42 LEATHER BELTING 



^_ . 



2><I0 0.00758/0 +I 



Having determined a value for p, the horsepower can readily 

 be determined from the general formula 



33000 



It now only remains to connect the formula for p with the 

 initial tension in the belt as it is at rest on the pulleys. This 

 connection is established by the formula 



_-- 



Initial - . (<)) 



12 



This formula will give values for fo and t m respectively, accord- 

 ing as we substitute for A, 240 or 320 for machine belts, and 

 1 60 or 240 for countershaft belts. The above are the formulae 

 on which the horsepower tables on pages 91 to 94 are based. 

 If, after having determined the values of p, to and t m , 

 t\ and fa are desired, the following formulas may be used: 



h-^+f ....... do) 



3 



fe-'J^ ....... (zx) 



3 



Formulas (10) and (n) may be used if it is desired to deter- 

 mine the initial tension in a horizontal belt, which theoretic- 

 ally is slightly different from that which should be used for 

 a vertical belt, to which formula (9) applies. This tension, 

 however, differs so little from that of a vertical belt, except 

 in the case of belts of extraordinary length, that there is no 

 practical end served by determining it separately. The 

 formula, however, is given here simply as a matter of interest: 

 For long horizontal belts 



