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# Air Motors

The application of the gas laws to Air Motors
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Contents

## Air Motors

Work done by Air

### Isothermal Operation

Work Done =

It is not possible to expand the Air down to Atmospheric Pressure. By opening the valve early the small loss in work done is accompanied by a large decrease in the Swept Volume.

Work output = Area of Diagram =

Example:

[imperial]
##### Example - The application of the gas laws to Air Motors
Problem
A reciprocating Air Motor of bore 13.54 in. and Stroke 18 in. is supplied with Air at and 90 psi. Find the Work output per cycle with complete expansion to 15 psi. Find also the percentage loss of output resulting from a decrease of stroke to 12 in. with incomplete expansion. Neglect Clearance and take the Index of expansion as 1.25.
Workings

Bore = 13.54 in. and Stroke = 18 in.

The Stroke is now reduced to 12 ins.

Work out put per cycle is:
Therefore the loss of Power is:
Solution
Work out put per cycle is

The loss of Power is