Detailed explanation of the transmission system of the automobile chassis structure

The function of the chassis is to support and install the automobile engine and its components and assemblies to form the overall shape of the automobile, and to receive the power of the engine to make the automobile move and ensure normal driving. The chassis consists of four parts: the transmission system, the running system, the steering system and the braking system.

Figure 1 Automobile chassis

Transmission system The transmission system is generally composed of clutch, transmission, universal transmission device, main reducer, differential and half shafts. Function of transmission system The power generated by the automobile engine is transmitted to the driving wheels by the transmission system. The transmission system has the functions of deceleration, speed change, reversing, power interruption, inter-wheel differential and inter-axle differential. It works with the engine to ensure the normal driving of the automobile under various working conditions and has good power and economy. Types and components of transmission system

The transmission system can be divided into mechanical transmission, hydraulic transmission, hydraulic transmission, electric transmission, etc. according to the different energy transmission methods .

1. Schematic diagram of the general composition and layout of the mechanical transmission system (see Figure 2).

Figure 2 Schematic diagram of the layout of the engine in the front, longitudinal position, and rear-wheel drive. Schematic diagram of the layout of a 4×2 car with a traditional engine longitudinally installed in the front of the car and rear-axle drive. The power from the engine is transmitted to the drive axle through the clutch, transmission, and universal joint. At the drive axle, the power is transmitted to the drive wheels through the main reducer, differential, and half shafts.

Figure 3 Schematic diagram of the front-mounted, longitudinally mounted engine and front-wheel drive. The front-mounted, longitudinally mounted engine and front-axle drive make the transmission and the final reducer connected together, eliminating the universal joint between them, as shown in Figure 3. 2. Schematic diagram of a typical hydromechanical transmission (as shown in Figure 4).

1-Hydraulic torque converter 2-Automatic transmission 3-Universal transmission 4-Drive axle 5-Final reducer 6-Drive shaft Figure 4 Schematic diagram of hydromechanical transmission Hydrodynamic transmission (here only refers to hydrodynamic transmission) uses the change of kinetic energy of the liquid medium during the circulation between the active element and the driven element to transmit power. The hydrodynamic transmission device is connected in series with a stepped mechanical transmission. Such a transmission is called hydromechanical transmission. 3. Schematic diagram of hydrostatic transmission system (as shown in Figure 5).

1- Clutch 2- Oil pump 3- Control valve 4- Hydraulic motor 5- Drive axle 6- Oil pipe Figure 5 Schematic diagram of hydrostatic transmission system Hydraulic transmission, also known as hydrostatic transmission, transmits energy through the change of static pressure energy of liquid transmission medium. It is mainly composed of engine-driven oil pump, hydraulic motor and control device.

4. Electric transmission used in hybrid electric vehicles (as shown in Figure 6).

1- Clutch 2- Generator 3- Controller 4- Motor 5- Drive axle 6- Wire Figure 6 The electric drive used in hybrid electric vehicles is that the engine drives the generator to generate electricity, and then the motor drives the drive axle or the motor directly drives the drive wheel with a reducer.

Transmission system layout

The common layout of mechanical transmission system is mainly related to the location of the engine and the drive type of the car. It can be divided into:

1. Front-engine rear-drive - FR: The engine is placed in front and the rear wheels are driven. This is a traditional layout. Most trucks, some cars and some buses at home and abroad adopt this layout. It is front-wheel steering and rear-wheel drive. The engine output power is transmitted to the drive axle through the clutch-transmission-drive shaft, and then transmitted to the left and right half-axles at the rear after deceleration and torque increase, driving the rear wheels to make the car run. The front and rear wheels perform their respective functions, steering and driving are separated, and the load distribution is relatively uniform.

2. Rear-mounted rear-wheel drive - RR: This layout is mostly used in large buses, and a small number of micro and light cars also use this layout. The rear-mounted engine makes it difficult for the front axle to be overloaded, and can make more full use of the vehicle compartment area. It can also effectively reduce the height of the vehicle floor or make full use of the space under the middle floor of the car to place luggage, which is also conducive to reducing the impact of the engine's high temperature and noise on the driver. The disadvantage is that the engine has poor heat dissipation conditions, and some faults during driving are not easy to be detected by the driver. Remote control also makes the control mechanism complicated and inconvenient to repair and adjust. However, due to its outstanding advantages, it is increasingly used in large buses.

3. Front-engine front-wheel drive - FF: The engine is placed in front and the front wheels are driven. This type of layout has a simple control mechanism and good engine heat dissipation conditions. However, when going uphill, the mass of the car moves backward, which reduces the adhesion mass of the front drive wheel and makes the drive wheel slip easily. When braking downhill, the mass of the car moves forward, the front wheel is overloaded, and it is easy to roll over at high speed. Most cars now adopt this layout.

4. Transmission system of off-road vehicles Off-road vehicles are generally all-wheel drive, with the engine in front and a transfer case behind the gearbox to transmit power to all wheels. At present, light off-road vehicles generally use 4×4 drive type, medium-sized off-road vehicles use 4×4 or 6×6 drive type; heavy off-road vehicles generally use 6×6 or 8×8 drive type.