What Is Overdoor Traction?

In mechanical engineering, traction means that the transmission system of wheeled vehicle carriers, including automobiles, railway locomotives, and bicycles, generates rotational torque on the wheels, which is generated through the interaction between the moving wheel and the ground or rails.

Middle school physics often mentions cars, trucks, trains and bicycles

In the following description, f, f1, f2, f3, f3 ', and F are used to represent the magnitude of the force, and they are all positive values.

When the engine is not working and the car continues to move forward, the force on the air f1 is backward, and the ground is facing the level of the driven wheel

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Middle school physics often mentions that the traction of cars, bicycles, trains and other vehicles should refer to the combined force exerted by the transmission system on the wheels of the car body. Some people think that traction is the force exerted on the driving wheels by the transmission system, which is incorrect. Take the bicycle as an example, the load of the bicycle is shared by two wheels. Without considering other factors, the friction factor is used for analysis, and the front wheels also need external power. Traction should be the sum of the friction of the two wheels. Others believe that "the friction of the front wheels is backward,

The calculation of traction is particularly common in railway locomotives and is one of the important performance indicators. The traction force of locomotive in actual application can be divided into several types according to the force transmission process. The tangential outward force generated by the force on the periphery of the moving wheel is called the traction force on the periphery of the locomotive; The traction force of a traction train is equal to the wheel traction force minus the total running resistance of the locomotive. According to the working state of the vehicle, the traction can be divided into starting traction, continuous traction and maximum traction. Starting tractive force refers to the tractive force that can be emitted when the vehicle starts from a stationary state, and its performance is limited by adhesion; maximum tractive force refers to the maximum tractive force that the vehicle can emit without damaging its own machinery, and its value is usually the same as the starting tractive force ; Continuous traction is the corresponding traction of the vehicle at continuous speed. By calculating the relationship between speed ( v ), power ( P ), and force ( F ) (formula P = vF ), it can be found that with the same power, the traction force is inversely proportional to the speed of movement. The relationship between traction and speed can be displayed through the traction curve. The figure on the right is a schematic diagram of a typical traction curve. Line AB is the maximum traction force that the locomotive can play at the start. After reaching point B of continuous speed, it is the constant power area. Rated power, while traction decreases with speed.