Hydraulic Gear Pump Guides and Reviews

The hydraulic gear pump article provides guidance and review about different types, qualities, durabilities, and prices. The fluid is transferred by the mechanical action of the gears. Hydraulic gear pumps convert mechanical power into the hydraulic energy of the fluid.

The rotation of the gear causes the suction at the inlet and fluid is transferred by the pump. The fluid flows over the gears. The mechanical energy by the rotation of gears is transferred into the fluid pressure at the discharge. The separation of both the gears at the inlet causes a vacuum. The vacuum leads to the suction in the pump. The gear rotation performs two functions here namely as

  • Creates a suction pressure at inlet leading to the flow of fluids and
  • Forcing the liquid outside the discharge side.

Gear pumps are positive displacement type pumps. They transfer only a fixed amount of the fluid for each rotation. Gear pumps can transfer highly viscous fluids. The hydraulic gear pumps can be external gear type, internal gear type, or gerator type.

Mostly, spur gears are used in the pumps. The bevel gears, screw gears, helical gears can also be used. These pumps can produce fluid discharge at a high-pressure range due to the tight tolerances. 

Hydraulic Gear Pump Selection

Hydraulic gear pump

Hydraulic gear pump must be selected considering the various physical and environmental conditions affecting the pump as follows:

Type of pump – We must decide the type of pump required for our applications such as internal gear pump or external gear pump. External gears are most suitable for high-pressure and high-flow applications. Internal gear pumps are used in low-flow and precision flow applications. 

Displacement or flow rate –the amount of fluid to be transferred by the pump. The fluid is transferred through the clearances between the mating gears. The tight clearances between the gears are required for the effective displacement of the fluid. The flow rate is expressed in terms of volume per unit time and measured in gallons per minute (GPM).

Viscosity – resistance to the flow. The viscosity of the fluid plays a vital role flow of the fluid. The fluids occupy the clearances between the gear and casing and are transferred. Low viscous fluids can be carried easily but high viscous fluids need time to fill in the clearances. The speed of the fluid must be lowered. The speed of the gears decreases with increase in the fluid`s viscosity.

Power – amount of energy required to move the fluid effectively in the required flow rate. Power is given to motor which is coupled to the gears. The rotation of gears leads to the transfers of the fluid. Power is usually rated in terms of Horse power (HP).


Hydraulic gear pump
  • Ability to operate at high pressure and temperature conditions.
  • Relatively quiet operation
  • Great flow control and can be used for metering applications
  • Multi-fluid compatibility so can be used in the blending and mixing applications.
  • Devoid of the cavitation problems.
  • Highly reliable.
  • Ability to handle corrosive liquids.


  • Solid wastes are not allowed due to the low clearances between the gears and casing. The solid particles may cause wear of the gears 
  • Fixed flow rate.
  • Precise machining of gears is required.
  • Effective coolants such as the oil must be provided for lubrication in the gears. Lubricants may contaminate the transfer fluid.

Brands and Prices

Hydraulic gear pumps are used in a wide range of applications for industrial, residential and domestic purposes. Hydraulic gear pumps are manufactured mainly by some of the leading companies in markets such as Ampco Pumps, Eaton Pumps, Parker Pumps, Houston Hydraulics, Witte Pumps & Technology, etc. Their prices vary from 250$ in low flow pumps to 2000$ to 4000$ for large capacity pumps.

Parker Pumps is one of the leading company in the gear pump market. Their pumps are used in construction, agricultural, industrial, material handling, and forestry applications. They have research and development team to produce customized pumps for special requirement.

Witte Pumps and Technology concentrate mainly on providing customized pumps for the unique customer needs. They also have a standard set of pumps for commercial purposes. They also manufacture parts and accessories for the pumps. Their pumps are used in the chemical industries, booster pumps, metering applications and low-pressure industrial applications.

Houston Hydraulic designs and manufactures hydraulic equipment and hydraulic power units. They provide pumps along with the motors and sell as pump-motor combos. The pump-motor combos are customized as per the customer requirement for the effective functioning.

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