In the automobile axle, the front axle is mainly used for steering, also known as the front axle. In the axle Market, the front axle accounts for about 33% of the axle sales, and the front axle with driving function accounts for a very small proportion. It is only used in military vehicles, petroleum, mining and field operation vehicles under special working conditions. The rear axle is mainly a drive axle, which is mainly used to reduce speed, increase torque and change the direction of power transmission. The rear axle can be divided into single-stage reduction drive axle and double-stage reduction drive axle. The double-stage reduction drive axle is divided into central double stage reduction drive axle and central and wheel side double stage reduction drive axle.
1. Central single reduction drive axle
The central single unit reduction drive axle is the simplest one of the drive axle structures. A quasi hyperbolic spiral bevel gear is used to reduce the speed and increase the torque at the central axle package. It has the advantages of simple structure, light weight and easy assembly. Generally, the single unit reduction axle is used when the main transmission ratio is less than 6. For some heavy trucks with large load, large reduction ratio is required. If single-stage reduction drive axle is adopted, the diameter of driven gear must be increased, which will affect the ground clearance of drive axle and reduce the trafficability of the whole axle. Therefore, it is necessary to use double reduction drive axle at this time.
2. Central double reduction drive axle
At present, in the domestic axle Market, there are mainly two types of central double reduction drive axle: one is to reserve space in the single-stage reducer. When the traction and speed ratio are required to be increased, a cylindrical planetary gear reduction mechanism is installed, and the original central single-stage reduction is replaced by central double reduction. The axle housing and main reducer can be interchanged; The other is that the first stage bevel gear needs to be reformed, and then the second stage spur gear or helical gear needs to be installed to become a central two-stage drive axle. As a derivative product, the use of the central double reduction drive axle is limited to a certain extent, so it is generally not developed as a basic type of bridge, but only as a derivative special drive axle.
3. Central single stage, wheel side reduction drive axle
The wheel side reduction drive axle is composed of the central one-stage reduction and the wheel side one-stage reduction. At present, the wheel reduction drive axle can be divided into two types: Bevel planetary gear type wheel reduction axle and cylindrical planetary gear type wheel reduction axle. The main difference is that the structure of the wheel planetary gear is different. Due to the existence of one-stage wheel side deceleration, the torque transmitted by the half axle is reduced, and the increased torque is directly added to the wheel side reducer at the axle head. Moreover, due to the existence of wheel side deceleration, the size of the central bridge package can be reduced to ensure the high trafficability of the vehicle. Compared with the single-stage axle, it has complex structure, heavy weight, high price, and the wheel side reducer has gear transmission, which will produce a lot of heat when driving for a long time, resulting in overheating of the hub. Therefore, as a highway vehicle drive axle, it is not as good as the single-stage reducer. The wheel side reducer drive axle is mainly used in engineering vehicles, mining vehicles and other non highway vehicles.