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YILDIZ’s simple “gear-within a gear” principle has only two moving parts. It is the secret of dependable, efficient operation of all positive displacement YILDIZ POMPA’s PUMPS. The positive displacement of liquid is accomplished by the complete filling of the spaces between the teeth of the rotor and idler gears. The only limiting factor to peak performance in YILDIZ POMPA, as with all rotary pumps, is that the liquid pumped must be comparatively clean.

With every revolution of the pump’s shaft, a definite amount of liquid enters the pump through the suction port. This liquid fills the spaces between the teeth of the rotor and the idler. The crescent on the pump head splits the flow of liquid as it moves smoothly towards the discharge port. The idler gear, which carries the liquid between its teeth and the inside surface of the crescent is connected to pump cover. On the otherhand, rotor gear which is rotated directly with pump shaft delivers the liquid between gear teeth and crescent’s souter surface.



Q : 0,100 – 250 m³/h
Hm : 1 ~ 15 Bar
T : 0 ~ 200 ºC
n : 20 – 1720 rpm
Visc. : 100 ~ 250.000 SSU


  • Fuel Oil Service Tanks, Gasoil, Diesel Tankers
  • Resin and Polymer
  • Asphalt and Bitumen
  • Paper and Paint/dye industry
  • Circulation of Hot Oil (limited)
  • Medicine, Chemical and Detergent Industry
  • Food Industry.


  • Pump Body, covers: Pig Cast Iron, Spheroidal Cast ıron, Cast Steel, AISI 304/316 CrNi Stainless Steel
  • Gears : Spheroidal Cast ıron, Cast Steel, AISI 304/316 CrNi Stainless Steel
  • Bearings : Snbz 12 bronze, carbon graphite, slicon carbide, hard metal coated steel, bearing
  • Sealing : Soft Seal or Packing Gland, Rotatherm Seal, Lip Seal, Mechanical Seal, Cartridge Type Mechanical Seal



The yellow colored portion at side indicates the liquid as it enters the suction port area of the casing and the area between the rotor teeth and corresponding concave area between the idler teeth. The two black arrows indicate the pump rotation and progress of the liquid.

Notice the progress of the liquid through the pump and between the teeth of rotor idler gear. Also, note how the crescent shape on the head divides the liquid and acts as a seal between the suction and discharge ports.

This illustration shows the pump in a nearly flooded condition just previous to the liquid being forced into the discharge port area. Notice how the gear design of the idler and rotor form locked pockets for the liquid to guarantee absolute volume control.

The view shows the pump in a completely flooded condition and in the process of discharging the liquid through discharge port. The rotor and idler teeth mesh, forming a seal equidistant between the both ports, forcing liquid out the discharge port.



The pumps are typically (when viewed from the shaft end) designed as clock-wise rotation; that is, the sucking mouth (inlet) is on the right and the discharge mouth (outlet) is on top side.

For reverse operation:

You can operate your pumps in both directions. However, changing rotation direction of the pump shaft changes the pumping direction of the liquid; that is you can use both mouths of your pumps as the sucking mount or the discharge mount. Otherwise, it may not be able to perform the bypass operation.




This pumps have casings that can be turned to eight positions. This allows ports to easly match piping. Relief valve must point to suction port in all cases.