Proportions for high speed engines . be uniform as in ^ig. 2. Bendingmay be conceived to take place as follows:The equal forces .^n Fig, 2 applied success-ively from the fixed end a bend the pinmore and more as h is approached. The forc-es near the end a may chaise such a deflec-tion that the pin no longer bears hard onthe hearing to-zard the end b. The forceson the pin are consequently decreased to-ward the end b where the pin does not bearhard and increased toward the end a wherethe pin does ^to^ bear hard on the the case of a pin of comparatively gi~eatlength and small diameter,
Proportions for high speed engines . be uniform as in ^ig. 2. Bendingmay be conceived to take place as follows:The equal forces .^n Fig, 2 applied success-ively from the fixed end a bend the pinmore and more as h is approached. The forc-es near the end a may chaise such a deflec-tion that the pin no longer bears hard onthe hearing to-zard the end b. The forceson the pin are consequently decreased to-ward the end b where the pin does not bearhard and increased toward the end a wherethe pin does ^to^ bear hard on the the case of a pin of comparatively gi~eatlength and small diameter, it ma-y be easily seen that the pressuretoward a raa^- become extremely large and cause excessive wear. Thispre<^ssure, and hence the deflection should be kept within reason-able limits and it appears that the diameter and length of thecrank-pin shou! bear some definite relation to each other, A mini-mum deflection must be assumed which will give a reasonable distri-bution of pressure. Kxpressing the deflection in terms of the. T^ig. 3. lent^th of the pin we get the relation ^= M-1 where 6 is a satisfactory deflection and M is some constant deter-mined hy experience. The crank pin mB.^ be considered as a heEim fixed at oneend, for both side-crank and center-crank engines. Indeed, thecenter-crank is an especially aggravated form because during partof the stoke the fly-vheel drives through the pin and gives a largeforce at the free end in the same direction as the force trans-mitted through the connecting rod. The deflection of a beam fixedat one end and free at the other is 6 For circular sections and 648P-l4 Buthence 6- I = P = Bld; 4 6=^ BB-l _ and thereforeor But since 1 TTE d » ^ =: constant = Ka 1 = Kd P = B • 1 • d ~ 4 p, TT D^ = -0 - and d rr ^J^If x D or d = C-D , where ^ constant. The diameter of the crank pin for each en^^ine was plottedas an ordinate and the diameter of the cylinder as an ahscl ss?., Acurve was drawn to >-epresent the mean o
Size: 1682px × 1485px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjecttheses, bookyear1902
