The excavator swing priority valve is beside the spool of the five-way reversing valve. When the swing device and the stick are operated at the same time, most of the pressure oil flows to the stick with a smaller load, and the flow to the swing oil path is reduced, so the speed of the stick is faster than the speed of the swing, which makes the joint operation difficult . The role of the rotary priority valve is to limit the pressure oil flow to the stick-low speed control valve during the joint operation, which limits the speed of the stick and improves the joint operation performance.
(1) When the rotary joystick is in the neutral position, there is no pilot pressure oil from the shuttle valve, and the rotary priority valve does not work. At this time, the pressure oil output from the front main pump flows through the Pa port and all flows to the stick-low speed control valve.
(2) When operating the swing device. The pilot pressure oil from the shuttle valve pushes the spool of the rotary priority valve to the left. Therefore, the pressure oil from the front main pump flows through the Pa port to the stick-low speed control valve and is throttled, and the stick speed is controlled. Improved joint operation performance.
