1A Series

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Hydraulic Gear Pumps G2

  • Description
  • Parameters and character
  • Our services
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The gear pumps are designed for transforming the mechanical energy as energy of the working liquid (pressure and flow rate). They are simplified in construction and they have a relatively low cost. All these benefits ensure their wide application in the hydraulic systems.

Drive arangements :The pump drive may be direct or indirect (by gear, chains, or belt transmissions). Both drives should not impose axial or radial forces on the pump shaft. Oldham coupling serrated drive adapters are used with direct drive. For indirect drive refer to the manufacturer.

The gear pumps are designed to work at the conditions mentioned below:

- Working liquid: hydraulic oils with viscosity 16 ... 200mm2/s;

- Degree of filtration:  15 ... 25ìm;

- Ambient temperature range: - 22 ... 55 °C;

- Fluid temperature range: - 25  ...  80   °C;

- Inlet pressure, absolute:    0.8 ... 2.2 bar;

- Fluid velocity (suctiun line) 0,5 ... 1m/s

- Outlet pressure up to 250bar.


The gear pumps made by “SJ TECHNOLOGY” are produced in 5 different groups: 00, 10, 20 and 20H, 30 and 40. The displacements  of the pumps are in the range  from  0.25 to 60 cm3.

Group 00 q = 0.25 ...2 cm3;

Group 10 q = 1 ... 9.8 cm3;

Group 20 q = 4.5 ... 25 cm3;

Group 20H q = 15 ... 36 cm3;

Group 30 q = 20 ... 60 cm3;

Group 40 q = 46 ... 60 cm3.


There are different variants of flanges, shafts and ports for each pump group (standard; Germany; USA ...).

Parameters and character

Our services


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

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

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

l 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.

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

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

l Install the pump below head, if possible.

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

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

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

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

l 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).

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

l Check fluid lever in the tank after loading all components.

l 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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