GB643528A - An improved torque-limiting coupling - Google Patents

Abstract

643,528. Overload slip clutches; gearing for stopping machinery; shaft couplings. SOC. AUXILIAIRE D'INDUSTRIE SADI, S.P.R.L.. Dec. 30, 1947, No. 34787. Convention date, Oct. 14, 1939. [Class 80(ii)] An overload slip clutch comprises a plurality of balls 18, Fig. 1, carried in bores in one (as shown, the driving) clutch member 2 and urged by individual springs 19 to co-act with cam recesses in a disc 6 splined to the other clutch member 4, the cam recesses being formed by hollow cylindrical elements 12 mounted in the bores in the disc 6 and having their outer ends internally bevelled to form cam faces 13, Fig. 4, of varying inclination round the elements. A ring 8 bolted to the member 2 retains the disc 6 on the member 4 with slight axial play. The springs 19 locate on pins, 21 secured to a ring 20 rotatable on a screw thread on the member 2 to adjust the maximum torque transmissible, above which the balls 18 are forced out of the cam recesses to allow clutch slip until the overload ceases. Three or more grooves 15 in each element 12 co-act selectively with a pin 17 slidable in the disc 6 so that the maximum torque transmissible may be further adjusted by turning the elements 12 to present differently inclined parts of the faces 13 operatively to the co-acting balls 18. Different elements 12 may be differently orientated-in their bores to provide fine steps of adjustment. As shown, there are three grooves 15 at 90 degrees intervals to allow equal, or different but interchangeable, conditions of maximum torque transmission in the two directions of rotation. The maximum torque transmissible may also be varied by omitting some of the balls 18. In order automatically to disable the driving means upon overload in either or both directions of rotation, one or more of the balls 18 have no co-acting spring 19 but each acts through a further ball 32 on a cam-faced slider 30 to cause the latter resiliently to press a friction pad 28 into driving contact with a ring 23 on the occurrence of overload. The ring 23 is freely mounted on the member 2 and carries an abutment 24 which, when the ring turns, co-acts with one or other of two stops (not shown) mounted circumferentially on either side thereof and one or both of which are displaceable to actuate input torque interrupting means such as an electric motor control switch, a driving clutch control lever or an I.C. engine ignition switch. The Specification as open to inspection under Sect. 91 describes also the conversion of the clutch to a resilient shaft coupling by the screwing, of the ring 20 down so far that the pins 21 prevent the balls 18 from ever completely leaving the cam recesses. This subject-matter does not appear in the Specification as accepted.