The effects of play in the joints of a function-generating mechanism

Abstract

Two methods are presented for the analysis of errors caused by play in the revolute joints of a precision function generating linkage. The error occurring in the output angular displacement of a four-bar linkage is shown to be maximum for a given angular input when the vectors representing the clearances are parallel to the coupler. If the input variable is within a given range, maximum error occurs when the transmission properties are the worst. An approximate formula for the error is also given, which can be used for specifying clearances to keep the errors within permissible limits. It is found to be very useful in the analysis to replace a joint with play by an imaginary link with ideal joints.