The full hydraulic steering system of wheel excavator is generally composed of hydraulic pump, steering wheel, steering gear, rotary joint, steering cylinder and oil tank pipeline.
The hydraulic pump supplies oil to the steering system. When the steering wheel does not rotate, the valve core inside the steering gear is in the middle position. The oil supplied by the hydraulic pump returns to the oil tank through the middle oil circuit of the valve core, and the steering hydraulic cylinder has no action.
When the steering wheel is turned, the steering column drives the valve core of the steering gear to rotate relative to the valve sleeve. The oil provided by the hydraulic pump drives the gear motor to rotate and then enters one side of the steering hydraulic cylinder through the rotary joint, while the oil circuit on the other side is connected with the oil tank to return oil, thus forming the steering action. The oil drives the gear motor to drive the linkage mechanism to make the valve sleeve rotate at the same time, forming a steering angle proportional to the steering wheel angle. When the steering wheel stops rotating, under the rotation of the gear motor rotor, the position of the valve core relative to the valve sleeve will be restored to the middle position, the oil circuit to the steering hydraulic cylinder will be cut off, and the steering action will stop.