Patent GB-457976-A (GB)
Title: Improvements in automatic change speed mechanism
IPC: F16H61/02
Filed: 1935-06-05
Abstract: 457,976. Change -speed gearing. BENDIX AVIATION CORPORATION, 105, West Adams Street, Chicago, U.S.A. June 5, 1935, No. 16358. Convention date, June 6, 1934. Addition to 422,189. [Class 80 (ii)] Relates to automatic speed-responsive changespeed gearing having high, middle, and low gears, the middle and low gear trains including overrunning clutches 61, 73, Fig. 1, the former of which is held inoperative when the low gear is operative. The direct-driving clutch 13 is fitted with cams 31, 34, Fig. 10, with balls 33 between, which disengage the clutch fully when the plates 16 slip. The clutch 13 is held engaged by engaging-springs 26 which press left of Fig. 1 upon a presser plate 22 which carries the ring cam 31 which thus turns with a clutch barrel 17 fast on a driven shaft 18. The mating cam 34 is connected to an engine shaft 10 only when a clutch cone 39 is thrust right to engage a cone 44 against springs 41 by thrust in through pins 42. This thrust is supplied when a spring 59, Fig. 2, is compressed by a slight depression of the accelerator pedal 50 of a vehicle driven by the gearing, and is transmitted through a yoke 49. A positive clutch 92 connects the driven shaft 18 to a propeller shaft 93 for forward automatic drives. Centrifugal weights 23 carried by the barrel 17 act to engage the clutch 13. Further centrifugal weights 27 also on the barrel 17 act to thrust right against a spring 68 a screwed sleeve 64 which, in turning on a screwed boss 158 of the middle speed gear 55, turns a cage 62 clockwise of Fig. 5 to cause the grip rollers 61 of the middle speed overrunning clutch to be operative. What holds the rollers 61 inoperative on the low speed is a cam 76, Fig. 12, rigid with the gear 55 and a cam 78, Fig. 11, connected to the shaft 18 by a spring 81 which expands when the gear 55 overruns so that balls 84, Fig. 1, act through thrust pins 86 to hold the sleeve 64 at left and the cage 62, Fig. 5, turned to hold out the rollers 61. On starting from rest with a slight accelerator depression, since the engine is running slowly, the clutch 13 will slip and become fully disengaged by the cams 31, 34, and since the one-way clutch 61 is held out by the cams 76, 78, the vehicle will proceed on low gear with a pair 112, 71 operative. As the vehicle gains speed, after a momentary release of the accelerator 50 to disable the cams 76, 78, the weights 27 fly out and turn the sleeve 64 on its screw, which is not a torque screw, so as to free the one-way rollers 61 which pick up the drive on middle speed, a pair 154, 55 being operative. As the vehicle gains further speed, a further momentary complete release is given to the accelerator which opens the small clutch 39, 44 and so disables the main clutch opening cams 31, 34 by causing the latter cam to overrun. The plate clutch springs 26 then engage the clutch 13. The cam mechanism 31, 34 thus permits the plate clutch to engage when the shaft 18 overruns the shaft 10. When the throttle is now opened, the weights 23 fly out and the shaft 18 is driven at engine speed with both clutches 61, 73 overrunning. As the load increases, the weights 23 press less hard on the plate clutch, which slips, so that the cams 31, 34 disengage it allowing the middle speed to pick up on the clutch 61, the accelerator being held moderately depressed. If the load increases further and it is desired to change down, the accelerator 50 is fully released. This causes the weights 27 to collapse, the spring 68 expanding, so that the cage 62 turns to throw out the clutch 61. On opening the throttle, the gear 55 is driven faster than the shaft 18 and the cams 76, 78 are forced apart to hold the sleeve 64 in the position of Fig. 1 with the clutch 61 inoperative, whereupon the drive is picked up by the clutch 73 on low speed. A complete release of the accelerator at any time disables the cams 31, 34 so that the plate clutch and high speed are brought in by the springs 26. A full depression of the accelerator, by producing a positive and strong thrust in the pins 42, disengages the plate clutch at any time to bring in middle speed. A positive low speed which enables the engine to be used as a brake is brought in from a lever 102, Fig. 2, by sliding the dog clutch 92 right of Fig. 1 to disengage a member 104 on the shaft 18 and engage a dog member 105 on a loose gear 106 so that the drive passes to the propeller shaft 93 through a pair 107, 106. Reversed drive is through a pinion 1081 and a movable idler 108.