Ian Allan Publishing
Ian Allan Publishing is a UK publisher, established in 1942, which specialised in transport books. It was founded by Ian Allan. In 1942 Ian Allan working in the public relations department for Southern Railway at Waterloo station, decided he could deal with many of the requests he received about rolling stock by collecting the information into a book; the result was his first book, "ABC of Southern Locomotives". This proved to be a success, contributing to the emergence of trainspotting as a popular hobby in the UK, leading to the formation of the company; the company has grown from a small producer of books for train enthusiasts and spotters to a large transport publisher. Each year it publishes books covering subjects such as military and civil aviation and maritime topics, trams and steam railways, including history and modern operations; the headquarters is at the western end of Shepperton railway station in Surrey. At the end of 2016, the company announced. Crécy Publishing acquired these titles, including the Oxford and abc imprints, but would no longer publish these under the Ian Allan name.
Ian Allan Publishing has acquired several imprints. The Locomotive Publishing Company in 1956 Oxford Publishing Company was purchased in 1998 from Haynes Publishing Group and has become a prominent and well-regarded railway list. Midland Publishing was acquired in 1999; the Midland imprint provides a range of specialist illustrated titles, covering military aviation subjects from World War II to the present day. In civil aviation, comprehensive works of reference are published frequently. Classic Publications, a publisher of aviation titles, was added in 2002, bringing another imprint considered important in the World War II aviation market. Ian Allan Publishing's trade representation is provided by Amalgamated Book Services for its own imprints and a growing list of associated publishers. Midland Counties Publications, acquired by Ian Allan Publishing at the same time as Midland Publishing, was established in the 1970s with the objective of selling books at aviation events and by mail order to a growing number of enthusiasts who could not always find the publications they wanted to read on the shelves of their local High Street bookshop.
In addition to the above Ian Allan owns the imprint Lewis Masonic. Lewis Masonic produces the ritual books used by UGLE chapters. London: Lower Marsh Birmingham Cardiff Manchester: Piccadilly Station Approach Ian Allan Publishing was well known for its range of enthusiast-based magazines, including the following titles: Hornby Magazine, a monthly magazine aimed at Model Railway Enthusiasts. Despite the title, the magazine covers products of all manufacturers, not just Hornby. Railways Illustrated, a monthly publication targeting enthusiasts. Modern Railways Trains illustrated combined with Locomotive and Carriage & Wagon Review. Modern Locomotives Illustrated Locomotives Illustrated Railway World Buses Buses Illustrated Buses Focus is a spin-off from Buses magazine. No Longer Published. Bus and Coach Preservation was first published in 2001 under the Ian Allan banner following a merger of two previous titles. Vintage Roadscene; this now bi-monthly journal covers the world of historic transport. It has been established for over 20 years.
Aircraft Illustrated was first published in 1968. It covered up to date news and features on civil aviation and preservation. In 2009 the magazine changed its focus to classic aircraft and was renamed Classic Aircraft. Combat Aircraft provides in-depth coverage of the men and the machines at the forefront of the missions undertaken in today’s combat zones. Modern Transport No longer published. Passenger Transport No longer published. Railway Modeller Sold on. Model Railway ConstructorA history of the company and of its publications down to 1967 appeared in the November 1967 edition of their pmagazine Railway World; those magazines still in print were acquired by Key Publishing in March 2012. Through the Lewis Masonic imprint, the company publishes the quarterly masonic magazine "The Square", the longest running masonic periodical in the United Kingdom. From 1962 to 2007 Ian Allan published, jointly with the Light Rail Transit Association, the monthly magazine Modern Tramway—known as Light Rail and Modern Tramway and as Tramways & Urban Transit—and continues to handle printing and some distribution of TAUT, as well as printing of the LRTA's quarterly historical journal, Tramway Review.
Ian Allan Official website
In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels. For road vehicles with more than two axles, the wheelbase is the distance between the steering axle and the centerpoint of the driving axle group. In the case of a tri-axle truck, the wheelbase would be the distance between the steering axle and a point midway between the two rear axles; the wheelbase of a vehicle equals the distance between its rear wheels. At equilibrium, the total torque of the forces acting on a vehicle is zero. Therefore, the wheelbase is related to the force on each pair of tires by the following formula: F f = d r L m g F r = d f L m g where F f is the force on the front tires, F r is the force on the rear tires, L is the wheelbase, d r is the distance from the center of mass to the rear wheels, d f is the distance from the center of gravity to the front wheels, m is the mass of the vehicle, g is the gravity constant. So, for example, when a truck is loaded, its center of gravity shifts rearward and the force on the rear tires increases.
The vehicle will ride lower. The amount the vehicle sinks will depend on counter acting forces, like the size of the tires, tire pressure, the spring rate of the suspension. If the vehicle is accelerating or decelerating, extra torque is placed on the rear or front tire respectively; the equation relating the wheelbase, height above the ground of the CM, the force on each pair of tires becomes: F f = d r L m g − h c m L m a F r = d f L m g + h c m L m a where F f is the force on the front tires, F r is the force on the rear tires, d r is the distance from the CM to the rear wheels, d f is the distance from the CM to the front wheels, L is the wheelbase, m is the mass of the vehicle, g is the acceleration of gravity, h c m is the height of the CM above the ground, a is the acceleration. So, as is common experience, when the vehicle accelerates, the rear sinks and the front rises depending on the suspension; when braking the front noses down and the rear rises.:Because of the effect the wheelbase has on the weight distribution of the vehicle, wheelbase dimensions are crucial to the balance and steering.
For example, a car with a much greater weight load on the rear tends to understeer due to the lack of the load on the front tires and therefore the grip from them. This is why it is crucial, when towing a single-axle caravan, to distribute the caravan's weight so that down-thrust on the tow-hook is about 100 pounds force. A car may oversteer or "spin out" if there is too much force on the front tires and not enough on the rear tires; when turning there is lateral torque placed upon the tires which imparts a turning force that depends upon the length of the tire distances from the CM. Thus, in a car with a short wheelbase, the short lever arm from the CM to the rear wheel will result in a greater lateral force on the rear tire which means greater acceleration and less time for the driver to adjust and prevent a spin out or worse. Wheelbases provide the basis for one of the most common vehicle size class systems; some luxury vehicles are offered with long-wheelbase variants to increase the spaciousness and therefore the luxury of the vehicle.
This practice can be found on full-size cars like the Mercedes-Benz S-Class, but ultra-luxury vehicles such as the Rolls-Royce Phantom and large family cars like the Rover 75 came with'limousine' versions. Prime Minister of the United Kingdom Tony Blair was given a long-wheelbase version of the Rover 75 for official use, and some SUVs like the VW Tiguan and Jeep Wrangler come in LWB models In contrast, coupé varieties of some vehicles such as the Honda Accord are built on shorter wheelbases than the sedans they are derived from. The wheelbase on many commercially available bicycles and motorcycles is so short, relative to the height of their centers of mass, that they are able to perform stoppies and wheelies. In skateboarding the word'wheelbase' is used for the distance between the two inner pairs of mounting holes on the deck; this is different from the distance between the rotational centers
An engine-generator or portable generator is the combination of an electrical generator and an engine mounted together to form a single piece of equipment. This combination is called an engine-generator set or a gen-set. In many contexts, the engine is taken for granted and the combined unit is called a generator. In addition to the engine and generator, engine-generators include a fuel supply, a constant engine speed regulator and a generator voltage regulator and exhaust systems, lubrication system. Units larger than about 1 kW rating have a battery and electric starter motor. Standby power generating units include an automatic starting system and a transfer switch to disconnect the load from the utility power source when there is a power failure and connect it to the generator. Engine-generators are available in a wide range of power ratings; these include small, hand-portable units that can supply several hundred watts of power, hand-cart mounted units, as pictured below, that can supply several thousand watts and stationary or trailer-mounted units that can supply over a million watts.
Regardless of the size, generators may run on gasoline, natural gas, bio-diesel, sewage gas or hydrogen. Most of the smaller units are built to use gasoline as a fuel, the larger ones have various fuel types, including diesel, natural gas and propane; some engines may operate on diesel and gas simultaneously. Many engine-generators use a reciprocating engine, with fuels mentioned above; this can be a steam engine, such as most coal-powered fossil-fuel power plants. Some engine-generators use a turbine as the engine, such as the industrial gas turbines used in peaking power plants and the microturbines used in some hybrid electric buses; the generator voltage and power ratings are selected to suit the load that will be connected. Engine-driven generators fueled on natural gas fuel form the heart of small-scale combined heat and power installations. There are only a few portable three-phase generator models available in the US. Most of the portable units available are single-phase generators and most of the three-phase generators manufactured are large industrial type generators.
In other countries where three-phase power is more common in households, portable generators are available from a few kW and upwards. Portable engine-generators may require an external power conditioner to safely operate some types of electronic equipment. Small portable generators may use an inverter. Inverter models can run at slower RPMs to generate the power, necessary, thus reducing the noise of the engine and making it more fuel-efficient. Inverter generators are best to power sensitive electronic devices such as computers and lights that use a ballast; the mid-size stationary engine-generator pictured here is a 100 kVA set which produces 415 V at around 110 A. It is powered by a 6.7-liter turbocharged Perkins Phaser 1000 Series engine, consumes 27 liters of fuel an hour, on a 400-liter tank. Diesel engines in the UK can rotate at 1,500 or 3,000 rpm; this produces power at 50 Hz, the frequency used in Europe. In areas where the frequency is 60 Hz, generators rotate at 1,800 rpm or another divisor of 3600.
Diesel engine-generator sets operated at their peak efficiency point can produce between 3 and 4 kilowatt hours of electrical energy for each liter of diesel fuel consumed, with lower efficiency at partial loads. Many generators produce enough kilowatts to power anything from a business to a full-sized hospital; these units are useful in providing backup power solutions for companies which have serious economic costs associated with a shutdown caused by an unplanned power outage. For example, a hospital is in constant need of electricity, because several life-preserving medical devices run on electricity, like ventilators. A common use is a railway diesel electric locomotive, some units having over 4,000 hp. Large generators are used onboard ships that utilize a diesel-electric powertrain. Voltages and frequencies may vary in different installations. Engine-generators are used to provide electrical power in areas where utility electricity is unavailable, or where electricity is only needed temporarily.
Small generators are sometimes used to provide electricity to power tools at construction sites. Trailer-mounted generators supply temporary installations of lighting, sound amplification systems, amusement rides etc. You can use a wattage chart to calculate the estimated power usage for different types of equipment to determine how many watts are necessary in a portable generator. Trailer-mounted generators or mobile generators, diesel generators are used for emergencies or backup where either a redundant system is required or no generator is on site. To make the hookup faster and safer, a tie-in panel is installed near the building switchgear that contains connectors such as camlocks; the tie-in panel may contain a phase rotation indicator and a circuit breaker. Camlock connectors are rated for 400 amps up to 480-volt systems and used with 4/0 type W cable connecting to the generator. Tie-in panel designs are common between 200- and 3000-amp applications. Standby electrical generators are permanently installed and used to provide electricity to critical loads during temporary interruptions of the utility power supply.
Hospitals, communications service installations, data processing ce
Brush Traction is a manufacturer and maintainer of railway locomotives, part of Wabtec Corporation, based at Loughborough in Leicestershire, UK, situated alongside the Midland Main railway line. In 1865, Henry Hughes, a timber merchant engineer, began building horse-drawn tramcars and railway rolling stock at the Falcon Works in Loughborough, his first company was known as the Hughes's Tramway Engine Works Ltd.. Records are sparse, but it seems that he began producing steam locomotives about 1867 for the Paris Exhibition, his main business, was tram engines, lightweight steam engines which drew passenger cars, made possible by the Tramways Act 1870. Among these was "The Pioneer" for the Mumbles Railway; these were distinct from those tramcars where the boiler mechanism was an integral part of the passenger car. Amongst the first steam locomotives built there was "Belmont", which ran on the Snailbeach District Railways, three 2 ft 3 in gauge 0-4-0STs for the Corris Railway supplied in 1878; the Corris locomotives are said to have been works numbers 322, 323 and 324, implying that the tram vehicles and steam locomotives were included in a single numerical sequence.
In 1881 Hughes' built two 3 ft gauge 0-4-0STs for the Liverpool Corporation Waterworks Committee for use in the construction of the waterworks at Lake Vyrnwy in Wales. In 1881 the company ran into legal problems and in 1882 it was in receivership. Hughes departed, soon after, for New Zealand, where in collaboration with local engineer E. W Mills, he built small tramway engines. Late in 1882 the company reformed as the Falcon Engine & Car Works Ltd. and supplied three more locomotives of the same design for the railways at Vyrnwy. Again there are few records, but the factory remained busy with both railway and tramway locomotives and rolling stock. Among these were tank locomotives for Ireland and the Azores; some were subcontracts from other firms, such as Kerr Stuart, in Glasgow. In 1889, the assets were acquired by the London based Anglo-American Brush Electric Light Corporation, which moved the 100 miles north into the Falcon Works at Loughborough, under the new name, Brush Electrical Engineering Company Limited.
Between 1901 and 1905 the Brushmobile electric car was developed using a Vauxhall Motors engine, although only six were built. One of these six featured in the film Carry on Screaming. Nearly 100 buses, plus some lorries were built using French engines until 1907. Brush Electrical Engineering built some carriages that were used in the 1900s on the Central London Railway and the City and South London Railway, the respective forerunners of London Underground's Central and Northern lines. In all, about 250 steam locomotives were built in addition to the tram engines. Production finished after World War I and the company concentrated on transport-related electrical equipment, including tramcars and battery-operated vehicles. In World War II Brush Coachworks diversified into aircraft production, building 335 de Havilland Dominies for the Royal Air Force and Fleet Air Arm. Wing sections were built for Lancaster bombers and Hampden fuselages were overhauled; the coachworks continued after the war with omnibus bodies mounted on Daimler chassis using Gardner five-cylinder diesel engines and Daimler preselector gearboxes as well as AEC and BMMO Chassis for Midland Red and 100 Leyland Titans for Birmingham City Transport as well as bodies to the design of the British Electric Traction group on Leyland Royal Tigers.
In 1952 the coachworks were closed and the goodwill and patents were bought by neighbouring Willowbrook. Close to Derby and its railway workshops, it retained its contacts with the railway. Acquired by Heenan & Froude in 1947, it was merged with W. G. Bagnall to produce diesel locomotives. In 1951, the company Brush Bagnall Traction Limited was formed; when British Railways began to replace its fleet of steam engines, Brush entered the market for main line diesel-electric locomotives. In 1957, the Brush group were bought up by Hawker Siddeley; as part of Hawker Siddeley Electric Power Group, it passed to BTR plc and became Brush Traction. It is now part of FKI Energy Technologies; the locomotive works are still occupied by the Brush Traction Company and are in use for the building and repair of locomotives. On 28 February 2011, Wabtec announced. Brush manufactured various diesel and electric locomotives for the British railway network: Class 30 "Brush Type 2" mixed-traffic diesel locomotive. Class 31 "Brush Type 2" mixed-traffic diesel locomotive.
Class 47 "Brush Type 4" mixed-traffic diesel locomotive. Class 53 "Falcon" prototype diesel locomotive. Class 57 re-engineered diesel locomotive. Class 60 heavy freight diesel locomotive. Class 89 prototype electric locomotive. Class 92 dual-voltage electric locomotive, it manufactured the Eurotunnel Class 9 electric locomotives operated by Eurotunnel through the Channel Tunnel. Brush Traction manufactured locomotives for export: 800 bhp A1A-A1A main line diesel-electric locomotives for Ceylon in 1952 1000 bhp Bo-Bo diesel-electric locomotives for Sri Lanka in 1981 Class DE4 1730 bhp Co-Co narrow gauge diesel-electric locomotives for Rhodesia in 1963 Various Bo-Bo diesel electric freight locomotives to Cuba, Gabon, Morocco Battery electric locomotives to Hong Kong EF class heavy freight electric locomotive Class 18 shunter locomotives for Malayan Railways in 1978They were a major supplier of traction equipment to rapid transit systems, in particular, London Und
Bristol Bath Road depot
Bristol Bath Road depot was a railway Traction Maintenance Depot situated in Bristol. Built on the site of the original built Bristol and Exeter Railway shed, it was rebuilt under the Loans and Guarantees Act in 1934 by the Great Western Railway, allocated shed code 82A; the site scale meant that although the depot was to be the major repair and maintenance point for the Bristol divisional area, the shed was restricted to a steel-frame straight 8-road with northernlight roof pattern form, as opposed to the GWR standard-pattern turntable model like Old Oak Common. Secondly, as the depot was so close to Bristol Temple Meads, it was required to keep the depot in full operation while construction took place; the twin-ramp coal stage was of standard GWR pattern but used concrete beams and brick piers to restrict ramp width. The divisional repair shop was located to the far north of the site, close to the River Avon. There were two 65 feet standard-pattern over-girder turntables on site, one to the rear of the shed, one to the Northeast of the repair shop.
While Bath Road handled passenger traffic locomotives, St Philip's Marsh depot on the eastern throat handled freight types. Post nationalisation, under British Railways both Bath Road and St Philip's Marsh gained additional allocation from the closure of the local London Midland and Scottish Railway sheds. By 1950 it had an allocation of 93 locomotives, half of them classic GWR 4-6-0s, most of the others 2-6-2Ts for running local and regional passenger traffic. However, as it was located on a main national route, with an large-scale shed on the opposite throat of the station, Bath Road was one of the first sheds to be closed to steam locomotives from September 1960. Rebuilt as a diesel depot, it retained one of the turntables; the depot ceased all operation on 28 September 1995, when its last operator Great Western Trains transferred all operations to St Philip's Marsh T&RSMD. In 2011, the railway-level depot site was named as part of the 70-hectare Bristol Temple Quarter Enterprise Zone, where reduced taxes and planning controls would encourage development of new businesses.
It was hoped. The site was considered to become the location for the Bristol Arena, a new 12,000 seater entertainment venue, with construction expected to start in late 2016 and set to open in 2018. Development of the Arena was delayed and at the end of 2018, the idea of building it here were scrapped and the future for the site remains unclear. Rail Atlas Great Britain & Ireland, S. K. Baker ISBN 0-86093-553-1 "Rail regulator approves Bristol Bath Road depot closure". RAIL. No. 344. EMAP Apex Publications. 18 November – 1 December 1998. P. 7. ISSN 0953-4563. OCLC 49953699
Steam generator (railroad)
A steam generator is a type of boiler used to produce steam for climate control and potable water heating in railroad passenger cars. The output of a railroad steam generator is low pressure, saturated steam, passed through a system of pipes and conduits throughout the length of the train. Steam generators were developed when diesel locomotives started to replace steam locomotives on passenger trains. In most cases, each passenger locomotive was fitted with a steam generator and a feedwater supply tank; the steam generator used some of the locomotive's diesel fuel supply for combustion. When a steam generator-equipped locomotive was not available for a run, a so-called "heating car" fitted with one or two steam generators was inserted between the last locomotive in the consist and the rest of the train. Steam generators would be fitted to individual cars to enable them to be heated independently of any locomotive supply. In Ireland, Córas Iompair Éireann used "heating cars" as standard and CIÉ diesel locomotives were not fitted with steam generators.
During the early days of passenger railroading, cars were heated by a wood or coal fired stove—if any heat was provided at all. It was difficult to evenly heat the drafty cars. Passengers near the stove found it uncomfortably hot, while those further away faced a cold ride; the stoves were a safety hazard. Cars were ignited by embers from the stove in a wreck, when a dislodged stove would overturn, dumping burning coals into the car; the use of steam from the locomotive to heat cars was first employed in the late 19th century. High pressure steam from the locomotive was passed through the train via hoses; the dangers of this arrangement became evident in the accidents. In 1903 Chicago businessman Egbert Gold introduced the "Vapor" car heating system, which used low pressure, saturated steam; the Vapor system was safe and efficient, became nearly universal in railroad applications. When steam locomotives began to be retired from passenger runs, Gold's company, now known as the Vapor Car Heating Company, developed a compact water-tube boiler that could be fitted into the rear of a diesel locomotive's engine room.
Known as the Vapor-Clarkson steam generator, it and its competitors remained a standard railroad appliance until steam heat was phased out. In 1914-16, the Chicago, Milwaukee & St Paul Railway electrified some 440 miles of their line going over the Rocky Mountains and Cascade Range with the 3 kV DC overhead system; the motive power was EF-1s and EP-1s by American Locomotive Company with electrical equipment by General Electric. These articulated 2-section engines in passenger version were equipped with 2 oil-fired steam boilers, one in each section. In Great Britain, steam generators were built for British Railways diesel locomotives by three firms - Spanner and Stone. All types were notoriously unreliable and failures were common. In Poland Vapor steam generators were fitted to diesel passenger locomotives SP45; the boilers were removed in the 80s and 90s and replaced with 3 kV DC generators driven by main engine, when maintenance became too expensive and remaining cars not fitted with electric heating were withdrawn from service.
The New Zealand electric locomotives class ED, used in and around Wellington, were fitted with oil-fired steam boilers manufactured by the Sentinel Waggon Works. The boilers appeared to have been used rarely and were removed during the locomotives’ operational lives; these burned diesel fuel, a lightweight fuel oil. The term steam generator refers to an automated unit with a long spiral tube that water is pumped through and is surrounded by flame and hot gases, with steam issuing at the output end. There is no pressure vessel in the ordinary sense of a boiler; because there is no capacity for storage, the steam generator's output must change to meet demand. Automatic regulators varied the water feed, fuel feed, combustion air volume. By pumping more water in than can be evaporated, the output was a mixture of steam and a bit of water with concentrated dissolved solids. A steam separator removed the water. An automatic blowdown valve would be periodically cycled to eject solids and sludge from the separator.
This reduced limescale buildup caused by boiling hard water. Scale build-up that occurred had to be removed with acid washouts; the New Zealand ED class electric locomotive used around Wellington from 1940 had oil-fired water tube boilers for passenger carriage steam heaters, which were removed. Diesel-hauled passenger trains like the Northerner on the North Island Main Trunk had a separate steam heating van, but the carriages of long distance trains like the Overlander used electric heaters supplied by a separate power or combined power-luggage van. In British electric locomotives the steam generator was an electric steam boiler, heated by a large electric immersion heater running at the line voltages of 600 volts from a third rail or 1,500 volts from an overhead wire; the Polish electric locomotive EL204 of 1937 was fitted with an electric steam generator supplied from overhead lines. The locomotive was destroyed during the second world war. Steam heated or cooled rail cars have been replaced or converted to electric systems.
Wisps of steam issuing from normal service cars are now history in the UK, USA, much of the rest of the world. In the UK, much preserved stock, including mail-line certified railtour sets, still retains steam heating capability as well as electric heating, this is still sometimes used when the trains are being operated by steam locomotives or pres
A traction motor is an electric motor used for propulsion of a vehicle, such as Locomotives or electric roadway vehicle. Traction motors are used in electrically powered rail vehicles and other electric vehicles including electric milk floats, roller coasters and trolleybuses, as well as vehicles with electrical transmission systems, battery electric vehicles. Direct-current motors with series field windings are the oldest type of traction motors; these provided a speed-torque characteristic useful for propulsion, providing high torque at lower speeds for acceleration of the vehicle, declining torque as speed increased. By arranging the field winding with multiple taps, the speed characteristic could be varied, allowing smooth operator control of acceleration. A further measure of control was provided by using pairs of motors on a vehicle. Where higher speed was desired, these motors could be operated in parallel, making a higher voltage available at each and so allowing higher speeds. Parts of a rail system might use different voltages, with higher voltages in long runs between stations and lower voltage near stations where only slower operation was needed.
A variant of the DC system was the AC operated series motor, the same device but operated on alternating current. Since both the armature and field current reverse at the same time, the behavior of the motor is similar to that when energized with direct current. To achieve better operating conditions, AC railways were supplied with current at a lower frequency than the commercial supply used for general lighting and power; the AC system allowed efficient distribution of power down the length of a rail line, permitted speed control with switchgear on the vehicle. AC induction motors and synchronous motors are simple and low maintenance, but are awkward to apply for traction motors because of their fixed speed characteristic. An AC induction motor only generates useful amounts of power over a narrow speed range determined by its construction and the frequency of the AC power supply; the advent of power semiconductors has made it possible to fit a variable frequency drive on a locomotive. Traditionally road vehicles have used diesel and petrol engines with a mechanical or hydraulic transmission system.
In the latter part of the 20th century, vehicles with electrical transmission systems began to be developed—one advantage of using electric machines is that specific types can regenerate energy —providing deceleration as well as increasing overall efficiency by charging the battery pack. Traditionally, these were series-wound brushed DC motors running on 600 volts; the availability of high-powered semiconductors has now made practical the use of much simpler, higher-reliability AC induction motors known as asynchronous traction motors. Synchronous AC motors are occasionally used, as in the French TGV. Before the mid-20th century, a single large motor was used to drive multiple driving wheels through connecting rods that were similar to those used on steam locomotives. Examples are FF1 and L5 and the various Swiss Crocodiles, it is now standard practice to provide one traction motor driving each axle through a gear drive. The traction motor is three-point suspended between the bogie frame and the driven axle.
The problem with such an arrangement is that a portion of the motor's weight is unsprung, increasing unwanted forces on the track. In the case of the famous Pennsylvania Railroad GG1, two bogie-mounted motors drove each axle through a quill drive; the "Bi-Polar" electric locomotives built by General Electric for the Milwaukee Road had direct drive motors. The rotating shaft of the motor was the axle for the wheels. In the case of French TGV power cars, a motor mounted to the power car’s frame drives each axle. By mounting the heavy traction motor directly to the power car's frame, rather than to the bogie, better dynamics are obtained, allowing better high-speed operation; the DC motor was the mainstay of electric traction drives on both electric and diesel-electric locomotives, street-cars/trams and diesel electric drilling rigs for many years. It consists of two parts, a rotating armature and fixed field windings surrounding the rotating armature mounted around a shaft; the fixed field windings consist of wound coils of wire fitted inside the motor case.
The armature is another set of coils wound round a central shaft and is connected to the field windings through "brushes" which are spring-loaded contacts pressing against an extension of the armature called the commutator. The commutator collects all the terminations of the armature coils and distributes them in a circular pattern to allow the correct sequence of current flow; when the armature and the field windings are connected in series, the whole motor is referred to as "series-wound". A series-wound DC motor has a low resistance armature circuit. For this reason, when voltage is