1. In the middle position (when the steering wheel is not rotating). The oil from the oil pump is returned to the oil tank through the inside of the steering gear.
2. During power steering, the oil from the oil pump enters the cycloidal pin wheel meshing pair (metering motor) through the follow-up valve, pushing the rotor to follow the steering wheel, and depending on the steering angle of the steering wheel, the direction, and the quantitative pressure of the hydraulic oil into the cylinder The left cavity or the right cavity pushes the guide wheel to realize power steering. The oil on the other side of the oil cylinder is returned to the oil tank through the follower valve.
3. Manpower steering. When the engine is turned off, the steering wheel is operated by manpower, and the rotor of the metering motor is driven to rotate through the valve core, dial pin and linkage shaft in the steering gear. The metering motor presses the hydraulic oil into the cylinder and pushes the guide wheel to realize human steering. . The volume difference between the two chambers of the oil cylinder can be replenished from the oil tank through the oil return port. Since the steering gear is used for heavy vehicles with low speed, in order to prevent the steering wheel from being beaten up, the structure is designed as a happy and unresponsive structure. The external force acting on the steering wheel cannot be transmitted to the steering wheel, and the driver has no road feeling.