General Forms of Index Ratios and Generation of Variable Index Ratios by Series-Connected Geneva Mechanisms with Single or Multiple Driving Pins

Abstract

General forms of the index ratios in series-connected Geneva mechanisms having single and multiple driving cranks, including the cases of alternately driven slots and internal Geneva mechanisms, are given. Cases eliminating the jerk and acceleration at the beginning and end of the motion period are defined. Possible slot-number and pin-number combinations are investigated. Index ratios are defined in terms of a “parameter of variance.” By redefining the parameter of variance in a series-connected Geneva mechanism drive the new position of the crank driving the output Geneva wheel is redefined to generate a new value of the index ratio. Geneva mechanisms can be designed to generate index ratios that can be varied up to 346.9578. Along with the design equations, complete design tables are given for the selection of Geneva mechanism drives to generate constant or adjustable index ratios within desired range, thus broadening the design opportunities with Geneva mechanisms. Design examples are included.