The through-type main reducer can be divided into single-stage and double-stage according to its deceleration form. The single-stage through-type main reducer has the advantages of simple structure, small size and small mass, and can make most parts of the middle and rear axles, especially the main parts such as automobile axle housings and half axles interchangeable. Generally not used on the bridge, mainly used in light multi-bridge drive cars.
????According to the different types of reduction gears, the single-stage through-type main reducer can be divided into two structures: hyperbolic gear type and worm gear type. The hyperbolic gear type single-stage through-type main reducer utilizes the feature of the hypoid gear secondary axis offset to pass a through shaft through the middle axle and to the rear axle. However, this structure is limited by the smaller number of teeth and offset size of the driving gear, and the driving gear has poor manufacturability. The main reduction ratio is only about 5, so it is mostly used in the through drive axle of light vehicles. When used in large vehicles, the total reduction ratio can be increased by adding wheel reducers or increasing the speed ratio of the transfer case. Worm gear worm type single-stage through-type main reducer can get a larger speed ratio when the structural quality is small. It is used for the layout of through drive axles of various tonnage multi-bridge drive vehicles. In addition, it also has the advantages of smooth and silent work, and is convenient for the overall layout of the car. For example, the worm-down layout scheme is used in the through drive axle of large buses, which can reduce the floor height of the carriage.
????For the medium and heavy-duty multi-axle-driven vehicles, because the main deceleration is relatively large, the two-stage through type main reducer is mostly used. According to the different combination of gears, it can be divided into bevel gear-cylindrical gear type and cylindrical gear-bevel gear type. Bevel gear-cylindrical gear type two-stage through-type main reducer can get a larger main reduction ratio, but the structure height is large, the driving bevel gear has poor manufacturability, the driven bevel gear adopts cantilever type support, the support rigidity is poor, and the disassembly is also inconvenient. The first-stage cylindrical gear pair of the cylindrical gear-bevel gear type double-stage through-type main reducer has the function of deceleration and penetration, and is sometimes only used as a through-general, and its speed ratio is designed to be 1. For example, the JHC1240 through bridge is composed of the rear axle, the middle bridge and the balanced suspension assembly. The key point of the through bridge is the middle bridge. The product has advanced performance, good reliability, good inheritance and strong bearing capacity. It is mainly used for 15 ~ 40 Tonnage trucks, modified vehicles, tractors and special vehicles. Dongfeng multi-axis off-road vehicles use through-type drive axles. Correspondingly, the main reducer also uses the through-type drive, such as the 6 × 6 off-road vehicle's through-type drive axle (middle axle) dual-stage main reducer. The first stage is helical cylindrical gear transmission, and its deceleration is relatively small. The driving cylindrical gear is splined on the through shaft, and the through shaft passes through the main reducer shell of the middle axle to the rear axle; the second stage is the hyperboloid bevel gear Drive, its deceleration is relatively large. There are also some through drive axles where the first stage is driven by bevel gears and the second stage is driven by cylindrical gears.