FIG. 223. Side View of Tom Thumb Tractor with Hood Sides Removed to Show Arrangement of Power Plant Parts and 12. SPECIFICATIONS. Rated Tractive H.P., Governor, Throttling. Radiator. Fuel-tank Capacity, 20 Gallons. No. of Speeds, 2 Forward, 1 Re verse. Low Speed, 2 Miles per Hour. High Speed, 2 Miles per Hour. Belt Pulley Diameter, 16 Inches. Belt Pulley Width, 7 Inches. Bearings, Roller throughout Gear. Drive Wheel, see Remarks. Drive Wheel Width, see Remarks. Front Wheel Diameter, 42 Ins. Front Wheel Width, 6 Inches. Wheel Base, 7 Feet. Width of Machine, 7 Ft. 3 Ins. Length of Machine, 11 Feet. Height of Machine, 6 Feet. R.P.M. Engine Shaft, 800. Shipping Weight, 4200 Pounds. Circle Machine can Turn in, 15Foot Circle. Remarks: Endless Drive Track, 48 Inches Long, 16 Inches Wide. CHAPTER XII. MISCELLANEOUS RULES AND FORMULÆ. A Collection of Useful Rules, Tables and Formulæ That Will Prove of Value to the Student, Mechanic or Farmer, These Include Additional Rules for Figuring Horse-power. for Estimating the Capacity of Tanks, Strength of Materials, U. S. and Foreign Conversion Tables and Other Interesting Information of a Miscellaneous Nature. USEFUL RULES, TABLES AND FORMULÆ RULES FOR CALCULATING HORSE-POWER. To calculate the horse-power of any 4-cycle motor, the following general formula is always used, this giving the output of a single cylinder and must be multiplied by the number of cylinders for multiple cylinder engines. P=pounds per square inch. R= the number of revolutions per minute. The pressure in any engine is assumed to be a mean effective pressure or average pressure throughout the stroke, and is written M. E. P. For gasoline engines of the usual 4-cycle automobile type this pressure can be assumed at between 75 and 100 pounds, it, of course, varying with the general design. The actual M. E. P. of an engine which has already been built can be determined by the manograph, which records by means of a streak of light the outline of the indicator card, which, if desired, can be permanently retained by means of a photographic plate. It can also be determined at speeds under 500 R. P. M. by diagrams produced by ordinary steam engine indicators, but these are not accurate when used with high speed gasoline engines, the manograph being far superior. |