Pump types

• Non-positive displacement pump

  • Low pressure - high displacement pump
  • Not suitable for use in most systems
• Simple positive displacement pump

  • There is a positive seal between suction and discharge
  • pump can attaint a high pressure delivery, so is ideal for hydraulic applications
• External gearwheel pump

  • Most common type is the spur gear pump
  • This consists of a drive and a driven gear, enclosed in closely fitting housing
  • The gears rotate in opposite directions, meeting at a point in the housing between the inlet valve and chamber
  • As the gears separate, fluid is drawn into the inlet chamber, then trapped between the great teeth and housing
  • The fluid is then carried in 2 different directions to the outlet chamber, and forces out as the gear teeth re-mesh
• External gearwheel pump


  Has considerable losses due to tip and end clearance