Patent GB-894005-A (GB)
Title: Improvements relating to transmission shift control mechanisms
IPC: F16H59/10
Filed: 1960-11-10
Abstract: 894,005. Change-speed control. GENERAL MOTORS CORPORATION. Nov. 10, 1960 [Nov. 23, 1959], No. 38604/60. Class 80 (2). Also in Group XXXVII] A ratio-range control mechanism comprises a detent plate rotatable through a lost-motion connection by an actuating lever into any one of a number of positions corresponding to the different ratio ranges of a change-speed gear, a latch arm biased towards the detent plate engaging with notches thereon to lock it in position and a cam surface on the actuating lever being adapted to force the latch arm away from the detent plate during movement of the actuating lever effecting taking-up of the lost-motion. As shown, the ratio-range selector cable 12 of a motor car transmission 16 is fast with a detent plate 40 pivoting on a pin 31 and locked in the various range-selected positions by a spring-biased latch 54, pivoting at 55 and coacting with notches 49 . . . 51 on the detent plate. A spring assembly 64 pivotally connected to the detent plate 40 biases the latter to a central position corresponding to neutral in the transmission. An F.N.R. control knob 42 mounted on the motor car dashboard is connected through links &c. 46 to a lever 24 pivoting about a pin 22 and formed with a cam recess 32 coacting with a pin 39 on the detent plate 40. To establish reverse, the knob 42 is pulled to turn the lever 24 and by engagement of the cam recess 35 with the pin 39, also turn the detent plate 40 and thus pull the cable 12, the latch plate 54 now locking the detent plate and the spring system 64 biasing the latter to return to its neutral position. To return to the neutral position and then establish the forward range of ratios, the knob 42 is pushed to turn the lever 24 anti-clockwise. Lost-motion between the cam recess 35 and the pin 39 allows the edge 60 of the lever 24 to engage a stud 58 on the latch 54 and turn the latter against the bias of its spring to a released position. The neutralizing spring system 64 then restores the neutral position of the parts, and continued pushing of the control knob 42 turns the lever 24 so that the cam recess 35 coacts with the pin 39 to turn the detent plate 40 in the opposite direction to its " forward " position, where it is again locked by the latch 54. To return to the neutral position from the forward position, the knob 42 is pulled and lost-motion between the stud 58 and the cam recess 35 again allows the lever 24 to turn so that its edge 60 once more acts on the stud 58 to release the latch 54. When the knob 42 and the lever 24 are in the " forward " position, a second knob 43 can be pushed to turn a lever 26, Fig. 9, about the pivot-pin 22 and condition the transmission for braking. A recess 38 in the lever 26 engages the pin 39 on the detent plate 40, which is thus turned further until the latch 54 engages the notch 49. To return to the " forward " position, the knob 43 is pulled and lost-motion between the recess 38 and the pin 39 allows the lever 26 to turn so that an edge thereon engages the stud 58 to release the latch 54, the neutralizing spring 64 then returning detent plate 40 to the previous position. Interlocking between the parts prevents movement of the knob 43 &c. except when the knob 42 is in the " forward " position. The knob 43 can alternatively be restored to its " off " position by nudging the knob 42, this acting through the lever 24 and a link 122 to disengage the latch 54. The detent plate 40 can be restored to neutral from any position by actuation of a knob 500 connected to a slide 90 mounted on the pin 31 and slidden against the bias of a spring 96 to engage its end 104, Fig. 3, with the latch 54, thus turned to its released pisition. Movement of the slide 90 also acts through a bellcrank lever 116 of insulating material to close one of the sets of contacts of a double switch 120 to make the circuit through the starter motor of the car. Turning the bell-crank lever 116 in the opposite direction is effected when the lever 24 is pulled to its " reverse " position by coaction of the stud 39 with an arm 118 thereof, to close the other set of contacts and thus make a circuit lighting the reverse lamp. In a modified form, a control handle 200, Fig. 12, has a hole 204 engaging with lostmotion a pin 53 connecting the detent plate 40 to the transmission ratio range selector cable 12, a latch 56<SP>1</SP> co-operating with the detent plate having a stud 58<SP>1</SP> engaged by surfaces on the handle 200 to withdraw the latch from the detent plate as required. A separate transmission parking brake handle 223 slides a link 226 to withdraw a latch 245 from a second detent plate 228, a stud 230 on the link engaging with lost-motion the second detent plate to turn the latter in the brake-engaging direction against spring bias. A parking brake cable 234 is secured to the brake detent plate 228. A lock, Figs. 13, 15 (not shown), may retain the parking brake lever 223 in the " park " position, and is associated with the ignition switch 220 in such a way as to move to the " locked " position when the switch is " off."