Patent GB-524883-A (GB)
Title: Improvements in or relating to variable-speed power transmission gearing
IPC: F16H47/06
Filed: 1939-02-09
Abstract: 524,883. Variable-speed gearing. SINCLAIR, H. Feb. 9, 1939, No. 4339. [Class 80 (ii)] [Also in Group XXXI] In a power-transmission mechanism, particularly for motor vehicles, comprising a change-speed gear having a high-speed gearselecting clutch 31 of the type which resists disengagement when transmitting torque, and means capable of establishing a lower speed ratio without necessarily interrupting the transmission outside the change-speed gear, the engine accelerator 78 or equivalent control member is connected by a resilient link 81 to a member 73 controlling the disengagement of the clutch 31 and is adapted, when displaced in the direction causing increase of power output and when the clutch is in engagement, to deform the link 81 and bias the clutch towards disengagement, and also to reduce or interrupt momentarily the power output of the engine by interrupting ignition, closing an air throttle, or interrupting fuel injection. As shown in Fig. 1, the engine 10 is connected by a hydraulic turbo coupling 11 and a two-speed planetary underdrive gear 12 to a main gear 13 giving a number of forward speeds and a reverse. The gear 13 may be a selfshifting synchronizing gear as described in Specifications 486,589 and 513,974. The coupling 11, of the Vulcan-Sinclair traction type, has an impeller 14 connected to the engine. shaft by a flexible diaphragm 17 and a spherical spigot 18 as in Specification 510,270, and a runner 15 connected to the input shaft 16 of the gear 12. The annulus 19 of the gear 12, Fig. 2, is mounted on the shaft 16, the planet carrier 22 is fixed on the driven shaft 20, and the sun wheel is formed on a sleeve 25 helically splined to carry a nut 27 movable between a stop 28 and a governor carrier 29 mounted on the sleeve 25. Teeth 31 on the flange of the nut are adapted to engage a toothed ring 32 on the planet carrier 22 or a toothed ring 33 on the drum 34 of a brake arranged as in Specification 510,354. Spring- biassed pawls 35, 36 facilitate the engagement of the teeth, as in Specification 486,589. The brake band 43 is actuated from a pedal 49, Fig. 1, through a flexible cable 53. The governor carrier 29 comprises a disc 56 carrying pivoted governor weights 63 for effecting axial movement of a locking sleeve 59 splined on the nut 27 and having staggered sets of teeth 60, 61 for engagement with teeth 58 on a tubular extension of the disc 56. One set of teeth can be brought into engagement only in the forward position of the nut and the other in the rearward position. For overriding the governor control of the locking sleeve 59, a striking fork 73 on a shaft 74 engages an abutment surface 72 on the sleeve. The shaft 74 carries a lever 75. Fig. 1, actuated from the accelerator pedal 78 through a lever 80, a normally-contracted spring link 81, and a pin- and-slot connection 86, 76. The lever 75 is also connected by a slotted link 103 to the low-speed locking lever 100 of the main gear 13. A lever 94 rigid with the accelerator pedal is connected to the carburetter throttle 96 by a normally contracted spring link 95. In operation, the gear 13 being in neutral and the lever 100 in the position shown in Fig. 1, the engine is started and the shaft 16 rotated idly through the coupling 11. The planet carrier 22 is held by friction in the gear 13 and backward rotation of the sun 24 engages the nut teeth 31 with the brake-drum teeth 33. putting the gear 12 in low speed. The pedal 49 is next depressed to disengage the brake band 43, allowing the sun 24 to rotate idly backwards, and a gear is engaged in the main gear 13. The brake is re-engaged, bringing the gear elements to rest, and the hydraulic coupling 11 slips until the accelerator pedal is depressed. When the speed in the input shaft is sufficient, a change to direct drive in the gear 12 is effected by temporarily releasing the accelerator pedal. The fall in speed of the shaft 16 causes the sun 24 to be set in forward rotation, so that the nut 27 is disengaged from the teeth 33 of the brake drum and is engaged with the teeth 32 by the action of the governor weights 63, the teeth 60 of the locking sleeve 59 also coming into engagement with the teeth 58 of the governor carrier. When the vehicle is running at a speed below a critical value, the sleeve 59 moves to the rear and the gear 12 reverts to low-speed ratio whenever the vehicle comes to rest. If the vehicle is running at a higher speed, the gear 12 can be brought to low speed by depressing the accelerator pedal beyond full-throttle position, extending the spring link 81 and breaking the ignition circuit at contacts 87, 88. The torque load on the sleeve 59 then vanishes and the sleeve is moved to the position shown in Fig. 2, by the fork 73 under the influence' of the spring 83 of the link 81. The contacts 87, 88 then re-engage and the acceleration of the engine brings the teeth 31 from the teeth 32 to the teeth 33 of the brake drum. In this low-gear position, the lever 100 can be brought to its rear position, causing the sleeve 59 to lock the gear 12 in low-speed condition. The gear 12 may be used with a main friction clutch and a main synchromesh gear, the toothed ring on the brake drum being replaced by a fixed toothed ring. In a modification, Fig. 5, the gear units 12, 13 are replaced by a change-speed mechanism including a torqueassisted friction clutch 110 similar to the clutch described in Specification 508,088. A striking fork 115 on a shaft 116 serves to disengage the clutch. The input shaft 114 is rigid with a 26- tooth double-helical gear wheel 117 in constant mesh with a 33-tooth wheel 118 splined to a hollow countershaft 119. On the hub 120 of the wheel 118 is journalled at 26-tooth wheel 121 keyed to a 28-tooth double-helical wheel 122 in constant mesh with a 31-tooth wheel 123 journalled on the shaft 114. A sleeve 124 slidably splined on the countershaft 119 is rigid. with a 22-tooth wheel 125 and a 17-tooth wheel 126, and has jaw-clutch teeth 127 for engagement with teeth 128 on the wheel 121. A slidable gear cluster 129 ... 132 is journalled on a fixed pin 133. A driven shaft 135 is journalled at 136 in the shaft 114 and carries a 42-tooth gear wheel 138 and the tubular hub 140 of a drum 141. A self-shifting synchronizing coupling comprises a nut 142 engaging helical splines 143 on the shaft 135 and having teeth 145 on its flange engageable with teeth 148 in the end of the shaft 114 or with teeth 149 in an extension of the wheel 123. A governor comprises balls 154 in pockets 156 in a member slidable on the hub 140 and yieldingly connected to a locking sleeve 150 splined on the nut 142. A fork 163 engaging an abutment surface on the sleeve 150 is fixed to a shaft 164 carrying a lever 75A corresponding to the lever 75, Fig. 1. The control mechanism for the sliding gears comprises selectors 166, 167, Figs. 6 and 8, slidable on pins 168, 169 and carrying yokes 170, 171, engaging grooves in the gear clusters 125, 126 and 129 ... 132. The selectors are displaced on either side of the neutral position by a gear lever 174 provided with a hand grip 177 connected by a cable 178 to an arm 179 on the friction-clutch actuating shaft 116. In operation, starting from neutral with the engine idling, the friction clutch 110 is disengaged by means of the hand grip 177, allowing the shaft 114 to come to rest, assisted by the friction of the clutch throwout bearing. The gear lever 174 is moved to shift the selector 167 to the " normal low " position N1, shifting the gears 129 ... 132 to engage 129, 130 respectively with 121, 125, and the clutch 110 is allowed to engage. The nut 142 is drawn to the rear and teeth 145, 149 engaged. The change to second speed is effected by shutting the throttle, causing the nut 142 to move to the disengaged position, and moving the gear lever 174 to the position in which the selector 167 is restored to neutral position N and 166 is in position M ; the clutch teeth 127, 128 are thus meshed and the teeth 145, 149 again come into engagement. The change to high speed is effected, if the vehicle speed is high enough for the governor balls 154 to urge the locking sleeve 150 to the left against springs 158, by closing the throttle to allow the nut 142 to move its teeth 145 into engagement with the teeth 148. The locking sleeve 150 is then snapped by springs 162 into the position of engagement of teeth 152, 153 and the gear remains in direct drive until the accelerator is released when the speed is low enough to allow the governor to revert to its initial condition, or until the accelerator is depressed beyond its normal full-power position, to force the change down as described with reference to Fig. 1. In a further form, Fig. 9, the speed-responsive device is omitted and the locking sleeve 150 is biassed by springs 190 towards its direct-drive position. The lever 75B is provided with an additional pin 192 engaging a slot 193 in a link 194 actuated by a cam 196 rigid with a lever 197, which is displaced by the vehicle brake pedal 200 or the hand-brake lever 201. Operation of either brake moves the locking sleeve 150 to the disengaged position.