24 



HANDBOOK OF MECHANICAL DESIGN 



22. WR^ of a Connecting Rod, Effective at the Cylinder Center Line, about the 

 Crankshaft Center Line. 



WR^ = r' 



(- + — y 



Fi + Tf4J + 8L2- 



where r = crank radius W2 = weight of the upper or reciprocating part 



L = center-to-center length of connecting of the rod = WrLi/L 



rod Wr = Wi + W2, the weight of the complete rod 



Wi = weight of the lower or rotating part of Li = distance from the center line of the crank- 

 the rod = [Wr(L — Li)]/L pin to the center of gravity of the con- 



necting rod 



23. Mass Geared to a Shaft. — The equivalent flyvi^heel effect at the shaft in 

 question is 



WR^ = h^iWR'Y 



where h = gear ratio 



_ r.p.m. of mass geared to shaft 

 r.p.m. of shaft 



(WR"^)' = flywheel effect of the body in question 

 about its own axis of rotation 



24. Mass Geared to Main Shaft and Connected by a Flexible Shaft. — The effect 

 ,^2)' r>*-j^~ Driven gear of the mass (TT^i?-)' at the position of the driving 



C^^^^j . gear on the main shaft is 



'""■^^ '^^^ TI7P2 _ ^KWR'^y 



^Mainshaff VV K — ("TFTP'VP 



^^n ■ ■ r..nr ^ " 9.775C 



Driving gear 



where h = gear ratio / = natural torsional frequency of the shafting 



_ r.p.m. of driven gear system, in vibrations per sec. 



"" r.p.m. of driving gear C = torsional rigidity of flexible connecting 



{WR^y = flywheel effect of geared-on mass shaft, in pound-inches per radian 



25. Belted Drives. — The equivalent flywheel effect of the driven mass at the 

 L L -^1 driving shaft is 



/HS T\^ WR^ = ^'^'^' 



V4 ^ Vi^ y " 9.775C 



Driven \ ^ Driving 



puiiey pulley 



where h = Rx/R C = R^AE/L 



r.p.m. of pulley belted to shaft A = cross-sectional area of belt, in sq. in. 



~ r.p.m. of shaft E = modulus of elasticity of belt material in 



[WR-y = flywheel effect of the driven body tension, in lb. per sq. in. 



about its own axis of rotation R = radius of driven pulley, in in. 



/ = natural torsional frequency of the L = length of tight part of belt which is clear 



system, in vibrations per sec. of the pulley, in in. 



