Patent GB-443842-A (GB)
Title: Improvements in or relating to change speed mechanism for variable speed gears
IPC: F16H61/02
Filed: 1934-09-06
Abstract: 443,842. Variable-speed gearing. ROESCH, G. H., and TALBOT, Ltd., C., Barlby Road, Ladbroke Grove, London. Sept. 6, 1934, No. 25719. [Class 80 (ii)] A succession of similar movements of the actuating member of the gearengaging and disengaging means effects a succession of changes from bottom gear to top gear, and then a succession of changes backwards and forwards between top gear and the next lower gear, an overriding preselector control enabling, at any time, the preselector mechanism to be so set as to render any of the gear trains engageable when next the actuating member is moved. The gear box comprises a number of trains each of which has a swing link 10 forming a connection between a bus-bar 15 and a brake control member 14. The link is pivoted at 11, Fig. 3, to a member 12 fulcrumed at 13 and adapted to actuate member 14. The links 10 are reciprocated to actuate the brakes by the bus-bar 15 mounted on a lever 16 pivoted at 17. The bus-bar, urged upwardly by a spring (not shown), has a pallet 18 engaged by a lever 19 actuated by a pedal lever 21. The links 10 tend to swing away from the bus-bar, but each is provided with a selector link 22 pivoted at 23 and urged by springs 24 into the path of the bus-bar. The selector links may, however, be kept out of engagement with the swing links by means of cams 26 on shaft 25 which are so arranged that only one selector link at a time may engage a swing link. It is usual to rotate the cam shaft by hand, e.g. through lever 31 and linkage 30 . . 28, to disengage the selector link in operation and bring in another for the next gear to be engaged. Then, on depressing the pedal 21, the bus-bar is lowered to disengage the gear in operation, and allow the other swing link to be urged into position to be moved by the bus-bar on its return movement. Specification 422,874 describes means for effecting this automatically from bottom to top gear, and similar means are embodied in the present construction with the additional feature that when top gear has been reached, continued actuation of the pedal produces changes backwards and forwards from top to the next lowest gear. A ratchet wheel 32, with a number of teeth corresponding to the gears, is secured on the cam shaft 25, and is adapted to be engaged by a pawl 33, Fig. 1, pivotally mounted on one arm 35 of a bell-crank lever the other arm 36 of which is connected by telescopic link 38 ... 44 to the lever 19. The bell-crank is supported by pin 45 on an adjustable rod 46 by means of which the engagement of pawl 33 with the ratchet wheel can be varied. Depression of lever 21, causes pawl 33 to sweep past the ratchet teeth, and at the same time swing link 10 is released and the next swing link forced into position. Release of the foot pedal causes pawl 33 on its return movement to engage and rotate the ratchet and cam shaft to free the swing link just engaged and bring a new selector link into engagement. When top gear is reached, the following mechanism comes into action. A pawl 53, Figs. 2, 3, pivoted to a lever 55 is engaged on its under side by a pin 56 on the top gear swing link 10, and the tip of the pawl is adapted to engage the ratchet teeth. The extent of engagement is adjusted by the lever 55 pivoted at 57 to brake member 14 and engaged at its upper end by an adjusting rod 58. When the pedal is depressed, the pin 56 is brought under the pawl 53 and upon release of the pedal, the pawl will rotate the ratchet wheel and cam shaft in a direction the reverse of that imparted to obtain the previous gear. Hence continued depressions of the actuating pedal 21 result in changes backwards and forwards from top to next gear unless the hand control 31 be operated to rotate the camshaft to select a lower gear. Specification 349,825 also is referred to.