SPECIFICATIONS OF LEADING GAS TRACTORS 



(1) Specific gravity = weight (Ibs. per gallon) x 12 



(2) Weight (Ibs. per gal.) = specific gravity 



12 



(3) Baume gravity = 140 



specific gravity 



(4) Specific gravity = 140 -^ 



130 -+- (Baume gravity) 



(5) Indicated horsepower (I.h.p.) = PxLxAxN 



33000 



in which P = mean effective pressure (M.E.P.) in pounds per square inch; 

 L = length of stroke in feet; A = area of piston in inches; N = number of 

 power impulses per minute. 



(6) For steam engines: 

 Ii.p, = 2PLAN 



33000 



(7) For four-cycle, single-acting, throttle-governed gas engines: 

 I.h.p. = PLAN 



33000 x 2 



(8) Brake horsepower (B.h.p.) = 2 x 3.1416 xLxNxF. 



33000 



in which L = length of brake arm; N = r.p.m. of flywheel; F = weight on 

 scale beam. 



(9) Drawbar h.p. = speed (mi. per hr.) x drawbar pull 



375 



(10) Mechanical efficiency^ B.h.p. 



Lh.p. 



