Q. How would you find the horse power of an engine? A. Multiply the area of the piston by the average pressure, less 5; multiply this product by the number of feet the piston travels per minute; divide the product by 33,000; the result will be horse power of the engine.
Q. How will you find the area of piston?
A. Square the diameter of piston and multiply it by .7854.
Q. What do you mean by squaring the diameter? A. Multiplying it by itself. If a cylinder is 6 inches in diameter, 36 multiplied by .7854, gives the area in square inches.
Q. What do you mean by average pressure? A. If the pressure on boiler is 60 pounds, and the engine is cutting off at 1/2 stroke, the pressure for the full stroke would be 50 pounds.
Q. Why do you say less 5 pounds?
A. To allow for friction and condensation.
Q. What is the power of a 7 x 10 engine, running 200 revolutions, cutting off at 1/2 stroke with 60 pounds steam? A. 7 x 7 = 49 x .7854 = 38.4846. The average pressure of 60 pounds would be 50 pounds less 5 = 45 pounds; 38-4846 x 45 = 1731.8070 x .333 1/3, (the number of feet the piston travels per minute) 577,269.0000 by 33,000=17 1/2 horse power.
Q. What is a high pressure engine? A. It is an engine using steam at a high pressure and exhausting into the open air.
Q. What is a low pressure engine? A. It is one using steam at a low pressure and exhausting into a condenser, producing a vacuum, the piston being under steam pressure on one side and vacuum on the other.
Q. What class of engines are farm engines?
A. They are high pressure.
Q. Why?
A. They are less complicated and less expensive.