Fit of Elastic Sleeve–Pin Couplings with Shafts

Abstract

Defects in the joints of elastic sleeve–pin couplings with shafts are analyzed. Defects such as the wear of half-coupling sockets and the distortion of keys and grooves on the shaft and within the half-couplings are due to loose coupling–shaft connection. Analysis of the appropriate manufacturing standards shows that most of the recommended fits do not ensure the required working life on account of gaps where relative motion of the supposedly contacting surfaces is possible. A method is proposed for selecting the fits in connecting elastic sleeve–pin couplings with shafts, so as to improve the reliability and working life. As an example, fits are calculated for half-couplings on a shaft for N 090.40 gearboxes, depending on the assembly method. The fits ∅50H8/v7 and ∅50H8/u8 are obtained; each one differs from the standard recommendation. The ∅50H8/v7 fit has considerable tightness and ensures that there will be no twisting in torque transfer. The most expedient option is the ∅50H8/u8 fit, obtained for assembly by bush heating, since it is more stable over the tightness range with less machining accuracy of the shaft, and hence the machining costs for the shaft will be lower.