GB653762A - Improvements in or relating to overload release clutch mechanism and electrically driven apparatus comprising a plurality of such mechanisms - Google Patents

Abstract

653,762. Overload-release clutches. PHILIPS ELECTRICAL, Ltd. Oct. 1, 1948, No. 25620. Convention date, Oct. 4, 1947. [Class 80(ii)] An overload release clutch, which re-engages automatically when the overload is cleared, comprises a floating intermediate member 4, drivingly connected by a pawl 8 to a driving ratchet-wheel 3; by a torqueresponsive tension spring 11 to a driven wheel 5; and by a one-way jamming roller 14 to an arresting member 6 which holds the intermediate member 4 in a stationary declutched condition during overload and itself has a tongue-and-slot limited connection 16 with a fixed member 17, whereby on overload-release the arresting member makes a limited backward movement which may be used for opening or closing a switch 19 in the circuit e.g. of the driving motor or of signalling apparatus, or for mechanically operating signalling: counting or hydraulic apparatus. The intermediate member 4 carries the pawl 8 on a pivot-pin 7 passing through an arcuate slot 13 in the driven wheel 5 to permit limited turning movement between the members 4, 5, by which movement the pawl 8 is pivoted into and out of engagement with the driving ratchet-wheel 3 by thrust against a pawl-recess 22 of one or other radially projecting end of a single-turn spring 20 carried in a circular recess 21 in the driven wheel 5. The pawl 8, which is as described in Specification 648,555, is channel-shaped and engages the driving ratchet 3 through a roller 9 pressed by a spring 10. Normal drive, Fig. 2, in the direction of the arrow P, passes from the driving ratchet 3, through the pawl 8, intermediate member 4, and tension-spring 11, to the driven wheel 5, the pawl 8 being pressed down into engagement by the left end (Fig. 2), of the circular spring 20. Overload causes the driven wheel 5 to lag behind, stretching the tension-spring 11 until eventually the other end (right, Fig. 2), of the circular spring 20 lifts the pawl 8 off the driving ratchet 3, thus disengaging' the clutch. The intermediate member 4 is now free to execute a limited movement backwards relatively to the driven wheel 5 under the influence of the tension-spring 11, during which movement the jamming roller 14 engages and turns the arresting- member 6 to the limit of its backward movement, opening the motor-switch 19. When the overload is cleared the tensionspring 11 returns the parts to the clutchengaged position Fig. 2, the arresting-member 6 being returned by the switch-spring or by an additional spring. One or more of these clutches may be used to permit arresting one or more shafts in predetermined positions, e.g. for tuning radio. Specification 634,781 also is referred to.