Excavator Hydraulic Pump Parts Piston shoe PSVL-54 Set of 9 pcs Spare Parts

Excavator Hydraulic Pump Parts Piston shoe PSVL-54 Set of 9 pcs Spare Parts

Axial Force Transfer & Automatic Angle Compensation
Within the cylinder block, pistons move linearly back and forth, while the swash plate is fixed at an inclined angle. Connected via spherical hinge, the piston shoe swings freely to match swash plate inclination and deliver piston axial thrust evenly to the swash plate. Once piston shoes are removed, point contact occurs between ball head and swash plate, leading to immediate crushing and heavy wear.

Adopt Surface Contact Instead of Point Contact to Lower Contact Stress
Piston ball heads adopt spherical shape, and piston shoes are manufactured with large flat bottom planes.
Ball head ↔ Piston shoe: flexible spherical hinge linkage
Piston shoe bottom ↔ Swash plate: surface sliding contact
Greatly expanded contact area reduces specific pressure to support stable long-term operation of high-pressure pumps.

Hydrostatic Oil Film Lubrication (Core Feature)
A small throttle opening sits at piston shoe centre. High-pressure oil flows through piston cavity, ball head and throttle opening into bottom concave area, forming a 10～30 μm thin high-pressure oil film between piston shoe and swash plate.
Advantages:
✅ Transform dry metal friction to fluid friction state
✅ Protect piston shoe and swash plate from scratch and burning caused by direct metal touch
✅ Dissipate frictional heat
Overflow oil enters pump housing and serves as internal leakage return medium.

Guarantee Surface Contact with Set Plate Preloading
Preload from set plate acts on piston shoe backs to make them stay tightly against swash plate. A full rotation of cylinder block enables each piston to finish one oil suction and one oil ejection cycle, and piston shoes conduct cyclic sliding movement on swash plate.

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