How the pilot pump work



The excavator pilot pump pushes the main control valve block stem (distribution valve) through the pilot ppc valve (handle, foot valve), and sends the high-pressure oil output from the main pump to the designated working device, such as the boom, forearm, shovel Bucket, swing motor, walking motor.



On the other hand, the pilot pump provides low-pressure oil for the control system, including handles, foot pedals, and some other equipment attached to the control valve (such as the control circuit of the breaker, hydraulic clamp).

In the electronic control state, the pilot secondary oil flow independently controls the secondary piston. The negative flow does not participate in the direct control. Instead, the negative pressure sensor collects its pressure parameter and provides it to the computer. The computer calculates it as a control of the electric proportional valve current. Parameters to control the pilot secondary oil flow.



In the hydraulic control state, the pilot secondary oil flow is cut off by the liquid-to-electric control valve and does not participate in the control of the secondary piston. The secondary piston is directly controlled by the negative flow. The working direction of the secondary piston is to push the spool of the spool to the left, which is balanced by its own spring return. https://www.dtsanyparts.com/slew...ot-valve-for-sy215c.html