GB843143A - Improvements in or relating to shaft couplings - Google Patents

Abstract

843,143. Positive clutches. ELLIOTT BROTHERS (LONDON) Ltd. Sept. 5, 1958 [Sept. 5, 1957], No. 28097/57. Class 80 (2). Driving and driven shafts 7, 31 in an instrument such as a calculator, computor or recording device, can be connected by a dog clutch 32, 33 only when baulking dogs, &c., 23, 36 on rings 19, 34 mounted for rotation upon the driving and driven clutch members 1, 2, and driven through gear trains 21, 24, 22; 38, 39, 37, respectively, are also aligned. In the form shown, the driving clutch member 1 is formed with seventy-one gear teeth 21 and the ring 19 is formed with seventy-two gear teeth 22 of the same pitch circle, these teeth meshing a pinion 24 mounted upon a support 27. Similarly, a driven clutch hub 30 is formed with seventy-one teeth 38 and the ring 34 is formed with seventytwo teeth, the teeth 37, 38 meshing a pinion 39 journalled upon a support 40. If, during a cycle of seventy-two revolutions, the clutch is disengaged, then rotation of either the driving or the driven shaft 7, 31 will cause the associated ring 19, 34 to be turned relatively to the driving or driven clutch member 1, 2, so that re-engagement cannot be effected until the driven or driving shaft has been similarly turned. The driving clutch member 1 comprises a hub 3 connected for rotation with the driving shaft 7 by axial lugs 4 sliding in slots 5 in'a disc 6 fast thereon, a manually operable selector fork 44 having rollers 45 engaging a groove 43 to slide the clutch hub axially against the bias of a spring 12 to its disengaged position. Fast upon the clutch hub 3 is a ring 9 having axial lugs 14 projecting into slots 15 in an Oldhamtype coupling disc 16, radial pins 17 in the lugs 14 lying freely in holes 18 in the disc. Slots 33 in the Oldham's disc 16 engage with axial dogs 32 upon a disc 28 fast with the hub 30 secured to the driven shaft 31, and transmit driving torque to the driven shaft. The axial dogs 23 on the baulking ring 19, and the corresponding slots 36 on the baulking ring 34, are of different circumferential lengths, to prevent engagement of the clutch when the parts are 180 degrees out of alignment, the dogs fitting into the slots with play equivalent to one half of the width of a tooth from the gears 37, 38 and 21, 22. As modifications, different numbers of teeth 21, 22; 37, 38 may be provided and the pinions 24, 39 may be double gears.