| Pumps - Positive displacement - Rotary pumps |
| Video |
| A positive displacement pump. For each revolution of the pump, a fixed volume of fluid is moved regardless of the resistance against which the pump is pushing. It is self-priming, and gives practically constant delivered capacity regardless of the pressure. The rotary pump consists of a fixed casing containing gears, cams, screws, plungers or similar elements actuated by rotation of the drive shaft. A number of pump types are included in this classification, among which are the gear pump, the screw pump, and the rotary vane pump. |
| Rotary pumps are useful for pumping oil and other liquids of high viscosity. In the engine room, rotary pumps are used for handling lube oil and fuel oil and are suitable for handling liquids over a wide range of viscosities. Rotary pumps are designed with very small clearances between rotating parts and stationary parts to minimize leakage (slippage) from the discharge side back to the suction side. Rotary pumps are designed to operate at relatively low speeds to maintain these clearances. The operation at higher speeds causes erosion and excessive wear which result in increased clearances with a subsequent decrease in pumping capacity. Classification of the rotary pumps is generally based on the types of rotating element. |
| Types of rotary pumps: |
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| Gear pump | Internal gear pump | Gear pump | Internal gear pump | Engine lubrication |
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| Single crew pump | Double screw pump | Triple screw pump | Worm screw pump | Worm screw pump |
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| Lobe pump | Lobe pump | Vane pump | Vane pump | Vane pump |
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| Peristaltic (Hose) Pump | Peristaltic (Hose) Pump | Peristaltic (Hose) Pump |