Gear Pump Series

Hydraulic gear pumps deliver reliable, cost-effective fluid power for a wide range of construction, agricultural, and industrial applications. Known for their simplicity, durability, and compact design, gear pumps are widely used as charge pumps, pilot pumps, and auxiliary hydraulic power sources in heavy equipment.

HE PUMP stocks a comprehensive range of gear pumps compatible with Caterpillar, Komatsu, Volvo, JCB, Hitachi, John Deere, Kubota, Sany, XCMG, and other major equipment brands. Each pump is manufactured as a direct-fit OEM-compatible replacement.

What Does a Gear Pump Do?

A gear pump moves hydraulic fluid by trapping it between rotating gear teeth and the pump housing, then forcing it out under pressure. There are two main types:

  • External gear pumps: Two matching gears mesh and rotate — one driven by the shaft, the other idling. Simple, efficient, and handles high pressure well.
  • Internal gear pumps: An inner gear rotates inside an outer ring gear with a crescent-shaped spacer. Better at handling high-viscosity fluids and low-speed operation.

Common Applications in Heavy Equipment

  • Charge Pumps: Supplying make-up oil to main piston pump circuits in excavators and loaders to prevent cavitation
  • Pilot Pumps: Providing hydraulic control pressure for spool valve operation and joystick controls
  • Fan Drive Pumps: Powering engine cooling fan motors on wheel loaders and dozers
  • Steering Pumps: Delivering hydraulic pressure for articulated steering systems
  • Power Take-Off (PTO): Agricultural and truck-mounted hydraulic systems for implements and body lifts
  • Auxiliary Systems: Powering secondary functions such as implement hydraulics, winches, and tool circuits

Why Choose Gear Pumps?

  • Lower Cost: Gear pumps cost significantly less than piston pumps for comparable flow rates
  • Compact Design: Small footprint allows installation in tight engine compartments
  • Contaminated Fluid Tolerance: Gear pumps handle dirty or abrasive fluid better than piston or vane pumps
  • Simple Maintenance: Few moving parts means fewer failure points and easier troubleshooting
  • Reversible Flow: External gear pumps can often be reversed by changing rotation direction

Equipment We Cover

  • Caterpillar Excavators: 320, 325, 330, 345, 374 series
  • Caterpillar Wheel Loaders: 950, 966, 980, 988 series
  • Caterpillar Motor Graders: 12M, 14M, 16M, 18M series
  • Caterpillar Bulldozers: D6, D8, D10, D11 series
  • Other Brands: Komatsu, Volvo, JCB, Hitachi, John Deere, Kubota, Sany, XCMG

Signs of Gear Pump Failure

  • Reduced hydraulic flow or pressure at attachments
  • Whining or growling noise from the pump area
  • Overheating hydraulic fluid (gear pumps are less efficient at high pressure)
  • External fluid leaks at pump seals or housing
  • Slow or weak auxiliary hydraulic functions

Preventing Gear Pump Failure

  • Replace hydraulic filters on schedule: Contaminated fluid accelerates gear and bearing wear
  • Avoid prolonged high-pressure operation: Gear pumps are best suited for medium-pressure applications; excessive pressure causes case rupture
  • Check rotation direction: External gear pumps are directional — installing them backwards will not produce flow
  • Monitor case drain pressure: Excessive case pressure can blow seals and damage bearings
  • Use the correct hydraulic fluid: High-viscosity fluid at low temperatures increases pump load and shortens life

If your equipment shows signs of reduced hydraulic flow or unusual pump noise, test the gear pump output pressure first. Low pressure with the system warm usually indicates internal gear wear or a failed case drain.

Browse our full range of CAT hydraulic gear pumps — or contact us with your model and serial number for the correct part.

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