GB643799A - Improvements in or relating to clutch mechanisms - Google Patents

Abstract

643,799. Overload slip clutches. KODAK, Ltd. Feb. 26, 1948, No. 5863. Convention date, Feb. 27, 1947. [Class 80(ii)] Relates to clutches of the kind in which power is transmitted, from a driving shaft to a driven member rotatably mounted thereon, by a coil spring encircling and normally frictionally driven by the shaft, and in which a tensioned torque-limiting spring is provided between the coil spring and driven member to cause clutch disengagement during overload. As shown, in a form in which bi-directional overload slip drive is effected by a single coil clutch member 46, Fig. 1, encircling a driving shaft 16, the opposite ends of the coil 46 are fast with sleeves 20, 22 having axial drive lugs 40, 42, Fig. 4, locating with circumferential play in a slot 41 in a driven member 18 rotatably mounted on the shaft 16. The coil 46 is bridged by an adjustably tensioned spiral spring 27 which acts to bias the lugs 40, 42 into driving engagement with the ends of the slot 41 as shown, when the coil 46 is also drivingly contracted about the shaft 16. The arrangement is such that drive from the coil 46 always passes through the spring 27 on to the appropriate lug 40 or 42, so that, regardless of the direction of rotation of the shaft 16, drive ensues until the torque loading on the member 18 is sufficient to overcome the spring 27 and drive back the operative lug 40 or 42, expanding the coil 46 out of contact with the shaft 16 and breaking the drive. The spring 27 acts between a rim 29 on the sleeve 20 and a drum 26 which is located relative to the sleeve 22 by a set screw 34 engaging one of a number of circumferentially spaced cut-outs 32 on the drum, and may be rotated relative to the sleeve to adjust the tension of the spring 27 by slackening off the screw 34 and rotating the drum by means of a tool engaging the cut-outs 32 through a slot (not shown) in the sleeve. In Fig. 5 (not shown), in a form which may allow slip at different overloads in the two directions of rotation, bi-directional drive is supplied by two oppositely acting clutches of the kind referred to mounted on a driving shaft on either side of a driven pulley, one end of each coil and its corresponding spiral torque-limiting spring being secured to a loose sleeve common to both clutches, and the other ends of the coil and torquelimiting springs in each clutch being secured to a sleeve individual to the clutch and having a circumferential lost-motion slot engaged by a drive pin on the pulley. Each of these latter sleeves has a further lost-motion connection with the loose sleeve, on which the pulley is freely journalled. The arrangement of the lost-motion connections is such that the respective coil springs are rendered operative only in single but opposite directions of rotation; and the spiral springs, which are supplied with tension adjustment means as before, may be set to release their clutches at the same or different overloads.