Proposed Shaft Coupling Based on RPRRR Mechanism: Positional Analysis and Consequences

Abstract

This study proposes a solution for the transmission of rotation motion between two shafts with crossed directions. For constructive simplicity, the solutions including the planar pair were preferred and, from the two variants, namely structurally symmetric, revolute–planar–revolute (RPR), or asymmetric RRP, the last was selected. The resulting solution, RPRRR, is a non-Denavit–Hartenberg (non-D–H) mechanism. The D–H methodology is laborious since the structure of the equivalent mechanism is more complex than the actual one. For this reason, in the present paper, the kinematic analysis of the mechanism uses geometrical conditions of existence of the planar pair. The system is solved analytically and two main conclusions result: for a set of constructive data and a stipulated position of the driving element, two different assembling positions exist and a rotation motion occurs in the final revolute joint, but in the internal revolute pairs, the motion is oscillatory. The correctness of the theoretical results was corroborated by a CATIA model. The mechanism was also constructed and smooth running was noticed. Two main concerns were considered for the design of the mechanism: avoiding mechanical interference between the elements and estimating the stresses and deformations.