| 33000 ) 113097 | 60 ( 342.72 = horse power of engine. |
| 99000 | |
| 14097 | 6 |
| 13200 | 0 |
| 897 | 60 |
| 660 | 00 |
| 237 | 600 |
| 231 | 000 |
| 6 | 6000 |
| 6 | 6000 |
In working out the calculation, the ciphers that are decimals and are on the right hand are neglected or taken no account of, because they represent no value and may therefore be discarded.
Thus the area of the piston is 314.1600 inches, the two right hand ciphers having no value. Again the lbs. pressure on the piston is 18849.60 lbs., and the right hand cipher, having no value, is discarded. The inch lbs. per stroke is 565488.0, and the decimal cipher, representing nothing, is discarded when multiplying by the 2.
We have in this case taken no account of the fact that the piston rod prevents the steam from acting against a part of the piston area during one stroke; hence for correct results we must subtract from the area of the piston one half the area of the piston rod.
The horse power thus obtained is that which the engine receives from the steam, and is more than the engine is capable of exerting to drive machinery, because a part of this power is consumed in overcoming the friction of the working parts of the engine.
TESTING THE HORSE POWER OF AN ENGINE.
Fig. 3356.