WORKING OF GEAR PUMP EXPLAINED !!

External gear pumps are a popular pumping principle and are often used as lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in engines.Gear pumps are also widely used in chemical installations to pump high viscosity fluids.

Working of gear pump :-

External gear pumps are similar in pumping action to internal gear pumps in that two gears come into and out of mesh to produce flow.  However, the external gear pump uses two identical gears rotating against each other -- one gear is driven by a motor and it in turn drives the other gear.  Each gear is supported by a shaft with bearings on both sides of the gear.

1.  As the gears come out of mesh, they create expanding volume on the inlet side of the pump. Liquid flows into the cavity and is trapped by the gear teeth as they rotate.

2.  Liquid travels around the interior of the casing in the pockets between the teeth and the casing -- it does not pass between the gears. 

3.  Finally, the meshing of the gears forces liquid through the outlet port under pressure.
Because the gears are supported on both sides, external gear pumps are quiet-running and are routinely used for high-pressure applications such as hydraulic applications. With no overhung bearing loads, the rotor shaft can't deflect and cause premature wear.

Advantages :-

• High speed
• High pressure
• No overhung bearing loads
• Relatively quiet operation
• Design accommodates wide variety of materials

Disadvantages :-

• Four bushings in liquid area
• No solids allowed
• Fixed End Clearances

Applications :-

Common external gear pump applications include, but are not limited to:

• Various fuel oils and lube oils
• Chemical additive and polymer metering
• Chemical mixing and blending (double pump)
• Industrial and mobile hydraulic applications (log splitters, lifts, etc.)
• Acids and caustic (stainless steel or composite construction)
• Low volume transfer or application