exerted on the piston through the connecting rod by the crankshaft, which wears the cylinder into an oval cross-section rather than circular, making it impossible for piston rings to seal against the cylinder walls. Geometrically, it can be seen that longer connecting rods will reduce the amount of this sideways force, therefore lead to longer engine life
Overhead camshaft abbreviated to OHC, is a valvetrain configuration which places the camshaft of an internal combustion engine of the reciprocating type within the cylinder heads and drives the valves or lifters in a more direct manner compared with overhead valves and pushrods. Compared with OHV pushrod systems with the same number of valves, the reciprocating components of the OHC system are fewer and have a lower overall mass. Though the system that drives the camshafts may be more complex, most engine manufacturers accept that added complexity as a trade-off for better engine performance and greater design flexibility; the fundamental reason for the OHC valvetrain is that it offers an increase in the engine's ability to exchange induction and exhaust gases. Another performance advantage is gained as a result of the better optimised port configurations made possible with overhead camshaft designs. With no intrusive pushrods, the overhead camshaft cylinder head design can use straighter ports of more advantageous cross-section and length.
The OHC design allows for higher engine speeds than comparable cam-in-block designs, as a result of having lower valvetrain mass. The higher engine speeds thus allowed increases power output for a given torque output. Disadvantages of the OHC design include the complexity of the camshaft drive, the need to re-time the drive system each time the cylinder head is removed, the accessibility of tappet adjustment if necessary. In earlier OHC systems, including inter-war Morrises and Wolseleys, oil leaks in the lubrication systems were an issue. Single overhead camshaft is a design. In an inline engine, this means there is one camshaft in the head, whilst in an engine with more than one cylinder head, such as a V engine or a horizontally-opposed engine – there are two camshafts, one per cylinder bank. In the SOHC design, the camshaft operates the valves traditionally via a bucket tappet. SOHC cylinder heads are less expensive to manufacture than double overhead camshaft cylinder heads. Timing belt replacement can be easier since there are fewer camshaft drive sprockets that need to be aligned during the replacement procedure.
SOHC designs offer reduced complexity compared with overhead valve designs when used for multivalve cylinder heads, in which each cylinder has more than two valves. An example of an SOHC design using shim and bucket valve adjustment was the engine installed in the Hillman Imp, a small, early-1960s two-door saloon car with a rear-mounted aluminium-alloy engine based on the Coventry Climax FWMA race engines. Exhaust and inlet manifolds were both on the same side of the engine block; this did, offer excellent access to the spark plugs. In the early 1980s, Toyota and Volkswagen Group used a directly actuated SOHC parallel valve configuration with two valves for each cylinder; the Toyota system used hydraulic tappets. The Volkswagen system used bucket tappets with shims for valve-clearance adjustment; the multivalve Sprint version of the Triumph Slant-4 engine used a system where the camshaft was placed directly over the inlet valves, with the same cams that opened the intake valves directly opening the exhaust valves via rocker arms.
Honda used a similar valvetrain system in their motorcycles, using the term "Unicam" for the concept. This system uses one camshaft for each bank of cylinder heads, with the cams operating directly onto the inlet valve, indirectly, through a short rocker arm, on the exhaust valve; this allows a light valvetrain to operate valves in a flat combustion chamber. The Unicam valve train was first used in single cylinder dirt bikes and has been used on the Honda VFR1200 since 2010. A dual overhead camshaft valvetrain layout is characterised by two camshafts located within the cylinder head, one operating the intake valves and the other one operating the exhaust valves; this design reduces valvetrain inertia more than is the case with an SOHC engine, since the rocker arms are reduced in size or eliminated. A DOHC design exhaust valves than in SOHC engines; this can give a less restricted airflow at higher engine speeds. DOHC with a multivalve design allows for the optimum placement of the spark plug, which in turn improves combustion efficiency.
Engines having more than one bank of cylinders with two camshafts in total remain SOHC and "twin cam" unless each cylinder bank has two camshafts. Although the term "twin cam" is used to refer to DOHC engines, it is imprecise, as it includes designs with two block-mounted camshafts. Examples include the Harley-Davidson Twin Cam engine, Riley car engines from 1926 to the mid 1950s, Triumph motorcycle parallel-twins from the 1930s to the 1980s, Indian Chief and Scout V-twins from 1920 to the 1950s; the terms "multivalve" and "DOHC" do not refer to the same thing: not all multivalve engines are DOHC and not all DOHC engines are multivalve. Examples of DOHC engines with two valves per cylinder include the Alfa Romeo Twin Cam engine, the Jaguar XK6 engine and the Lotus Ford Twin Cam engine. Most recent DOHC engines are multivalve, with between five valves per cylinder. More than two overhead camshafts are not known to have been tried in a production engine. However, MotoCzysz has designed a motorcycle engine with a triple overhead camshaft configuration, with the intake ports descending through the cylind
A car is a wheeled motor vehicle used for transportation. Most definitions of car say they run on roads, seat one to eight people, have four tires, transport people rather than goods. Cars came into global use during the 20th century, developed economies depend on them; the year 1886 is regarded as the birth year of the modern car when German inventor Karl Benz patented his Benz Patent-Motorwagen. Cars became available in the early 20th century. One of the first cars accessible to the masses was the 1908 Model T, an American car manufactured by the Ford Motor Company. Cars were adopted in the US, where they replaced animal-drawn carriages and carts, but took much longer to be accepted in Western Europe and other parts of the world. Cars have controls for driving, passenger comfort, safety, controlling a variety of lights. Over the decades, additional features and controls have been added to vehicles, making them progressively more complex; these include rear reversing cameras, air conditioning, navigation systems, in-car entertainment.
Most cars in use in the 2010s are propelled by an internal combustion engine, fueled by the combustion of fossil fuels. Electric cars, which were invented early in the history of the car, began to become commercially available in 2008. There are benefits to car use; the costs include acquiring the vehicle, interest payments and maintenance, depreciation, driving time, parking fees and insurance. The costs to society include maintaining roads, land use, road congestion, air pollution, public health, health care, disposing of the vehicle at the end of its life. Road traffic accidents are the largest cause of injury-related deaths worldwide; the benefits include on-demand transportation, mobility and convenience. The societal benefits include economic benefits, such as job and wealth creation from the automotive industry, transportation provision, societal well-being from leisure and travel opportunities, revenue generation from the taxes. People's ability to move flexibly from place to place has far-reaching implications for the nature of societies.
There are around 1 billion cars in use worldwide. The numbers are increasing especially in China and other newly industrialized countries; the word car is believed to originate from the Latin word carrus or carrum, or the Middle English word carre. In turn, these originated from the Gaulish word karros, it referred to any wheeled horse-drawn vehicle, such as a cart, carriage, or wagon. "Motor car" is attested from 1895, is the usual formal name for cars in British English. "Autocar" is a variant, attested from 1895, but, now considered archaic. It means "self-propelled car"; the term "horseless carriage" was used by some to refer to the first cars at the time that they were being built, is attested from 1895. The word "automobile" is a classical compound derived from the Ancient Greek word autós, meaning "self", the Latin word mobilis, meaning "movable", it entered the English language from French, was first adopted by the Automobile Club of Great Britain in 1897. Over time, the word "automobile" fell out of favour in Britain, was replaced by "motor car".
"Automobile" remains chiefly North American as a formal or commercial term. An abbreviated form, "auto", was a common way to refer to cars in English, but is now considered old-fashioned; the word is still common as an adjective in American English in compound formations like "auto industry" and "auto mechanic". In Dutch and German, two languages related to English, the abbreviated form "auto" / "Auto", as well as the formal full version "automobiel" / "Automobil" are still used — in either the short form is the most regular word for "car"; the first working steam-powered vehicle was designed — and quite built — by Ferdinand Verbiest, a Flemish member of a Jesuit mission in China around 1672. It was a 65-cm-long scale-model toy for the Chinese Emperor, unable to carry a driver or a passenger, it is not known with certainty if Verbiest's model was built or run. Nicolas-Joseph Cugnot is credited with building the first full-scale, self-propelled mechanical vehicle or car in about 1769, he constructed two steam tractors for the French Army, one of, preserved in the French National Conservatory of Arts and Crafts.
His inventions were, handicapped by problems with water supply and maintaining steam pressure. In 1801, Richard Trevithick built and demonstrated his Puffing Devil road locomotive, believed by many to be the first demonstration of a steam-powered road vehicle, it was unable to maintain sufficient steam pressure for long periods and was of little practical use. The development of external combustion engines is detailed as part of the history of the car but treated separately from the development of true cars. A variety of steam-powered road vehicles were used during the first part of the 19th century, including steam cars, steam buses and steam rollers. Sentiment against them led to the Locomotive Acts of 1865. In 1807, Nicéphore Niépce and his brother Claude created what was the world's first internal combustion engine, but they chose to install it in a boat on the river Saone in France. Coincidentally, in 1807 the Swiss inventor François Isaac de Rivaz designed his own'de Rivaz internal combustion engine' and used it to develop the world's first vehicle to be powered by such an engine.
A bearing is a machine element that constrains relative motion to only the desired motion, reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads applied to the parts. Rotary bearings hold rotating components such as shafts or axles within mechanical systems, transfer axial and radial loads from the source of the load to the structure supporting it; the simplest form of bearing, the plain bearing, consists of a shaft rotating in a hole. Lubrication is used to reduce friction. In the ball bearing and roller bearing, to prevent sliding friction, rolling elements such as rollers or balls with a circular cross-section are located between the races or journals of the bearing assembly. A wide variety of bearing designs exists to allow the demands of the application to be met for maximum efficiency, reliability and performance.
The term "bearing" is derived from the verb "to bear". The simplest bearings are bearing surfaces, cut or formed into a part, with varying degrees of control over the form, size and location of the surface. Other bearings are separate devices installed into a machine part; the most sophisticated bearings for the most demanding applications are precise devices. The invention of the rolling bearing, in the form of wooden rollers supporting, or bearing, an object being moved is of great antiquity, may predate the invention of the wheel. Though it is claimed that the Egyptians used roller bearings in the form of tree trunks under sleds, this is modern speculation, they are depicted in their own drawings in the tomb of Djehutihotep as moving massive stone blocks on sledges with liquid-lubricated runners which would constitute a plain bearing. There are Egyptian drawings of bearings used with hand drills; the earliest recovered example of a rolling element bearing is a wooden ball bearing supporting a rotating table from the remains of the Roman Nemi ships in Lake Nemi, Italy.
The wrecks were dated to 40 BC. Leonardo da Vinci incorporated drawings of ball bearings in his design for a helicopter around the year 1500; this is the first recorded use of bearings in an aerospace design. However, Agostino Ramelli is the first to have published sketches of thrust bearings. An issue with ball and roller bearings is that the balls or rollers rub against each other causing additional friction which can be reduced by enclosing the balls or rollers within a cage; the captured, or caged, ball bearing was described by Galileo in the 17th century. The first practical caged-roller bearing was invented in the mid-1740s by horologist John Harrison for his H3 marine timekeeper; this uses the bearing for a limited oscillating motion but Harrison used a similar bearing in a rotary application in a contemporaneous regulator clock. The first modern recorded patent on ball bearings was awarded to Philip Vaughan, a British inventor and ironmaster who created the first design for a ball bearing in Carmarthen in 1794.
His was the first modern ball-bearing design, with the ball running along a groove in the axle assembly. Bearings have played a pivotal role in the nascent Industrial Revolution, allowing the new industrial machinery to operate efficiently. For example, they saw use for holding wheel and axle to reduce friction over that of dragging an object by making the friction act over a shorter distance as the wheel turned; the first plain and rolling-element bearings were wood followed by bronze. Over their history bearings have been made of many materials including ceramic, glass, bronze, other metals and plastic which are all used today. Watch makers produce "jeweled" watches using sapphire plain bearings to reduce friction thus allowing more precise time keeping. Basic materials can have good durability; as examples, wooden bearings can still be seen today in old clocks or in water mills where the water provides cooling and lubrication. The first patent for a radial style ball bearing was awarded to Jules Suriray, a Parisian bicycle mechanic, on 3 August 1869.
The bearings were fitted to the winning bicycle ridden by James Moore in the world's first bicycle road race, Paris-Rouen, in November 1869. In 1883, Friedrich Fischer, founder of FAG, developed an approach for milling and grinding balls of equal size and exact roundness by means of a suitable production machine and formed the foundation for creation of an independent bearing industry; the modern, self-aligning design of ball bearing is attributed to Sven Wingquist of the SKF ball-bearing manufacturer in 1907, when he was awarded Swedish patent No. 25406 on its design. Henry Timken, a 19th-century visionary and innovator in carriage manufacturing, patented the tapered roller bearing in 1898; the following year he formed a company to produce his innovation. Over a century the company grew to make bearings of all types, including specialty steel and an array of related products and services. Erich Franke invented and patented the wire race bearing in 1934, his focus was on a bearing design with a cross section as small as possible and which could be integrated into the enclosing design.
After World War II he founded together with Gerh
A block heater warms an engine to increase the chances that the engine will start as well as warm up the vehicle faster than it would in cold weather. The most common type is an electric heating element in the cylinder block, connected through a power cord routed through the vehicle's grille; the block heater may replace one of the engine's core plugs. In this fashion, the heater element is immersed in the engine's coolant, which keeps most of the engine warm; this type of heater does not come with a pump. They may be installed in line with one of the radiator or heater hoses; some heaters pump and circulate the engine coolant while heating, others only heat the still coolant in the reservoir. Block heaters that run directly on the vehicle's own gasoline or diesel fuel supply are available; the coolant is heated and circulated by thermosiphon, through the engine and the vehicle's heater core. Heaters are available for engine oil so that warm oil can circulate throughout the engine during start up.
The easier starting results from warmer, less viscous engine oil and less condensation of fuel on cold metal surfaces inside the engine. Block heaters or coolant heaters are found on permanently installed systems using diesel engines to allow standby generator sets to take up load in an emergency. Block heaters are used in regions with cold winters such as the northern United States, Canada and Scandinavia. In colder climates, block heaters are standard equipment in new vehicles. In cold climates, electrical outlets are sometimes found in public or private parking lots in multi-storey car parks; some parking lots cycle the power on for 20 minutes and off for 20 minutes, to reduce electricity costs. Research by the Agricultural Engineering Department of the University of Saskatchewan has shown that operating a block heater for longer than four hours prior to starting a vehicle is a waste of energy, it was found that coolant temperature increased by 20 °C degrees in that period, regardless of the initial temperature.
Four tests were run at ambient temperatures ranging from −11 to −29 °C or 12 to −20 °F. Engine oil temperature was found to increase over these periods by just 5 °C. There are alternatives to a block heater; these include heaters attached to the engine's oil pan with magnets. Dipstick heaters can be installed in place of the engine's oil dipstick. Heated blankets are available for the entire engine area, as well. A timer can be used with any of these heaters; this can help lower the electrical costs of using a block heater. Some cars, such as the second generation Toyota Prius, pump hot coolant from the cooling system into a 3-litre insulated thermos-style reservoir at shutdown, where it stays warm for up to 3 days. Andrew Freeman of Grand Forks, North Dakota, invented the head bolt heater around 1940 and received a patent for it on November 8, 1949. In 1951, Freeman received another patent on an improved head bolt heater; these early heaters replaced one of the engine's cylinder head bolts with a hollow, threaded shank containing a resistive heating element.
Before the block heater was introduced, people used a variety of methods to warm engines before starting them, such as pouring hot water on the engine block or draining the engine's oil for storage inside overnight. Some shoveled embers underneath their vehicle's engine to obtain the same effect. During the dawn of aviation in pre-war Northern Canada, aviators flew with flight engineers who were responsible for preparing the radial engines for shutdown and startup to reduce the effects of subzero temperatures; the flight engineer was responsible for draining the oil into buckets at night, preheating the engine and buckets of oil using a blanket wrapped around the engine and a device known as a blow pot – a kerosene jet-heater used for several hours prior to flight. During the first Russian winter on the Eastern Front in the Second World War, the Luftwaffe could not stop the oil freezing in the engines of their Messerschmitts because of the extreme cold. A captured Soviet airman showed them how pouring aviation fuel into the aircraft's oil sump would thaw the oil.
Another solution learned from the Soviets, was to ignite fuel in the space around the engine
An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines, like the internal combustion engine, burn a fuel to create heat, used to do work. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air, clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and motion; the word engine derives from Old French engin, from the Latin ingenium–the root of the word ingenious. Pre-industrial weapons of war, such as catapults and battering rams, were called siege engines, knowledge of how to construct them was treated as a military secret; the word gin, as in cotton gin, is short for engine. Most mechanical devices invented during the industrial revolution were described as engines—the steam engine being a notable example. However, the original steam engines, such as those by Thomas Savery, were not mechanical engines but pumps.
In this manner, a fire engine in its original form was a water pump, with the engine being transported to the fire by horses. In modern usage, the term engine describes devices, like steam engines and internal combustion engines, that burn or otherwise consume fuel to perform mechanical work by exerting a torque or linear force. Devices converting heat energy into motion are referred to as engines. Examples of engines which exert a torque include the familiar automobile gasoline and diesel engines, as well as turboshafts. Examples of engines which produce thrust include rockets; when the internal combustion engine was invented, the term motor was used to distinguish it from the steam engine—which was in wide use at the time, powering locomotives and other vehicles such as steam rollers. The term motor derives from the Latin verb moto which means to maintain motion, thus a motor is a device. Motor and engine are interchangeable in standard English. In some engineering jargons, the two words have different meanings, in which engine is a device that burns or otherwise consumes fuel, changing its chemical composition, a motor is a device driven by electricity, air, or hydraulic pressure, which does not change the chemical composition of its energy source.
However, rocketry uses the term rocket motor though they consume fuel. A heat engine may serve as a prime mover—a component that transforms the flow or changes in pressure of a fluid into mechanical energy. An automobile powered by an internal combustion engine may make use of various motors and pumps, but all such devices derive their power from the engine. Another way of looking at it is that a motor receives power from an external source, converts it into mechanical energy, while an engine creates power from pressure. Simple machines, such as the club and oar, are prehistoric. More complex engines using human power, animal power, water power, wind power and steam power date back to antiquity. Human power was focused by the use of simple engines, such as the capstan, windlass or treadmill, with ropes and block and tackle arrangements; these were used in cranes and aboard ships in Ancient Greece, as well as in mines, water pumps and siege engines in Ancient Rome. The writers of those times, including Vitruvius and Pliny the Elder, treat these engines as commonplace, so their invention may be more ancient.
By the 1st century AD, cattle and horses were used in mills, driving machines similar to those powered by humans in earlier times. According to Strabo, a water powered mill was built in Kaberia of the kingdom of Mithridates during the 1st century BC. Use of water wheels in mills spread throughout the Roman Empire over the next few centuries; some were quite complex, with aqueducts and sluices to maintain and channel the water, along with systems of gears, or toothed-wheels made of wood and metal to regulate the speed of rotation. More sophisticated small devices, such as the Antikythera Mechanism used complex trains of gears and dials to act as calendars or predict astronomical events. In a poem by Ausonius in the 4th century AD, he mentions a stone-cutting saw powered by water. Hero of Alexandria is credited with many such wind and steam powered machines in the 1st century AD, including the Aeolipile and the vending machine these machines were associated with worship, such as animated altars and automated temple doors.
Medieval Muslim engineers employed gears in mills and water-raising machines, used dams as a source of water power to provide additional power to watermills and water-raising machines. In the medieval Islamic world, such advances made it possible to mechanize many industrial tasks carried out by manual labour. In 1206, al-Jazari employed a crank-conrod system for two of his water-raising machines. A rudimentary steam turbine device was described by Taqi al-Din in 1551 and by Giovanni Branca in 1629. In the 13th century, the solid rocket motor was invented in China. Driven by gunpowder, this simplest form of internal combustion engine was unable to deliver sustained power, but was useful for propelling weaponry at high speeds towards enemies in battle and for fireworks. After invention, this innovation spread throughout Europe; the Watt steam engine was the first type of steam engine to make use of steam at a pressure just above atmospheric to drive the piston he