External 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

External vs internal gears

An external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, an internal gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, an internal gear is one with the pitch angle exceeding 90 degrees. Internal gears do not cause output shaft direction reversal.

Gears types

External vs internal gears
Spur
Helical
1 Skew gears
Double helical
Bevel
Spiral bevels
Hypoid
Crown
Worm
Non-circular
Rack and pinion
Epicyclic
Sun and planet
Harmonic drive
Cage gear
Magnetic gear

Gears

Gear is an mechanical component which is used to transmit the power from one shaft to another without any slip,it has teeth on its surface

Method of ignition

SI engines, mixture is uniform (conventional engines), mixture is non-uniform (stratified-charge engines) ignition is by the application of external energy (to spark plug)

CI engines, ignition by compression in conventional engine (Diesel engine), pilot injection of fuel in gas engines (eg, natural gas and diesel fuel – dual fuel engines)

AIR STANDARD CYCLES

AIR STANDARD CYCLES
Because the products of combustion are not too different from air (in terms of thermodynamic properties) we can analyse the engine cycle as a series of reversible non-flow processes using air as the working fluid throughout the cycle.This is known as an air-standard cycle.

IC engine

An Internal Combustion engine is one in which the heat transfer to the working fluid occurs within the engine itself, usually by the combustion of fuel with the oxygen of air