Latest News

View More

Gear Pumps

Introduction of GRH Gear Pump

Gear pumps from GRH Hydraulic have a floating bushing feature with automatic axial clearance compensation. The bushings are made with special abrasion resistant material providing improved service life. Precisely machined gears ensure our units provide excellent low noise characteristics. Our cold extrusionmotor bodies can endure pressures above 30Mpa. High strength cast iron front & rear covers also enhance our reliability. Our units are widely used in the industrial, mobile, marine and aerospace industries.

GRH Gear Pump Characteristics

GRH gear pumps are produced in 7 different versions (0P, 1P, 1.5P, 2P, 2.5P, 3P, 3.5P) and in each group different displacements are obtained by changing the gears width.

Pressure: GRH offers two pressure ratings, F and G, pleas refer to charts:

Efficiencies: volumetric up to 98%, mechanical up to 93%.

Mountings: flanges, shaft ends and ports.

Seals: Viton seals available.

Integrate: all pumps can be ordered with relief valve and check valve.


To achieve the performance it necessary not only to meet the catalogue but also to take real care of the design of the hydraulic as a whole, in particular:

The design of the hydraulic circle, especially the suction line, dimension and position of the valves, the filters the reservoirs and the heat exchanger.

Ensure correct and frequent cleaning and maintenance of the circle and of the hydraulic fluid.

Equip the circuit with suitable alarm and safety devices.

Avoid possible starting under load at lower temperature.

Avoid high pressure at low speed.

In reason choice oil is major factor.

Hydraulic Fluid

Fluid must be specifically for hydraulic equipment, it must be nonfoaming, antioxidant, noncorrosive and have good lubricating features meeting the following requirements:

Recommended useGB11118-94L-HM46 or equate NFE-603/DIN51524Ⅱ-85

Minimum Rotational Speed

We recommend a minmum rotational speed for every pump group as follows:





Hydraulic Circuit

Avoid shard restrictions and small radius bends.

Place safety relief valve set at correct pressure and with good dynamic characteristic.

Recommended fluid speed in the inlet line1.65ft/s(0.51.5m/s).

Recommended fluid speed in the delivery line6.520ft/s(26m/s).

Recommended fluid speed in the return line510ft/s(1.53m/s).

Reservoir should have a capacity about twice as much as the volume of delivered by the pump in one minute.

The return and inlet pipe must be separated as far as possible and under the minmum level of the oil.

Install pump in a well cleaned environment and make sure prior starting the system that all pipe and reservoir are perfectly clean. It is recommended to filter the new oil at 8-10um befor filling the reservoir.

Fill the pump with fluid befo installing and check the direction of rotation.

For the first run of the pump it is advisable to disconnection the pump diacharge in order to purge the air from the system.

GRH Gear Pump Character

By far largest number of premature failures of gear pumps are due to contamination; filtering with clogging indicating and alarms is recommended.

The initial contamination of the fluid must not exceed class 10 NAS 1638. Pass experience has shown that even brand new fluid often exceed this value. In this case it is recommended below 60μm inlet side, and in the return side.

Driving arrangements

The pump must be in line with the P.T.O.

Do not apply radial or axial loads on the pump shafts, the use of three coubling is recommended.

Make sure that the absorbed torque does not exceed the max. Torque allowed for the shaft.

Belt and gear drive not recommended because they affect the pump performance and life.

Calculated Formula

General Notes

Deliveries are carried out under the conditions of shanghaiguorui .

This catalogue is issued to provide outline information only. We reserve the right to change without any notice the design, features.

Please contact us if you have special request.

For detailed information, pls point and click