Pin wheel 1 with pins a rotates about fixed axis A and meshes with teeth d of rack 2 which slides along fixed guides b-b. The profiles of teeth d of rack 2 are along curves which are equidistant from a cycloid of a circle. Wheel 1 has circular locking lug e and rack 2 has concave surfaces e. When driving pin wheel 1 rotates at uniform velocity, driven rack 2 travels at uniform velocity but has dwells. During the dwells, lug c engages concave surfaces e to prevent unintentional motion of the rack.
$2583$PG,3L$