1. The axle (also known as axle) is connected with the frame (or load-bearing body) through the suspension. The wheels are installed at both ends of the axle. Its function is to transmit the forces and moments in all directions between the frame (or load-bearing body) and the wheels.

根据悬架结构的不同，车桥分为整体式和断开式两种。当采用非独立悬架时，车桥中部是刚性的实心或空心梁，这种车桥即为整体式；断开时车桥一般为铰链连接的结构，与独立悬架配用。

According to the different suspension structure, the axle is divided into integral type and disconnected type. When the independent suspension is adopted, the middle part of the axle is a rigid solid or hollow beam, which is an integral type; when the suspension is disconnected, the axle is generally a hinged structure, which is used with the independent suspension.

根据车桥的功能，车桥又可分为转向桥，驱动桥，转向驱动桥和支持桥四中类型。其中，转向桥和支持桥都属于从动桥。一般汽车多以前桥为转向桥，而以后桥或中、后桥两桥为驱动桥。越野车的前桥则为转向驱动桥。三轴汽车前桥为转向桥，中、

According to the function of the axle, the axle can be divided into four types: steering axle, drive axle, steering drive axle and support axle. Among them, the steering axle and the support axle belong to the driven axle. Generally speaking, the front axle is the steering axle, while the rear axle or the two axles of the middle and rear axles are the driving axles. The front axle of the off-road vehicle is the steering drive axle. The front axle of the three axle automobile is the steering axle

后桥其中一个或两个都为驱动桥，即为6*2或6*4驱动形式的汽车。

One or both of the rear axles are drive axles, i.e. 6 * 2 or 6 * 4 drive vehicles.

2.转向桥

2. Steering axle

a.转向桥的功用与组成 转向桥能使装在前端的左、右车轮偏转一定的角度来实现转向，还应该能承受垂直载荷和由道路、制动等产生的纵向力和侧向力以及这些力所形成的力矩。因此，转向桥须有足够的强度和刚度；车轮转向过程中相对运动的部件之间摩擦力应该尽可能小；保证车轮正确的安装定位，从而保证汽车转向轻便和方向的稳定性。

a. The function and composition of the steering axle can make the left and right wheels installed in the front end deflect a certain angle to realize the steering, and it should also be able to bear the vertical load, the longitudinal and lateral forces generated by the road, braking, etc., as well as the moment formed by these forces. Therefore, the steering axle must have enough strength and rigidity; the friction between the relative moving parts in the process of wheel steering should be as small as possible; to ensure the correct installation and positioning of the wheel, so as to ensure the vehicle steering light and direction stability.

b.转向车轮定位  转向桥在保证汽车转动功能的同时，应使转向轮有自动回正的作用，以保证汽车直线行驶的稳定性。当转向轮偶遇外力作用发生偏移时，一旦外力消失能立即自动回到直线行驶状态。这种自动回正作用是由转向轮的定位参数来实现的，就是汽车的没个转向轮、转向节和前轴与车架的安装应保持一定的相对位置。车轮定位参数包括主销后倾，主销内倾，前轮外倾和前轮前束四个参数。通常车轮定位是指前轮定位，现在也有许多车辆需要除前轮定位外的后轮定位，及四轮定位。

b. Steering wheel positioning the steering axle should make the steering wheel have the function of automatic return while ensuring the turning function of the car, so as to ensure the stability of the straight-line driving of the car. When the steering wheel is displaced by the external force, it will automatically return to the straight driving state once the external force disappears. This automatic return function is realized by the positioning parameters of the steering wheel, that is, the installation of the steering wheel, the knuckle and the front axle of the car and the frame should maintain a certain relative position. Wheel alignment parameters include kingpin caster, kingpin inclination, front wheel camber and front wheel toe in. Usually, wheel alignment refers to front wheel alignment. Now there are many vehicles that need rear wheel alignment and four-wheel alignment besides front wheel alignment.