Hydraulic gear pump component Bushing Block

Hydraulic component Bushing Block

In a hydraulic gear pump, the Bushing Block (more commonly and accurately called a Wear Plate or Pressure Plate) is a critical component that serves as the sliding bearing surface for the gears and, most importantly, contains the high-pressure and low-pressure zones. Its primary functions are to seal the sides of the gears to prevent internal leakage and to support the axial loads generated by the system pressure.

A gear pump bushing block (wear plate) has three core functions:

• Axial Sealing: It provides a precision flat surface for the sides of the gears to run against. This creates a seal that prevents high-pressure oil from the outlet side from leaking back to the low-pressure inlet side across the faces of the gears. This is the most common path for internal leakage in a gear pump.

• Axial Load Support: System pressure acts on the wear plates, pushing them against the gears. The plates must withstand this force to maintain the critical sealing gap.

• Bearing Surface: It acts as a hydrodynamic bearing for the gear shafts. Oil films between the gear faces and the wear plate surface prevent metal-to-metal contact, reducing wear.

2. Key Components and Design
A typical gear pump has two identical bushing blocks/wear plates, one on each side of the gear set.

• Body: A precisely machined, flat plate, usually made of a bearing-grade material like bronze, copper-alloy, or a specialized steel.

• Bore Holes: The plates have holes that align with the pump’s casing to allow for the passage of oil.

• Pressure Actuation Area: A critical design feature. The back of the wear plate is exposed to system pressure (often via a small passage from the outlet port). This hydraulic pressure pushes the wear plate firmly against the side of the gears, creating a pressure-balanced or pressure-compensated seal. The sealing force increases automatically as system pressure increases.

• Grooves and Passages: Some designs have grooves to help distribute lubrication and pressure evenly across the face.

Mechanical properties