GPM2 Series

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GPM2FC004CK405 Hydraulic gear pumps

  • Description
  • Parameters and character
  • Our services
  • Inquiry


External gear pumps are the most popular pumps used in modern hydraulic systems.

Their features are versatility, strength and long useful life.

The simple construction ensures limited purchase costs and servicing. Thanks to there basic concepts, together with ever-improving product design and features, research-based on many years of experience, accuracy in material selection, producing process followed in great detail and tests on mass-produced parts, our gear pumps have reached top quality standards.

For this reason, our products can work under heavy operating conditions and transmit high hydraulic power. Furthermore,SJ-TECHNOLOGY gear pumps feature good hydraulic, mechanical and volumetric efficiency, low noise lever and, last but not least, compact dimensions.

SJ Technology gear pumps has further developed its own range of products with a new series of pumps named GPM where groups names 1P, 1A, GPM0.0, GPM1.0,  GPM2.0, GPM2.6, GPM3.0 are suitable for the most different applications in both industrial, mobile, marine and aerospace industries.

Generally these gear pumps, usually consist of a gear pair supported by two aluminum bushes, a body, a securing flange and a cover. Shaft of the driving gear projecting beyond the flange mounts a twin-lip seal ring (the inner lip being a seal and the outer being a dust seal). An elastic securing ring secures the ring in place. The body of the pump is made of special hi-resistant aluminum alloy obtained through extrusion process, while flange and cover are made out of spheroidal cast iron, this in order to ensure minimized deformation even when subject to high pressure, be it continuous or intermittent or peak pressure.

Gears are made of special steel. Their manufacturing process ground and fine finished so to have a high degree of surface ensure low pulsation levers and low noise levers during pump operation.

Bushings are made of special low-friction and hi-resistant aluminum alloy and manufactured from die-casting. Besides they are equipped with antifriction DU bearings.

Special compensation zones onto bushings, insulated by special preformed seals with anti-extrusion ring, allow fully free axial and radial movement to the bushes, which is proportional to pump operating pressure. In this way, internal dripping is dramatically reduced, thus ensuring very good pump performance (both in terms of volume and in general) and proper lubrication of pump moving parts.

Parameters and character

Our services


Before starting the system on a continuous basis, we suggest to adopt some simple precautions:

Check for the direction of rotation of the pump to be consistent with the drive shaft one.

Check for the proper alignment of pump shaft and motor shaft: it is necessary that the connection does not include axial or radial loads.

Protect drive shaft seal during pump painting. Check if contact area between seal ring and shaft is clean: dust could provoke quicker wear and leakage.

Remove all dirt, chips and all foreign bodies from flanges connecting inlet and delivery ports.

Ensure that intake and return pipes ends are always below fluid lever and as far from each other as possible.

Install the pump below head, if possible.

Fill the pump with fluid, and turn it by hand.

Disconnect pump drain during startup to bleed air off the circuit.

At first startup, set pressure limiting valves at min. value possible.

Avoid lower rotation speed than min. allowed with pressure higher than continuous max. pressure.

Do not start the system at low temperatures under load conditions or after long stops (always avoid or limit load starting for pump longer life).

Start the system for a few minutes and turn on all components; bleed air off the circuit to check its proper filling.

Check fluid lever in the tank after loading all components.

At last, gradually increase pressure, continuously check fluid and moving parts temperature, check rotation speed until you reach set operating values that shall be within the limits indicated in this catalogue.



Hydraulic Fluid  

Use specific mineral oil based hydraulic fluids having good anti-wear, anti-foaming, antioxidant, anti-corrosion and lubricating properties. Fluids should also comply with DIN51525 and VDMA 24317 standards and get through 11th stage of FZG test.

For the standard models, the temperature of the fluid should not be between -10℃ and +80℃。


Fluid kinematic viscosity ranges are the following:

Allowed Value

6÷500 cSt

Recommended value

10÷100 cSt

Value allowed at startup

2000 cSt


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