GB412045A - Improvements in variable speed transmission mechanism for automobiles - Google Patents

Abstract

412,045. Change - speed gearing. BENDIX AVIATION CORPORATION, 105, West Adams Street, Chicago, U.S.A. July 14, 1933, No. 19986. Convention date, Dec. 8, 1932. [Class 80 (ii).] In automatic change-speed gearing comprising a friction clutch 17, Fig. 1, for direct drive, and middle and low speed gear trains each comprising an over-running clutch, cam mechanism 76, 77, Fig. 6, responsive to differential rotation positively disengages the friction clutch when the low-speed train is operative. The middle speed overrunning clutch 44, Fig. 2, is double-acting and a device 153, Fig. 1, is provided for muzzling centrifugal weights 21, 22 to effect a middle-speed drive which is positive in the sense that the automatic operation is cut out and the drive allows using the engine of a vehicle as a brake. A countershaft 109 driven from a driving-shaft 10 drives a middle-speed gear 41 and a low-speed gear 101 both encircling a driven shaft 34, which is shown in Fig. 1 connected by a clutch 128 to a propeller shaft 121. The low-speed overrunning clutch 103 is conventional. The centrifugal weights which are pivoted at 23 on a carrier fast on the shaft 34 have heels 28 which bear on a resilient presser plate 27 of the plate friction clutch 17. The weights also have toes 62. Some of the weights such as 22 are thrust out by springs 64, and their toes 62 act only upon a flange 71 on the end of a screwed sleeve 61 which is splined on the shaft 34 and which receives the torque from the gear 41 on middle speed. The toes of other weights 21 engage the flange 71 and also the end of a sleeve 54 screwed to the cage 51 of the middle-speed clutch 44, so that longitudinal displacement of the sleeve shifts the rollers 44, Fig. 2, between two grip inclines 47, 48 adapted for one-way driving in opposite directions. When the sleeve 54 is moved to the left of Fig. 1 by its spring 56, the rollers 44 engage the inclines 47, and the gear 41 may overrun the shaft 34 but the shaft may drive the gear ; when the sleeve 54 is moved by the weights 21, 22 to the right to the position shown, the rollers 44 engage the inclines 48, and the shaft 34 may overrun the gear 41, but the gear may drive the shaft. The drive is from the gear 41 to a boss 46 integral with a nut 59 upon the splined screw 61. The cam mechanism 76, 77 is inside the boss 46. In a position of rest, the spring 56 has moved the sleeve 54 so that the gear 41 cannot pass on the drive. On the shaft 10 being driven at moderate speed, the shaft 34 is driven at low speed from the gear 101 through the clutch 103. The gear 41 turns loosely at a greater speed carrying with it, by castellations 78, Fig. 4, the cam ring 76. Relative movement causes a spring ring 94, Fig. 5, to expand and retard the cam ring 77. The interposed balls 83, Fig. 6, then thrust the ring 77 to the left of Fig. 1, which thrust is passed on by the splined screw 61 to the toes 62 of the weights 21, 22, which are thus depressed so that the plate clutch 17 is held disengaged. If the operator believes that middle speed may be engaged, the accelerator pedal 151, Fig. 7, is momentarily released to close the throttle 152. The speed of the gear 41 is reduced below that of the shaft 34 and the cam rings 77, 76 return to the position of Fig. 6. The weights 21 fly out to thrust the sleeve 54 to the right of Fig. 1 so that the clutch 44 picks up the middle-speed drive. This drive is passed on to the splined screw 61, which moves to the left so as to depress the weights 21, 22 and hold the plate clutch 17 disengaged. If the load decreases sufficiently, the engine gains in speed and the weights 21, 22 fly out, engaging the direct driving clutch 17, the clutch 44 then overrunning. If the load increases, the clutch 17 slips and the middle-speed clutch 44 picks up the drive so that the splined screw 61, sliding leftwardly, depresses the weights 21, 22 and so fully disengages the plate clutch. If the load increases farther and the operator wishes to engage low speed, he momentarily releases the pedal 151, closing the throttle, whereupon the car momentarily drives the engine, so unloading the gear 41 and permitting the sleeve 54 to move left against the depressed weights 21, so disengaging the middle-speed clutch 44 and allowing the gear 41 to overrun. Upon reopening the throttle, the action is the same as starting from rest. To disconnect the drive, the clutch 128 is moved rightwardly by operating a slide bar 129. Reversed drive is effected through the counter-shaft 109 by moving the clutch 128 farther so as to bring gear teeth upon it into mesh with an idler 118. To effect that the engine may be used as a brake on a positive middle speed, the spring 56 must be allowed to assert itself to turn the roller cage 51. To this end, the obstructing toes 62 of the weights 21 are moved away by collapsing the weights by moving over them a muzzling sleeve 153 to the position of Fig. 8. This sleeve 153 is operated through a slide bar 158 and lever 163, Fig. 7, from a double-acting piston servomotor 169. In the position shown, a slide valve 188 connects ducts 187, 181 so that suction in the engine manifold 186 is passed on to the right side of the piston 173, the muzzle sleeve 153 is at left, and the weights 21, 22 are free to expand. When a preselector button 192 is pulled out, the suction is passed as far as a ball valve 178, the subsequent raising of which allows the suction to pass to the left side of the piston 173, causing the muzzling of the weights 21, 22. This raising of the ball 178 is effected by depressing either the accelerator pedal 151 or the engine clutch pedal 244. To this end, these pedals are connected by bell cranks 208, 218 to pins working in slots 204, 205 in a link 203 connected by a lever 198 to a rod 197. As the rod 203 is thrust down against a spring 201, the rod 197 engages and strikes up the ball 178, opening the passage for the vacuum. Thus power is brought in by depressing either control pedal to muzzle the speedcontrolling weights and so cut out the automatic speed-change and establish a fixed drive for braking by the engine or for hill climbing.