Patent GB-781396-A (GB)
Title: Improvements in or relating to a variable friction gear
IPC: F16H15/14
Filed: 1955-08-04
Abstract: 781,396. Variable-speed gearing. BEIER, J. Aug. 4, 1955, No. 22509/55. Class 80 (2). In variable-speed gearing comprising friction discs splined on a shaft 1 and interleaved with friction discs splined on a shaft 2, which is movable parallel to shaft 1 so as to vary the degree of interleaving, two gears 3, 4 of different diameters mesh with a gear 5, which continuously engages a gear 41 on shaft 2, so that by rendering the gears 3, 4 alternatively effective two different speed ranges are obtained. The discs on shaft 1 are urged towards each other by a spring 29, which may be assisted by a loadresponsive camming device 52, 72, Fig. 16. In the form shown in Fig. 1, shaft 1 drives, each of a number of shafts 2 is mounted in an arm 31 pivoted on a pin 33 in the fixed casing 7 and connected by a link 36 to a common ring 35 adapted to be rotated in the casing, so as to swing the arms 31, by screw-and-nut means 37, 38 and a link 39, gears 5 are journalled on the pins 33, and the driven shaft 6 is alternatively connected to the gear annulus 3 or to the gear 4 by a toothed clutch member 8 slidable on shaft 6 under the control of a handle 10 on a spindle 42. If member 8 couples annulus 3 to shaft 6, the latter is driven forwardly in a low-speed range, while if member 8 couples gear 4 to shaft 6, the latter is driven reversely in a high-speed range. If shaft 1 is driven by an electric motor, means may be provided for reversing the motor as member.8 is moved from one position to the other, so that shaft 6 is driven always in the same direction. Thus, the motor circuit may include a pair of switches, one or other of which is closed at either of the two operative positions of handle 10, the circuit also including reversing relays and a four-position manual switch. In two positions of the latter, shaft 16 rotates always either forwardly or reversely, while in the other two positions the two speed ranges of shaft 6 are forwardly and reversely or reversely and forwardly respectively. In the epicyclic form shown in Figs. 16, 20, shaft 6 drives and has secured thereto a drum 57 carrying the pins 33 for the mounting of the gears 5 and of the arms 31 carrying the shafts 2. Reverse rotation of the annulus 3 is prevented by a one-way band brake 13, while the sun gear 4 is adapted to be held by a disc brake 14 manually operable by a spring-loaded pin 15. Pins on the arms 31 engage in radial slots in a freely-mounted U- shaped ring 64 which also has cam slots 77 engaged by rollers 74 on spring-retracted bars 59 movable outwards under centrifugal action in radial guides in drum 57 and carrying clutch shoes 60 at their outer ends. With shaft 6 idling, shaft 1 stationary and brake 14 disengaged, members 59 are retracted and, through ring 64, maintain arms 31 in their outermost position, in which annulus 3 turns freely forwardly. As shaft 6 is accelerated and the arms 31 move inwards under the centrifugal action of the members 59 assisted by counterweights on the arms 31, annulus 3 slows down and is finally arrested by the one-way brake 13. Shaft 1 is then driven forwardly in the lowspeed range, the speed ratio increasing with input speed. When the speed ratio approaches unity, the arms 31 being then in their inmost position, the clutch shoes 60 engage the annulus 3 and direct drive ensures. If now the disc brake 14 is engaged by depressing the pin 15, which at the same time forcibly moves the clutch shoes 60 away from the annulus 3 by a coned member 81, shaft 1 rotates forwardly in the high-speed range faster than shaft 6, the speed ratio increasing as input speed decreases. If, with shaft 6 idling and shaft 1 stationary, the brake 13 is tightened manually to give bidirectional braking of the annulus 3, shaft 1 will be driven reversely at a speed which will decrease as the speed of shaft 6 rises.