Cyclopedia of mechanical engineering; a general reference work Editor-in-chief Howard Monroe Raymond Assisted by a corps of mechanical engineers, technical experts, and designers of the highest professional standing . Fig. 17 S78 DESKiJM 7H the surface of a ^iven pulli^y, \vc do not y(^t know wliat citlierT„ or T„ actually is; and until \vn do know, we cannot correctlyjirojiortion the belt. Hence we must find another relation betweenT„ and T„ whicli we can combine with equations 5 and 0. Thisrelation is deduced bv a process of liitrlicr matlieniatics, which re-sults as follows: T„ t
Cyclopedia of mechanical engineering; a general reference work Editor-in-chief Howard Monroe Raymond Assisted by a corps of mechanical engineers, technical experts, and designers of the highest professional standing . Fig. 17 S78 DESKiJM 7H the surface of a ^iven pulli^y, \vc do not y(^t know wliat citlierT„ or T„ actually is; and until \vn do know, we cannot correctlyjirojiortion the belt. Hence we must find another relation betweenT„ and T„ whicli we can combine with equations 5 and 0. Thisrelation is deduced bv a process of liitrlicr matlieniatics, which re-sults as follows: T„ toinnion loiraiithn 1,. • (1-2)/,. (7) Treatinir equations 5 and 7 as simultaneous, values of bothT,j and T„ can be found by the regular algebraic solution. As T,,is the larger, the actual area of belt to provide the necessary strengthmust be made to depend upon it. The factors in equation 7 depends ujioii tlir cfiiti-ifnoal force. Fig. 18. developed by the weight of the belt passingarouud the pulley. Itsvalue, found from mechanics, is: w X V .t,6()0 X ;? Having found the maximum pull on llie l)elt, it now remains10 write the eipiation: force = Internal resistance; T^ = l>XhXt. (8) Usually the most convenient way to handle this equation isto assume // and t, and then solve for 0. 279 80 MACHINE DESIGN Snniining up tlu tlieoivticjil treatiiuiit of belt ilcsiirii, \v(!simply combine equations 5, 0,7, and S, and solve for the qnautilytlcsiivd. Discussion of tiie constants involved in tliese e(juations,and of the practical factors controUinij them, is given in tlie fol-lowing : PRACTICAL MODIFICATION. The force of friction F, whichis the same as driving force I, depends on: CoetKcient of friction (/j.) hetween licit and ])ulley; Tightness of the belt; Centrifugal force of the belt; Angle of contact of belt with pulley. The coefKcient of friction (/a), according to experiments andobserved operation of
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