Lever 1 and ratchet wheel 3 turn independently of each other about fixed axis A. Lever 1 turns freely while ratchet wheel 3 is secured rigidly to the shaft. As driving lever 1 oscillates about axis A, pawl 2, mounted on the lever and actuated by spring 4, engages ratchet wheel 3, turning it intermittently with dwells of adjustable length. Mounted on the support is collar 6 having projecting segment 5 serving as a shield for the ratchet wheel. Collar 6 can be secured by setscrew 7 in any position with respect to the ratchet wheel. Shield 5 disengages pawl 2 from ratchet wheel 3. By setting collar 6 in various positions it is possible to adjust the length of the dwell of the ratchet wheel.
$138$SL,L$