Iran Tolid Industrial Group, Gear Pump and Gear box Production

Introduction of Gear Pumps

Gear pumps have been developed to pump and transfer liquids with a high volume weight and low pressure (below eight bars). The pumped liquid shall has the auto-lubricating characteristic, and be free of any solid corrosive, frictional and impure materials.


The rotating gear pumps are designed to pump the lubricating system, gas-oil fuel, molasses, paste and other auto-lubricating liquids used variously in industry. It is recommended these pumps to be used for the lubrication of cooling system of different machines (machine tools, combustion engines, etc.) with low pressure.


Tow (drive and driven) gearwheel rotates in the housing of pump. During rotation, the gears keep the liquid existing in suction port between pump housing and gear crown and transfer the liquid to the discharge box of the pump. Then, the gears push the liquid with pressure towards discharge port. The drive shaft is located over the driven shaft and the coupling key can be placed on the drive shaft.

In both sides of the shafts, there are supporting bushings lubricated using pumped liquid. The supporting bushings and thread packing (graphic thread) prevents the pumped to lead from the sides of the drive shaft.

(For pumping liquids, having the temperature of 80 to 300 ºC, special pumps developed for high temperature shall be used).

Safety Equipments

In some models, a special relief value is installed on the pump housing. If the working pressure exceeds the permissible amount, this valve will be opened and the pumped liquid can be transferred through internal channel to the suction box of the pump.

Pump Rotor

Gear pumps are designed for direct couple with electromotor installed on a frame, and low speed (below 700 R.P.M) or it is connected through an electromotor and reduction gearbox installed between electromotor and pump.

The drive shaft is rotated only using torque arm, and the value of the primary radial torque and engine torque of the first stroke has been determined.

Direction of Pump Rotation

Most of the gear pumps rotate clockwise (from the side of drive shaft). For the equipments designed for the pumps rotating in the left direction, the system is designed for the opposite direction.

Materials used in Pumps

Standard pumps are manufactured using cast iron housing, electroplated steel gear and a steel shaft.

The bushings of these pumps are made of cast iron covered by brass. Moreover, steel bushings covered with brass under centrifugal casting are used.


General Principles

In general, pump shall work with lower speed when materials with higher density (heavy materials) or liquids with lower lubricating property are used. A Pump with low-speed rotation is used when it is planned to work for a long time.

Where diluted liquids with low (light) density and viscosity are used, as well as for liquid with good lubricating characteristic, and maximal pressure, pumps with high-speed rotation are used.

Maximum Speed of 1000 R.P.M

This speed is used for lubrication and cooling systems applying diluted oil or liquid, with the viscosity of 10-40.

Maximum Speed of 750 R.P.M

This speed is used for auto-lubricating liquids, having the viscosity of 30-15.

Maximum Speed of 200 - 500 R.P.M

This speed is used for heavy liquids, oils, molasses, pastes, and other liquids having high viscosity.

The maximum speed of stainless steel and brass pumps is the permissible speed of 200 – 500 R.P.M.

Instructions for application of different types of gear pumps, and a six-month guarantee provided for the products of IRAN TOLID

  • Use special pumps manufactured by IRAN TOLID to transfer auto-lubricating materials.
  • Use special pumps manufactured by IRAN TOLID to transfer materials containing hard metal materials (even finer than 0.1 mm).
  • Use balanced and machined couplings during coupling, and frame straightening to provide any vibration.
  • It is recommended hydraulic couplings to be used for viscous (heavy) liquids in order to let the engine works with a lower ampere and better power.
  • It is recommended to use a one-way valve and a fine screen at the beginning of suction tube.
  • It is recommended to use an elbow bending at a 45º angle with at least one-meter intervals, so that the pump can work less noisy and with lesser ampere.
  • Ensure that the pump is full of material, and then start up the engine.
  • To prevent extra expenses, inspect regularly brass bushings, and in case of any clearance even more than 0.5 mm, replace them. Shelf life of the bushings depends on their performance and material used.