This paper presents a kinematic analysis and a redesign of a variable-speed transmission mechanism. The mechanism is a seven-bar linkage where the rotation of the input crank is converted into the oscillation of the output link. The input crank rotates at a constant speed and the output link consists of an overrunning clutch mounted on the output shaft. The angle through which the clutch oscillates, for each revolution of the input crank, can be adjusted by a control arm. This arm allows a fixed pivot to be temporarily released and moved along a circular arc about a permanent ground pivot. The paper shows how to determine the angle of oscillation of the clutch for a specified position of the fixed pivot. The paper also investigates the extreme positions of the clutch corresponding to the extreme positions of a point on the coupler link. For this reason, the paper investigates the geometry of the path traced by a coupler point. The work shows how to determine the location of the ground pivot of the control arm which will cause the clutch to remain stationary during a complete rotation of the input crank. Then the paper shows how to design the control arm by using these conditions; i.e., the conditions for a redesign of the mechanism are investigated. A novel technique, in which kinematic coefficients are obtained with respect to an independent variable, is presented. This technique decouples the position equations and gives additional insight into the geometry of the mechanism.

This content is only available via PDF.
You do not currently have access to this content.