Design and Application Criteria for Connecting Couplings

Abstract

A classification of couplings as rigid, misalignment-compensating, torsionally flexible, and combination purpose is proposed. Selection criteria for two basic subclasses of misalignment-compensating couplings are derived, some standard designs are analyzed, and modifications of Oldham and gear couplings in which compensatory motion is accommodated by internal shear in thin elastomeric layers instead of reciprocal sliding are described. The new designs demonstrate very high efficiency and exert substantially reduced forces on the connected shafts. Factors determining the influence of torsionally flexible couplings on transmission dynamics are formulated as reduction of torsional stiffness, enhancement of damping, modification of nonlinearity, and inertia distribution. Compensation properties of combination purpose couplings are investigated analytically and a “design index” is introduced. A comparison of important characteristics of some commercially available types of combination purpose couplings is performed, to facilitate an intelligent comparison and selection of various coupling types. A line of approach for the improvement of torsionally flexible / combination purpose couplings by using highly nonlinear elastomeric elements is suggested.