Excavator parts AP2D25 VOE 14520404 Piston Shoe Set Of 10 Pc For Hydraulic Pump Parts

Excavator parts AP2D25 VOE 14520404  Piston Shoe Set Of 10 Pc For Hydraulic Pump Parts

Force Transmission and Angle Self-Adaptation
Inside the cylinder block, the piston moves back and forth linearly, whereas the swash plate is fixed at an inclined angle. Connected by a spherical hinge, the piston shoe can swing freely matching the swash plate’s inclination and steadily transmit the piston’s axial thrust to the swash plate. Removing the piston shoe would let the piston ball head bear directly against the swash plate via point contact, which leads to immediate crushing and heavy abrasion.

Convert Point Contact into Surface Contact for Lower Contact Stress
The piston ball head adopts spherical structure, and the bottom face of the piston shoe is broad and flat.
Ball head ↔ Piston shoe: flexible spherical hinge connection
Piston shoe base ↔ Swash plate: sliding with surface contact
The contact area expands greatly to cut down unit pressure, satisfying continuous service demands of high-pressure hydraulic pumps.

Hydrostatic Oil Film Lubrication (Core Function)
A small orifice sits at the piston shoe’s centre. High-pressure oil passes through the piston cavity, ball head and orifice into the bottom recess of the piston shoe, generating a 10～30 μm thin high-pressure oil film between the piston shoe and swash plate.
Advantages:
✅ Replace metal dry friction with fluid friction
✅ Avoid scuffing and seizure of piston shoe and swash plate from direct metallic contact
✅ Dissipate friction heat
Excess oil flows into the pump housing and acts as internal leakage return oil.

Keep Tight Contact with Support from Set Plate
The set plate pushes against the rear side of each piston shoe to maintain constant attachment to the swash plate surface. When the cylinder block rotates one full circle, every piston completes one suction and one delivery cycle, and the piston shoe slides repeatedly along the swash plate.

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