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Locomotive Wheelslip
{{Unreferenced , date=September 2013 Locomotive wheelslip is an event that affects railway motive power usually when starting from stationary, but can also affect an engine in motion. Overview The greatest effort is required from a locomotive when starting. At this time, if the engineer applies too much power to the wheels (i.e., for a steam locomotive, the engineer opens the regulator too far) the turning force applied to the wheel will greatly exceed the opposing friction force affected by the surface of the rail, and the wheel will turn without being able to move the train forward. If the engineer does not take quick corrective action (i.e. by closing the regulator) the locomotive can end up stationary with its wheels spinning: this can damage both the locomotive drive mechanism, through running too fast, and the rail surface, which, in extreme cases, can be left with a dip where the spin took place. (Such a dip is dangerous if not repaired subsequently.) Some locomotive types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway
Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a prepared flat surface, rail vehicles (rolling stock) are directionally guided by the tracks on which they run. Tracks usually consist of steel rails, installed on sleepers (ties) set in ballast, on which the rolling stock, usually fitted with metal wheels, moves. Other variations are also possible, such as "slab track", in which the rails are fastened to a concrete foundation resting on a prepared subsurface. Rolling stock in a rail transport system generally encounters lower frictional resistance than rubber-tyred road vehicles, so passenger and freight cars (carriages and wagons) can be coupled into longer trains. The operation is carried out by a railway company, providing transport between train stations or freight customer facilit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traction (engineering)
Traction, or tractive force, is the force used to generate motion between a body and a tangential surface, through the use of dry friction, though the use of shear force of the surface is also commonly used. Traction can also refer to the ''maximum'' tractive force between a body and a surface, as limited by available friction; when this is the case, traction is often expressed as the ratio of the maximum tractive force to the normal force and is termed the ''coefficient of traction'' (similar to coefficient of friction). It is the force which makes an object move over the surface by overcoming all the resisting forces like friction, normal loads(load acting on the tiers in negative 'Z' axis), air resistance, rolling resistance, etc. Definitions Traction can be defined as: In vehicle dynamics, tractive force is closely related to the terms tractive effort and drawbar pull, though all three terms have different definitions. Coefficient of traction The ''coefficient of traction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wheel Speed Sensor
A wheel speed sensor (WSS) or vehicle speed sensor (VSS) is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup. Automotive wheel speed sensor Purpose The wheel speed sensor was initially used to replace the mechanical linkage from the wheels to the speedometer, eliminating cable breakage and simplifying the gauge construction by eliminating moving parts. These sensors also produce data that allows automated driving aids like ABS to function. Construction The most common wheel speed sensor system consists of a ferromagnetic toothed reluctor ring (tone wheel) and a sensor (which can be passive or active). The tone wheel is typically made of steel and may be an open-air design, or sealed (as in the case of unitized bearing assemblies). The number of teeth is chosen as a trade-off between low-speed sensing/accuracy and high-speed sensing/cost. Greater numbers of teeth will req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Locomotive
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or gas turbines, are classed as diesel-electric or gas turbine-electric and not as electric locomotives, because the electric generator/motor combination serves only as a power transmission system. Electric locomotives benefit from the high efficiency of electric motors, often above 90% (not including the inefficiency of generating the electricity). Additional efficiency can be gained from regenerative braking, which allows kinetic energy to be recovered during braking to put power back on the line. Newer electric locomotives use AC motor-inverter drive systems that provide for regenerative braking. Electric locomotives are quiet compared to diesel locomotives since there is no engine and exhaust noise and less mechanical noise. The lack of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diesel Locomotive
A diesel locomotive is a type of railway locomotive in which the prime mover is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving wheels. Early internal combustion locomotives and railcars used kerosene and gasoline as their fuel. Rudolf Diesel patented his first compression-ignition engine in 1898, and steady improvements to the design of diesel engines reduced their physical size and improved their power-to-weight ratios to a point where one could be mounted in a locomotive. Internal combustion engines only operate efficiently within a limited power band, and while low power gasoline engines could be coupled to mechanical transmissions, the more powerful diesel engines required the development of new forms of transmission. This is because clutches would need to be very large at these power levels and would not fit in a standard -wide locomotive frame, or wear too quic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandite
Sandite is a substance used on railways in the UK, Ireland, US, the Netherlands and Belgium to combat leaves on the line, which can cause train wheels to slip and become damaged with flat spots. Sandite consists of a mixture of sand, antifreeze and steel shot. Leaf build up on the railhead can also cause signalling issues and 'disappearing trains' on the rail control systems (because of the electrically insulating effect of the leaves, which can prevent operation of track circuits). British Rail conducted research, in 1976, to determine the suitability of Sandite for use as an adhesion improver. Application Sandite is usually applied by a special train which first clears fallen leaves from the rails using high-pressure water, then sprays the sandite onto the rail surface. To assist the staff on the Sandite train in locating the sites concerned, in England and Wales black on yellow lineside markers were installed: *The first sign, with three stripes gives advance warning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandbox (railways)
A sandbox is a container on most locomotives, multiple units and trams that holds sand, which is dropped on the rail in front of the driving wheels in wet and slippery conditions and on steep grades to improve traction. Sand delivery The sand may be delivered by gravity, by a steam-blast ( steam locomotives) or by compressed air. Gravity sanding requires that the sand be dry so that it runs freely. Locomotives use multiple sandboxes, so that their delivery pipes could be short and nearly vertical. Engine sheds in the UK were equipped with sand drying stoves, so that sandboxes could be refilled each morning with dry sand. Steam locomotives in the US had a single sandbox, called a sand dome, atop the boiler where the rising heat helped to dry the sand. Even with this arrangement, sand pipes tended to clog, and by the 1880s, pneumatic sanding systems were being proposed. Steam sanding The development of steam sanding was influential on locomotive design. As the sand could then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Train Wheel
A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. The wheel acts as a rolling component, typically press fitted onto an axle and mounted directly on a railway carriage or locomotive, or indirectly on a bogie (in the UK), also called a ''truck'' (in North America). The powered wheels under the locomotive are called driving wheels. Wheels are initially cast or forged and then heat-treated to have a specific hardness. New wheels are machined using a lathe to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly profiled wheels and worn wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment. The International Union of Railways has defined a standard wheel diameter of , although smaller sizes are used in some rapid transit railway systems and on ro-ro carriages. Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power (physics)
In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. In older works, power is sometimes called ''activity''. Power is a scalar quantity. Power is related to other quantities; for example, the power involved in moving a ground vehicle is the product of the aerodynamic drag plus traction force on the wheels, and the velocity of the vehicle. The output power of a motor is the product of the torque that the motor generates and the angular velocity of its output shaft. Likewise, the power dissipated in an electrical element of a circuit is the product of the current flowing through the element and of the voltage across the element. Definition Power is the rate with respect to time at which work is done; it is the time derivative of work: P =\frac where is power, is work, and is time. If a constant force F is applied throughout a distance x, the wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acceleration
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the ''net'' force acting on that object. The magnitude of an object's acceleration, as described by Newton's Second Law, is the combined effect of two causes: * the net balance of all external forces acting onto that object — magnitude is directly proportional to this net resulting force; * that object's mass, depending on the materials out of which it is made — magnitude is inversely proportional to the object's mass. The SI unit for acceleration is metre per second squared (, \mathrm). For example, when a vehicle starts from a standstill (zero velocity, in an inertial frame of reference) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the vehicle turns, an acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power-to-weight Ratio
Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power source. It is also used as a measurement of performance of a vehicle as a whole, with the engine's power output being divided by the weight (or mass) of the vehicle, to give a metric that is independent of the vehicle's size. Power-to-weight is often quoted by manufacturers at the peak value, but the actual value may vary in use and variations will affect performance. The inverse of power-to-weight, weight-to-power ratio (power loading) is a calculation commonly applied to aircraft, cars, and vehicles in general, to enable the comparison of one vehicle's performance to another. Power-to-weight ratio is equal to thrust per unit mass multiplied by the velocity of any vehicle. Power-to-weight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
