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Why CB Series Gear Pumps Are Limited to Low-Pressure Systems

2025-12-23

What are CB series gear pumps and what are their structural features?

CB series gear pumps are external gear pumps widely used in basic hydraulic systems.

They are valued for simple structure, low cost, and stable flow, making them ideal for low-pressure applications.

CB gear pumps typically feature:

Plain bearings (sliding bearings)

Fixed displacement design

Larger internal clearances

No axial or radial pressure compensation

These characteristics directly influence their pressure capability.

Why CB Series Gear Pumps Are Limited to Low-Pressure Systems

1. Reason #1: Limited Bearing Load Capacity

CB pumps usually use sliding bearings, which have limited load-bearing capacity.

At high pressure, radial forces on the gear shafts increase significantly, accelerating bearing wear and leading to early failure.

2. Reason #2: Lack of Pressure Compensation

CB gear pumps do not include axial or radial compensation mechanisms.

As pressure rises, internal clearances cannot be automatically adjusted, resulting in rapid efficiency loss and wear.

3. Reason #3: Large Internal Leakage at High Pressure

Higher system pressure increases internal leakage through:

Gear side clearances

Gear tooth meshing gaps

This causes:

Reduced volumetric efficiency

Increased heat generation

Unstable system performance

4. Reason #4: Housing Strength Limitations

The pump housing of CB series pumps is designed for low to medium pressure levels.

Operating beyond rated pressure may cause:

Deformation of the pump body

Increased noise and vibration

Risk of structural damage

Typical Applications of CB Gear Pumps

CB series gear pumps are commonly used in:

Agricultural machinery

Small hydraulic power units

Low-pressure lifting systems

Simple industrial equipment

Recommended working pressure: typically ≤ 16 MPa (depending on model).

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