Crank 1 rotates about fixed axis A. Gear 4 is connected by turning pair B to crank 1 and meshes with fixed internal gear 3. If the radii R and r of the pitch circles of the gears comply with the condition: R/r=2, then point C, lying on the pitch circle moves along straight line Ax. Thus the mechanism converts reciprocation of piston 2 along its guides into rotation of crank 1 about axis A.
$1738$GL,4L$