Transmission is composed of transmission organization and operation organization. When required, power take-off can be added. There are two ways of classification: according to the transmission ratio change method and according to the different operation method.

　　According to the change method of transmission ratio:

　　Stepwise transmission was widely used at that time. It adopts gear transmission and has several constant transmission ratios. According to the type of gear train used, there are two kinds of axial fixed transmission (general transmission) and axial rotary transmission (planetary transmission). At that time, the transmission ratios of cars, light and medium goods vehicles generally had 3-5 forward gears and one reverse gear. In the combined transmission for heavy goods vehicles, there were more gears. The number of transmission gears refers to the number of driving gears.

　　The transmission ratio of CVT can be changed according to multi-level in a specific numerical plan. There are two common types: electric type and hydraulic type (dynamic hydraulic type). The variable speed transmission part of electric CVT is DC series motor. In addition to the application in trolley bus, it is also widely used in the transmission system of super heavy dump truck. The transmission component of the dynamic hydraulic continuously variable transmission is the hydraulic torque converter.

　　Integrated transmission is a kind of hydro mechanical transmission composed of hydraulic torque converter and gear type step transmission. Its transmission ratio can be changed steplessly in several successive plans between large value and small value, which is widely used at that time.

　　According to the operation method:

　　The forced operation transmission relies on the driver to operate the shift lever directly.

　　The transmission ratio selection and shift of automatic operation transmission are automatic. The so-called "automatic" means that the shift of each gear of mechanical transmission is completed by controlling the implementing elements of shift system by means of signal system reflecting engine load and vehicle speed. The driver only needs to operate the accelerator pedal to control the speed.

　　There are two types of semi-automatic transmission: one is the automatic operation of several commonly used gears, and the other gears are operated by the driver; The other is preselected, that is, the driver selects the gear with the button in advance, and when pressing the clutch pedal or releasing the accelerator pedal, switches on an electromagnetic device or hydraulic device to shift gears.

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