The valve is composed of return spring 2, slide valve 4, valve body 3, etc. The structure is shown in Figure 2-13. The travel shuttle valve is installed on top of the four-way reversing valve and is controlled by the left travel oil circuit. When the walking and working device (or swing) are simultaneously operated, the pressure oil from the shuttle valve of the piloting valve (PPC valve) of the working device (or swing) flows to the straight travel valve through the walking prism valve. Its working principle is shown in Figure 2-14.
(1) Only operate the walking joystick. When the walking joystick is in the "forward" position, the control pressure oil from the left walking forward circuit flows to port P1 and pushes the spool to the right. Therefore, the PB, P., and Po ports pass through the The grooves are all connected and all communicate with the linear travel valve. Since no pilot pressure oil flows from the shuttle valve of the PPC valve, the linear travel valve does not work.
When the walking joystick is in the "backward" position, the pressure oil is controlled to flow from the left to the backward oil passage to the P, port, and the spool is pushed to the left. P, mouth, P: mouth, Ps mouth and P.
The ports are all connected through the grooves on the spool valve and are all connected to the linear travel valve. Because there is no pilot pressure oil from the pilot control valve (PPC valve), the linear travel valve does not work.
(2) Simultaneously control walking and working (or slewing) devices. Make the walking joystick in the "advance" position, and simultaneously operate the stick joystick to control the pressure oil to flow from the left to the forward oil path to the P, port, and push the slide valve to the right, the shuttle valve pilot pressure oil from the stick PPC valve Flow to the PB port, and then to the P through the groove on the slide valve. Port, and then flow straight to the valve.
When the boom (or bucket) and the walking device are operated at the same time, as above, the shuttle valve pilot pressure oil from the PPC valve of the arm (or bucket) flows to P, port → Pa port → P. Port → linear travel valve.
When operating the excavator slewing and walking devices at the same time, the pilot pressure oil from the shuttle valve of the slewing PPC valve flows to P; port → Pa port.
