GB337033A - Variable speed gears - Google Patents

Abstract

337,033. Denman, W. July 25, 1929. Clutches, c l a w ; operating clutches.- A clutch more particularly for use in motor-car variablespeed and reversing gearing comprises an arrangement of helically winged pawls pivoted into engagement with a toothed ratchet wheel by axial movement of a rotatable ring having helical slots engaging said wings. As shown in Fig. 3, attached to the driven shaft 4 is a boss carrying ratchet teeth 6 engaged by pawls 7 pivoted on pins 8 to a bossed drum 5 keyed to the driving shaft. Two pairs of pawls, each pair engaging oppositely directed ratchets to give a reverse drive, are used and each pawl has an integral helical wing 9 engaging a helical slot in a cylindrical ring 11 feathered to the drum 5 and having a flange 12 running between grooved rollers 20 on an operating frame 15. This frame carries pins 17, Fig. 7, guided by oblique cam slots in fixed members 19 so that by pushing on a rod 31 the frame is given a helical motion which communicates through the rollers 20 an axial motion to the ring 11 to pivot the pawls into engagement. For each pair of pawls the wings with their slots are oppositely inclined so that each pair is pressed into or lifted out of engagement by movement of the ring 11. In the constant mesh countershaft variable-speed and reversing gear shown in Fig. 7, the larger of a pair of meshing wheels, indicated by chain lines 42, is mounted freely on. its shaft and is recessed to form a grooved boss carrying the ratchet teeth 6. The pawl-carrying boss 5 is keyed to the shaft and the wheel is clutched to the shaft to give the required speed by operation of the appropriate frame 15. For operating the frame there is shown a push button mounted in a fixed frame and universally jointed to the rod 31. A blade spring locking catch retains the button in the engaged position of the clutch and it is spring returned to the disengaged position on release of the catch. In the speed gear this catch is modified and comprises a spring- loaded member 44 adapted to lie behind and prevent return movement of a cam 45 on the frame 15 when this has been operated to engage the clutch. The catches for the clutches on each shaft are mounted on a shaft 43, and on a parallel shaft linked to it, so that when any one frame is operated all the others are freed. The catches may also be freed by hand or pedal through a rod 48. In a simple form for clutching a loose pulley to a shaft the operating frame is dispensed with and the ring 11 is directly operated by a fork engaging a groove in a sleevelike axial extension of the ring feathered to a similar extension of the pawl-carrying drum 5. The clutch is housed within the overhanging pulley rim. In another form only a single set of pawls and a single ratchet wheel are used. According to the Provisional Specification operation of the catch rod 48 by hand, foot, or knee gives a free engine and a free wheel, and the pawls may be held in position partly by spring means.