Automobile steering systems are divided into two categories: mechanical steering systems and power steering systems.
The mechanical steering system uses the driver's physical strength as the steering energy source, and all the power transmission parts are mechanical. The mechanical steering system is composed of three parts: steering control mechanism, steering gear and steering transmission mechanism.
When the car turns, the driver applies a steering torque to the steering wheel 1. The torque is input to the steering gear 5 through the steering shaft 2, the steering universal joint 3 and the steering transmission shaft 4. The torque amplified by the steering gear and the decelerated motion are transmitted to the steering rocker arm 6, and then transmitted to the steering knuckle arm 8 fixed on the left steering knuckle 9 through the steering straight rod 7, so that the left steering knuckle and the left knuckle supported by it are transmitted The steering wheel deflects. In order to make the right steering knuckle 13 and the right steering wheel supported by it deflect correspondingly, a steering trapezoid is also provided. The steering trapezoid is composed of trapezoidal arms 10 and 12 fixed on the left and right steering knuckles and steering tie rods 11 whose ends are connected with the trapezoidal arms as ball hinges.
A series of components and parts from the steering wheel to the steering drive shaft belong to the steering mechanism. The series of components and parts (excluding the steering knuckle) from the steering rocker arm to the steering trapezoid all belong to the steering transmission mechanism.
The power steering system is a steering system that uses both the driver's physical strength and engine power as the steering energy. Under normal circumstances, only a small part of the energy required for vehicle steering is provided by the driver, and most of it is provided by the engine through the power steering device. However, when the power steering device fails, the driver should generally be able to independently assume the steering task of the vehicle. Therefore, the power steering system is formed by adding a power steering device to the mechanical steering system.
For heavy-duty vehicles with a maximum total mass of more than 50t, once the power steering device fails, the force applied by the driver to the steering knuckle through the mechanical transmission system is far insufficient to deflect the steering wheel to achieve steering. Therefore, the power steering device of this kind of automobile should be particularly reliable.