Excavator Pump Parts AP2D21 Spare Part For Hydraulic Pump

Excavator Pump Parts AP2D21 Spare Part For Hydraulic Pump

When the pump rotates at high speed, the retainer plate pushes all piston shoes backward continuously. As a thrust washer, the shoe plate bears the axial force from the retainer plate, separates the retainer plate from the pump housing and prevents direct wear of the housing.

It forms a sliding friction pair and builds up oil film lubrication. A hydrostatic lubricating oil film is formed on both surfaces to reduce rotational friction of the retainer plate. Meanwhile, the oil film provides buffering and shock absorption to absorb impacts generated by high‑speed rotation.

It controls the axial clearance and defines the assembly clearance between the retainer plate and swash plate. Abnormal clearance will lead to problems: poor contact between piston shoes and swash plate, increased internal leakage, insufficient pump flow and abnormal noise.

It protects the pump housing. With higher hardness than the housing, wear occurs preferentially on the shoe plate. Only replacing this steel plate can avoid scuffing damage to the pump housing.

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