How do the various parts of the car chassis work?

- Apr 13, 2020-

01.manual transmission

Manual transmission is called manual transmission (MT for short), also known as mechanical transmission, that is, the gear lever in the transmission must be moved by hand to change the gear meshing position and the transmission ratio, so as to achieve the purpose of speed change.

It has a simple structure, reliable performance, low manufacturing and maintenance costs, and high transmission efficiency (theoretically, it will be more fuel-efficient). In addition, because it is purely mechanical control, the shift response is fast, and the driver's wishes can be more directly expressed, so It is also more fun to drive, these are the advantages of the manual transmission. However, compared with the automatic gearbox, its operation is cumbersome, and the obvious disadvantage of stumbling when shifting gears is also irreparable.


The clutch is located in the flywheel housing between the engine and the gearbox. The clutch assembly is fixed on the rear plane of the flywheel with screws. The output shaft of the clutch is the input shaft of the gearbox.

During the driving of the car, the driver can step on or release the clutch pedal as needed to temporarily disengage and gradually engage the engine and the transmission to cut off or transfer the power input from the engine to the transmission.

The role of the clutch is to enable the engine and the transmission to be gradually engaged to ensure the smooth start of the car; temporarily cut off the connection between the engine and the transmission, so as to facilitate gear shifting and reduce the impact of gear shifting; when the car is emergency braking can be separated Function to prevent overloading of transmission systems such as transmissions, thus playing a certain protective role.


The car differential can make the left and right (or front and rear) drive wheels rotate at different speeds. It is mainly composed of left and right side shaft gears, two planetary gears and gear racks.

The function is to make the left and right wheels roll at different speeds when the car is turning or driving on uneven roads, that is, to ensure that the driving wheels on both sides are in a pure rolling motion. The differential is installed to adjust the rotation speed difference between the left and right wheels.

In a four-wheel drive, in order to drive four wheels, all wheels must be connected. If the four wheels are mechanically connected together, the car cannot rotate at the same speed when driving in a curve. The rotation speed is basically the same. At this time, it is necessary to add an intermediate differential to adjust the rotation speed difference of the front and rear wheels. suspension system

A suspension system is the general name of all the force-transmitting connection devices between the frame of the car and the axle or wheels. Its function is to transmit the force and torsion acting between the wheels and the frame, and the buffer is transmitted from the uneven road to the frame. Or the impact of the body, and dampen the resulting vibration to ensure that the car can run smoothly.

The function of the suspension system is to support the body and improve the feeling of riding. Different suspension settings will make the driver have different driving experiences. The seemingly simple suspension system combines multiple forces and determines the stability, comfort, and safety of the car.

The typical suspension system structure is composed of elastic elements, guide mechanisms, and shock absorbers, etc., and individual structures also have buffer blocks and lateral stabilizer bars. The elastic elements are also in the form of leaf springs, air springs, coil springs, and torsion bar springs, while modern car suspension systems mostly use coil springs and torsion bar springs, and some premium cars use air springs.

05.Universal joint

The universal joint (that is, the universal joint) is a mechanism that realizes variable-angle power transmission. It is used to change the position of the transmission axis. It is the "joint" part of the universal transmission device of the automobile drive system.

The combination of the universal joint and transmission shaft is called a universal joint transmission device. On vehicles with front-engine rear-wheel drive, the universal joint transmission is installed between the transmission output shaft and the input axle of the final axle of the drive axle; while vehicles with front-engine front-wheel-drive omit the transmission shaft and the universal joint is installed Between the half axle of the front axle and the wheels that are responsible for both driving and steering.

06.Drum brake

Drum brakes are brake devices that use stationary brake pads in the brake drum to remove the brake drum that rotates with the wheel to generate friction to reduce the wheel's rotational speed.

When the brake pedal is depressed, the force of the foot will cause the piston in the master cylinder to push the brake fluid forward and generate pressure in the oil circuit. The pressure is transmitted to the brake cylinder piston of each wheel via the brake oil, and the piston of the brake cylinder pushes the brake pads outward, causing friction between the brake pads and the inner surface of the brake drum, and generating sufficient friction to reduce the speed of the wheels. In order to achieve the purpose of braking.

07.Disc brake

Disc brakes are composed of a brake disc connected to the wheel and brake calipers on the edge of the disc. When braking, high-pressure brake fluid pushes the brake pads to clamp the brake discs to produce a braking effect.

The working principle of the disc brake braking system is to install a disc that rotates synchronously with the wheel on the hub, and install a caliper on the front fork and the frame, and then clamp the disc through the brake block in the caliper to achieve the purpose of braking.

08.Front Front Drive

Front-front drive refers to the drive mode of the front of the engine and front-wheel drive. In the modern medium and small cars, front-drive is mostly used.

The advantage is that the mechanism is simple, and the transmission shaft that transmits power from the front motor to the driving rear wheel is saved compared with the front rear-drive, which saves fuel.

09.Front and rear-drive

The front and rear drive is the front and rear-wheel drive of a car engine. It is the most traditional form of drive.

There are few small cars that use the front and rear drive at home and abroad, but most freight cars (including pickups), some cars (especially high-end cars, racing cars and sports cars) and some passenger cars use front and rear drive.

09 Front four-wheel drive

Front four-wheel drive means the engine is placed on the front of the car and the whole car is driven by four wheels. Because all four wheels have power, the front four-wheel drive has a higher handling performance than the design that only drives on the front or rear wheels.

This layout is commonly used in rally and off-road vehicles. The more well-known front-wheel-drive systems include the Audi Quattro and off-road road sports utility vehicles that were famous in the rally in the 1980s.