Fitted on pin a of crank 1 is eccentric bushing 5. The outer surface of bushing 5, eccentric to the bore, fits the bearing of connecting rod 6 which is connected to the driven link (not shown). The hub of bushing 5 is concentric to the bore and carries gear 4. Thus the axis of gear 4 coincides with that of pin a of crank 1. Gear 4 meshes with rack 3 which is rigidly attached to yoke 2 whose slot b slides along the extension of pin a of the crank. The number of teeth of gear 4 is designed so that when crank 1 turns through 180°, eccentric bushing 5 turns through 180° in the opposite direction. The stroke of connecting rod 6 depends on the throw of crank 1, i.e. on the relative position of crank 1 and bushing 5. This is changed when rack 3 is shifted by readjusting nuts 7 on rod 8.
$2441$LrG,ML$