Patent GB-1056559-A (GB)
Title: Positive clutch
IPC: F16D11/06
Filed: 1964-09-07
Abstract: 1,056,559. Positive clutch and brake control. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 7, 1964 [Sept. 27, 1963], No. 36626/64. Headings F2C and F2L. To ensure complete tooth/pawl engagement and reduce shock loading in a half revolution positive clutch, wherein a driving member 42 has internal teeth 41 engageable with outwardly spring-biased drive and overrun-preventing pawls 27, 25 pivoted at 24, 23 on a driven member 19, an auxiliary pawl 29 longitudinally slidably connected to the drive pawl 27 and spring biased to project beyond the latter for initial engagement with a driving member tooth has an angled surface 61 on its tip to cam the auxiliary and drive pawls to the next tooth in the event of incomplete tooth/pawl engagement, and the driven member 19 is connected to a load shaft 1 through rubber or resilient plastics. The driving member 42 shown comprises an electric motor-driven toothed belt pulley rotatably mounted on the shaft 1. As shown, the driven member 19 drives the shaft 1 through rubber segments 21, 22 disposed between fingers 20, 7 respectively extending from the driven member 19 and a hub 5 secured to the shaft. Alternatively, the rubber segment could be omitted and the fingers 7 enlarged and formed of resilient plastics. A throw-out ring 17 supported on the driven member 19 comprises latching surfaces 47, 48 co-operating with a latch 49, cam grooves 44, 46 co-operating with pins 32, 45 respectively extending from the pawls 27, 25, and grooves 15, 16 engaging, with lost motion, stops 13, 14 on a collar 8 which is secured to the shaft 1 and comprises cam lobes 10, 11. The latch 49 is pivoted on a resilient support 50 and is pinned to one end of a link 55 which is urged in the unlatching direction by a spring 59 and held in the latching position by a fixed stop 57 engageable behind a shoulder 56 on the link. A spring-biased bell-crank lever 62 comprises a follower roller 65 co-operating with the cam lobes 10, 11 and an arm 66 engageable with the latch 49. Back-running of the shaft 1 is prevented by a latch 69 spring-biased into engagement with a four-toothed ratchet detent wheel 70 secured to the shaft. In operation, assuming the latch 49 is engaging the latching surface 47 as shown in Fig. 3, when the link 55 is downwardly tripped and the latch 49 withdrawn, the pawls 29, 27, 25 spring out into successive engagement with driving member teeth and the shaft 1 is driven. The throw-out member, taking up lost motion in the grooves 15, 16, rotates forwardly slightly relatively to the shaft 1 due to the camming action between the pins 32, 45 and the grooves 44, 46 and then is entrained by said pins to rotate with the driven member 19. The rotating cam lobe 11 acts on the roller 65 to urge the bell-crank lever arm 66 into engagement with the latch 49. The cam lobe shape is such that the latch 49 is inwardly moved beyond its latching position moving the link, against the spring 59, to dispose its shoulder 56 behind the stop 57, and then the latch is moved back to its latching position where, when the roller 65 drops off the cam lobe, it is retained by the stop 57 and the spring 59. When the latch is abutted by the latching surface 48, the throw-out ring is stopped, the pins 32, 45 ride down the grooves 44, 46 to disengage the pawls and the lost motion in the grooves 15, 16 is taken up, this time by rotation of the driven member 19. The resilient support 50 for the latch 49, absorbing latching shock, permits slight overthrow of the shaft on stopping. The two pairs of diametrically opposed teeth of the ratchet detent wheel 70 respectively prevent reverse rotation of the shaft after said overthrow and oscillation of the clutch after the roller 65 reaches the highest dwell of the lobes 10, 11.