Excavator parts Doosan 130 DH140 wheel excavator gear pump hydraulic tail pump pilot pump loader gear pump 31LB-40500 brake pump engineering machinery parts 31QB-30130 R520-9 R480-9

307002-4472 ZEXEL GEAR PUMP 9217996

307012-1100, 307012-1021 ZEXEL GEAR PUMP 9218028, 9621810752, 74918H
307012-1091, 307012-1090 ZEXEL GEAR PUMP 9218029 Kubota KH60, KH66, KX71
0510565058, 94126A 68741 61110 94508S
307012-8140 ZEXEL 94123Z
307012-3000 ZEXEL
307012-8020 ZEXEL 12+12+7.5 cc/rev
307002-3480 ZEXEL GEAR PUMP 9217990, 74409A, 68761-61170
307001-3420 ZEXEL Hitachi GEAR PUMP 9217979
307012-1090 ZEXEL GEAR PUMP 9218035 Kubota KH60, KH66, KX71
307012-8200 ZEXEL GEAR PUMP 9218043 KUBOTA KH60, KX41
0510365013, 307012-8201, 9218043, 38730, 3070128201, AZPFFF-11-005/005/004RXB202020MB, 222P5/5/4/4XB365013C

307002-4671 ZEXEL GEAR PUMP 9218006, 66415 88209, RD30161120
307002-4210 ZEXEL GEAR PUMP Hitachi 9217993
307002-5540 ZEXEL GEAR PUMP 9218012
307012-1311 ZEXEL GEAR PUMP 9226347, 74708H

The working principle of the hydraulic pilot pump is based on "volume change suction and discharge of oil". The core is to generate a volume difference through the rotational movement of the mechanical structure to provide stable low-pressure oil for the pilot control system (such as the control chamber of the pilot relief valve and the reversing valve). The specific process is as follows:

1. Oil suction process:
The power source (such as a motor, an engine) drives the rotor (gear, blade or plunger) in the pump to rotate, and the volume of the closed cavity formed by the rotor, the pump body and the end cover gradually increases, and the pressure in the cavity decreases to form a vacuum. At this time, the oil in the oil tank is sucked into the cavity through the oil inlet under the action of atmospheric pressure.
2. Oil discharge process:
As the rotor continues to rotate, the volume of the closed cavity gradually decreases, the oil in the cavity is squeezed, and the pressure increases. When the pressure exceeds the required pressure of the pilot control system (usually low, 2-30MPa), the oil is squeezed out through the oil outlet and transported to the pilot oil circuit to provide power for various control components.
3. Pressure stabilization assistance: Some pilot pumps are equipped with a small overflow valve or pressure compensation device. When the pilot oil circuit pressure is too high, the excess oil flows back to the oil tank to ensure that the output pressure is stable within the set range and avoid overloading the pilot element.

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31QB-30130 Excavator parts Doosan 130 DH140 wheel excavator gear pump hydraulic tail pump pilot pump Images