Patent GB-349164-A (GB)
Title: Improvements in or relating to power transmission couplings
IPC: F16D21/00
Filed: 1930-03-07
Abstract: 349,164. Operating combined friction and positive clutches. SULZER FRERES SOC. ANON., Winterthur, Switzerland. March 7, 1930, No. 7471. Convention date, March 7, 1929. [Class 80 (ii).] An electromagnetic, hydraulic, friction or other slidable coupling is paralleled with a positive clutch which closes with a snap action under the control of two governors actuated by the driving and driven shafts respectively when the driven shaft has attained the desired speed. At least one resilient member such as a spring or rubber buffer is so arranged as to absorb shocks due to operation of the positive coupling. Rotatable with a driving shaft 1 is a drum 10 having interior friction faces 3 engaged to transmit drive to a driven shaft 2 by oppositely moving cheeks 4 axially movable on a drum 9 attached to the driven shaft. The friction clutch is engaged through a linkage by a cam 8 on an operating sleeve 44. The exterior surface of the drum 10 carries positive clutch teeth 11 engaged by rotatable pawls 12 carried in a ring 13 rotatable with a housing 17 fixed to the driven shaft. To absorb shock and torsional oscillations the ring 13 is resiliently mounted in the housing by the provision of springs or rubber blocks 18. The positive clutch is operated through rock-arms 14, links 20, 19, 23 and push-bars 21 from a cam 22 on an operating sleeve 40. The arrangement of links is such that correct movement is transmitted to the pawls independent of relative movement of the ring and casing. A spring 55 and/or a counterweight may act on the lever 19 to counteract centrifugal force. As shown in Fig. 1, the operating gear comprises an electric motor 51 coupled to a pump 49 which generates pressure in a liquid, preferably oil, to act directly on a piston 46 and close the friction clutch. The positive clutch is closed through a servomotor, the supply of pressure fluid to which is controlled jointly by centrifugal governors, one 24 being coupled to the driving shaft by a belt 56, the other 25 to the driven shaft by a belt 57. The governor sleeves operate through a rod 26, a piston valve 27. Initially, with the driving shaft rotating and the driven shaft at rest, the piston valve 27 is tilted into its lowest position b. The motor 51 is then started and the piston 46 closes the friction clutch. The rotation thus imparted to the driven shaft raises the governor 25 and at the desired speed, which may be the synchronous speed, the piston valve is opened; position a. The oil pressure then moves up a piston 32 in a servomotor 31 against a spring 33. When the spring is sufficiently compressed, the piston trips a latch 37 and allows the spring pressure to operate rapidly on a second piston 34 which closes the positive coupling. An adjustable release valve 50 determines the operating pressure of the fluid, the overflow of which may be returned by a pipe 54 to the reservoir 53. Locking means may be provided to prevent engagement of the positive clutch until the speeds of driving and driven shafts are equal, and the friction clutch may be operated manually through a hand-lever connected to rod 44. The pawls 12 may be arranged radially instead of axially. The coupling may be arranged between the motor and pump in hydraulic accumulator apparatus so that the pump whilst under no load can be coupled to the motor whilst it is running. The Specification as open to inspection under Sect. 91 (3) (a) states also that the friction and positive clutch may be operated either individually or jointly by hydraulic or by electromagnetic means and that locking means may be provided to prevent disengagement of either clutch except under predetermined conditions. This subject-matter does not appear in the Specification as accepted.