Link 3 oscillates about fixed axis B. It is driven through connecting rod 2 by the oscillation of crank 1 about fixed axis A. By means of rolls a, link 3 imparts intermittent rotary clockwise motion to ratchet wheel 4 about axis B. The angle of rotation of link 3 is varied by changing the length of crank 1. This is done by adjusting slider 5 along slot b and clamping it in the required position.
$1811$LR,6L$