What are the types of semi-axle commonly used in cars

Update:07-07-2021

Summary:

The automobile half shaft is the drive shaft. When the […]

The automobile half shaft is the drive shaft. When the car is turning, the left and right wheels have different trajectory radii, so the distance they pass when turning is also different. The outer wheel has to pass a longer distance. If the power is transmitted to the same size wheel through a complete shaft, the two wheels The rotation speed is the same, the diameter is the same, and the distance traveled by the two wheels is different when turning. Then the wheels on the inner side of the curve need to be slipped and idling (not walking), causing turning difficulties; in order to overcome and improve this problem, the vehicle drive shaft is divided into The two halves are separated from the left and right, and the middle is connected by a "differential". When the vehicle is driving straight, the two wheels can get the same driving force. When turning, due to the action of the differential, the rotation speed of the inner wheel is lower than that of the outer wheel. In this way, the goal of driving the vehicle forward by the two wheels at the same time is achieved, but the movement distance of the outer wheels is larger than the inner side. The use of two half shafts for the drive shaft is designed to improve the turning performance of the vehicle.
The half-axes commonly used in modern cars are classified into full-floating and semi-floating according to their different supporting types. (There are also three types, namely full-floating, 3/4-floating, and semi-floating)

Full floating half shaft
The semi-axle that only bears torque when working, and does not bear any force or bending moment at its two ends is called a full-floating semi-axle. The outer flange of the half shaft is fastened to the hub with bolts, and the hub is mounted on the half shaft sleeve through two bearings far apart. Structurally, the inner end of the full-floating half shaft is made of splines, the outer end is made of flanges, and there are several holes on the flanges. Because of its reliable work, it is widely used in commercial vehicles.
3/4 floating half shaft
In addition to bearing the full torque, it also bears part of the bending moment. The most prominent structural feature of the 3/4 floating half shaft is that there is only one bearing at the outer end of the half shaft, which supports the wheel hub. Due to the poor supporting rigidity of a bearing, in addition to the torque, this kind of semi-axle also bears the bending moment caused by the vertical force, driving force and lateral force between the wheel and the road surface. 3/4 floating half shafts are rarely used in automobiles.
Semi-floating half shaft
The semi-floating half shaft is directly supported on the bearing located in the inner hole of the outer end of the axle housing with a journal close to the outer end. The wheel disc and the brake hub are connected. Therefore, in addition to transmitting torque, it must also bear the bending moment caused by the vertical force, driving force and lateral force transmitted by the wheel. Semi-floating half axles are used in passenger cars and some cars with same use due to their simple structure, low quality and low cost.