冈 10 60 P B and Cfalls outside the reetangular area bounded by the lines of constant 7.0 A,class(c)operation is indiented.Crank and rocker linkages [elnss (a) operation]included in henvily outlined area are covered in this book. 2.0 Example: Data:Drive erank =4";Connecting Rod -10" 6.0 Follower Crank =8";Line of Centers 12" Pind:(1)Class of operation. 3.0 (2)Variation in link ratios possible without changing class of operstion. 5.0 Solution (see figure 8): 4-碧-26；B=g-2:c-是-8 4 4.0 Drive crank is the shortest link.Refer to figure 7.Point (B -2. 4.0 C=3)falls within oblique reetangular area bounded by lines A -2.5. Therefore s()operation is indieated 5.0 1,A -2.5,B =2 C may be varied from 1.5 to 3.5 1,A -2.5,C=3 B may be varied from 1.5 to 4.5 3.0 1,B -2,C=3 A may be varied from 2 to4 6.0 2 2.0 7.0 1.0 1.0 2.0 3.0 40 5.0 6.0 7.0 B Fig.7 POUR-BAR LINKAGE CLASSIFICATION CHART B Linkage whose ratios B and C determine a point which lies in the oblique reetangular area bounded by lines of eonatant ratio A operates Crank and Rocker or as a Drag F1g.8 Link.Ex) '1. Fig; 7 FOUR~BAR LINKAGE CLASSIFICATION CHART Linkage whose ratios Band determine a point which lies in the oblique rectangular area bounded by lines of constant ratio Link, operates as a Crank and Rocker or as a Drag :",,-:..,' ~" .;.. . "' ;~,;.it1i'&"~;,:J!f;;t. y+'",,,;,,;, - iii Band C falls outside the rectangular area bounded by the lines of constant class (c) operation is indicated, Crank and rocker linkages (class (a) operation) included in heavily outlined area are covered in this book. '1; Example: Data: Drive crank = 4" ; Connecting Rod = 10" Follower Crank = 8"; Line of Centers = 12" Find: (1) Class of operation. (2) Variation in link ratios possible without changing class of operation. Solution (see figure 8): - = 2, 10 5; = - = 2; C = - = Drive crank is the shortest link, Refer to figure 7. Point (B = 2 C = 3) falls within oblique rectangular area- bounded by lines =2. Therefore class (a) operation is indicated = 2, = 2 C may be varied from 1.5 to 3. = 2. , C = 3 may be varied from 1.5 to 4. = 2, C = may be varied from 2 to 4 bs. I\~ bs. '-' Fig, III ..~.. "'. ~~- ...c