When a starting treadle (not shown) is depressed, plate 1 is pulled to the right against the tension of spring 2. Latch a, in this motion, engages collar 3 and moves it together with latch 4 to the right against the tension of spring 5. As soon as latch 4 is disengaged from nose d of friction roller cage 6, the latter is turned clockwise by spring 7 which is secured with one end to roller cage 6 and the other to collar 8, keyed to shaft 13. As roller cage 6 revolves, its lugs b push rollers 9 of the clutch so that they climb up the cam surfaces of cam member 10 and become wedged between the cam member and hardened steel ring 11 press-fitted into revolving flywheel 12. Since cam member 10 is keyed to shaft 13, the latter begins to revolve clockwise, together with collar 8. At this, cam c of collar 8 comes into contact with cam e at the end of plate 1, turning the plate downward about fixed axis D. This disengages collar 3 from latch a, allowing spring 5 to shift latch 4 back to its initial position, ready to engage nose d of roller cage 6 when the cage and shaft 13 have made one complete revolution. When nose d and cage 6 are stopped by latch 4, rolls 9 roll along cam member 10 releasing the clutch so that shaft 13 stops. Before the clutch disengages, spring 7 is tensioned again. Thus, shaft 13 makes a single revolution when the starting treadle is depressed and does not repeat even if the treadle remains depressed. For the clutch to be engaged for the next single revolution, the treadle must be released and depressed again.
$3261$CmL,C$