Crank Linkage Research Articles

A long-period vertical vibration isolator for gravitational wave detection

Abstract A novel design for a long-period passive vertical suspension system based on a torsion crank linkage is presented together with proof-of-concept measurements. A working range of centimetres and periods in excess of 20 s were obtained in agreement with theory. The design is cascadable with a horizontal isolator for 3D isolation.

Theory of symmetrical mechanisms

The paper deals with double crank linkages with symmetrical properties. Concepts like coordinate, kinematic, mass and force symmetries are strictly defined, and input motions providing equal kinematic status of the cranks are specifically discussed. An infinite number of symmetrical motions are shown to exist, and appropriate procedures to derive such motions are developed. A similar analysis is presented to cover the force symmetry problem, and a scheme for equivalent power distribution between the cranks is offered. Numerical analyses of sample linkages shows that considerable improvement in the dynamic performance is possible if the theory is followed.

Analysis and design of RCCC linkages

A new technique is proposed for the analysis and design of spatial linkages. This technique is based on: (a) modeling closed loops as two open-loop chains, (b) the use of two special types of 4 × 4 matrices, (c) the existence theorem for systems of implicit functions and (d) special criteria of force transmission. Applying this technique to the RCCC mechanism yields the following results: (a) simplified equations for the link positions, (b) conditions for the existence of single and double crank linkages, (c) conditions for the mechanism to satisfy so as to avoid singular configurations and (d)design conditions for favorable force transmission. These new results are used to design classes of RCCC mechanisms in which the jamming movements in the cylindrical pairs are minimized.

Stability of a Four-Bar Linkage with Flexible Coupler

The undamped transverse vibration of a flexible coupler in a crank and rocker four-bar linkage is shown to be governed by an inhomogeneous Hill's equation. Analysis of the corresponding homogeneous equation shows that the vibration may be unstable and that at a prescribed input speed stability depends on the inertia effects of the follower as well as on the characteristics of the coupler. Stability boundaries may be determined by digital computation, and an illustrative chart is worked out for a particular case.