2. Fourbar Quick return(急回特性) Definition of the Quick- Return(急回) It is used to describe the fact that the forward stroke is faster than that of the return stroke. The time ratio(Tr defines the degree of quick-return of the linkage C. 慢速 Ko0s=91/92 B =1800+6/1800-6 快透13 Bi K:行程速比系数 D B2. Fourbar Quick return （急回特性） Definition of the Quick-Return(急回) It is used to describe the fact that the forward stroke is faster than that of the return stroke. The time ratio(TR ) defines the degree of quick-return of the linkage. TR =2 / 1 K= f /  s =1 / 2 =180o+ / 180 o - K: 行程速比系数