The automobile transmission system is located between the engine and the driving wheel, which can make the power characteristics of the engine output suitable for the needs of automobile driving under various working conditions, so that the automobile can run normally. The most common is the mechanical transmission system, hydraulic machinery transmission system for large buses, senior cars and all kinds of engineering vehicles. Electric drives are rare and are only used in large mine vehicles. It is mainly composed of clutch, transmission, universal transmission device and drive axle. In off-road vehicles, it also has a sub-brake. Responsible for distributing transmission power back to each drive axle.

The structural characteristics of the main assemblies

I. Clutch:

The clutch is located between the engine flywheel and transmission. The driving part is fixed on the rear end face of the flywheel, the driven part is located between the flywheel and the pressure plate, and is connected with the first shaft of the transmission through the spline hole in the center. The pressing part is located between the pressure plate and the clutch cover, and the friction plate is tightly clamps between the flywheel and the pressure plate by its elastic force. The main and slave parts use the friction torque to transfer the torque output by the engine. The separation mechanism is composed of a separation lever mounted on the clutch cover and the pressure plate, a separation bearing mounted on the sleeve of the bearing cover of the first shaft of the transmission and a separation fork mounted on the flywheel housing. The separation fork is mechanically or hydraulically connected to the clutch pedal in the cockpit. The clutch is often engaged to transfer torque, only when the clutch pedal is stepped on, the separation mechanism will move the pressure plate back and separate the friction plate and present the separation state. At this time, torque transmission is interrupted, and operations such as starting, shifting, braking and so on can be carried out. When the car driveline overload, the clutch will start to slip, the transmission to achieve overload protection. The friction plate is also provided with a torque shock absorber to make the transmission work more stable. The clutch pressing part of the traditional structure mostly adopts a circle of spiral spring distributed uniformly around the circumference. In addition to the clutch when more laborious, elastic is not easy to uniform. There are also disadvantages such as large axial size and decreasing compression force at high speed, which are gradually replaced by diaphragm clutch. Diaphragm clutches use a dish-shaped diaphragm spring instead of a coiled spring and a disengaging lever, which not only reduces the axial ruler, but is also easy to handle and reliably compacts under all conditions. The operation mechanism of the clutch refers to the transmission part between the clutch pedal and the separation fork. Most cars are mechanically built, connected to each other by a pull rod or wire rope. There are also some vehicles that use hydraulic mechanisms, which connect the two with a hydraulic transmission.

Two, transmission:

In the car running, the variation range of the required driving force is very large, but the variation range of the engine output torque is limited. The transmission must be used to make the engine output torque range to meet the needs of the vehicle running. At the same time, the transmission should also be able to achieve the car reversing and engine idling. At present, mechanical grade transmission is used in automobiles, which is composed of variable speed transmission mechanism and variable speed control mechanism. Generally with 3 ~ 6 forward gear and 1 reverse gear. Each gear has a gear ratio, which can increase the engine output torque to the same multiple as the gear ratio. At the same time, reduce the engine speed to the same multiple as the transmission ratio. The lower the gear, the greater the transmission ratio.

III. Universal transmission device:

The universal transmission device is mainly composed of the universal joint and the transmission shaft, which transmits the power from the transmission or the sub-brake to the drive axle.

IV. Main Reducer:

Used to further increase the torque output of the transmission, and further reduce the speed. For a longitudinal engine, the rotation plane is also rotated by 90 degrees to be parallel to the wheel plane.

V. Differential:

The differential set on the drive axle can allow the speed of both driving wheels to be out of sync when necessary, so as to meet the needs of car steering and irregular road driving.

VI. Semi-axis:

The inner end of each half shaft is connected with the half shaft gear through a spline, and the outer end is connected with the wheel hub machine.

7. Axle housing and hub:

The axle housing forms the housing of the drive axle. The hub is the part of the wheel through which the wheel is mounted on the drive axle.