The Pilot Pump is the control oil source of the excavator hydraulic system,and the vast majority of them are external gear pumps.It is generally installed at the rear end of the main Hydraulic Pump,driven coaxially by the main pump,and specifically provides low-pressure control oil,which is equivalent to the"control power supply"of the hydraulic system.It does not directly drive the oil cylinder or motor.The low-pressure oil output is supplied to the operating handle,foot valve,and safety lock solenoid valve,which drives the main control valve spool to change direction.Only then can the high-pressure oil from the main pump flow to the executing components such as the boom,forearm,rotation,and walking to complete the action.

　　The structure of the pilot pump mainly includes the pump housing,driving gear,driven gear,front and rear cover plates,skeleton oil seal,and some pumps integrate pilot relief valves.During operation,gear meshing causes a change in volume,which draws oil from the hydraulic oil tank and pressurizes the output pilot pressure.The normal working pressure is generally 30-45 bar,and the maximum pressure is limited by the pilot relief valve.Excess oil overflows back into the oil tank.

　　Whole machine oil circuit process:Pilot pump oil suction→Output pressure oil→Pilot Filter element→Safety lock solenoid valve→Operating handle foot valve→Main control valve core.The gear and cover plate are lubricated by hydraulic oil.High frequency operation conditions in mines,continuous high-speed operation of pumps;Hydraulic oil pollution and metal impurities can easily wear down gears and cover plates,causing internal leakage and pressure drop.

　　Pilot pump failure will not report a fault code.Typical symptoms include slow vehicle movement,heavy handle operation,further deterioration of hot vehicle movement,and severe vehicle inactivity;Partially accompanied by abnormal noise from the pump body and oil leakage due to oil seal damage.Many repairs encounter slow movements and directly suspect the main pump,ignoring the pilot pump,resulting in misjudgment.The pilot pump belongs to the low-pressure gear pump,and the accessory price is not high,but once it fails,the whole machine cannot work.Familiar with the principle of the pilot pump,pay attention to the cleaning of the pilot filter element and hydraulic oil,which can effectively avoid premature damage to the pilot pump and ensure the sensitive and reliable operation of the whole machine.