OEM REXROTH Hydraulic Pump AP2D25 Hydraulic Pump Excavator Hydraulic Parts Hydraulic Pump Parts

REXROTH Hydraulic Pump AP2D25 Excavator Hydraulic Parts Hydraulic Pump Parts

Core Function

Powered by the engine, the hydraulic pump spins and transforms the engine’s mechanical energy into pressure energy within hydraulic oil. High‑pressure hydraulic oil is fed into every hydraulic cylinder and motor, enabling boom lifting, arm extension and retraction, bucket opening and closing, machine travel, and upper‑body rotation. The excavator cannot operate at all without a hydraulic pump.The engine spins the hydraulic pump’s internal components rapidly, sucking in hydraulic oil and pressurizing it.

Pressurized oil travels through pipelines to cylinders and motors to drive boom, arm, bucket, travel and slew movements. Once controls are released, oil returns to the hydraulic tank to finish the circulation process.Power Input:Through a coupling, the excavator engine rotates the hydraulic pump’s main shaft and cylinder block (piston‑type cylinder block) at high speed.

Oil Suction (Low‑Pressure)Several pistons fitted inside the cylinder block rotate together with it. Guided by the swash plate, pistons move back and forth. As pistons retract, the pump’s internal volume expands, generating negative pressure to pull hydraulic oil from the tank.Oil Discharge (High‑Pressure)When pistons stretch out, internal volume shrinks and oil is compressed into high‑pressure fluid. This high‑pressure oil flows through the valve plate and outlet to the main control valve (distribution valve).

Automatic Flow Adjustment (Variable Displacement, Core Function)

When facing heavy loads such as digging soil or hoisting heavy materials, the pump raises its displacement and flow automatically for greater power. During no‑load or light‑load operation, it cuts displacement to conserve fuel. This process relies on internal servo valves and regulators adjusting swash plate angles to alter piston stroke lengths.

 

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