Patent GB-653637-A (GB)
Title: Improvements in or relating to variable speed power transmission
IPC: B60W30/18
Filed: 1948-02-06
Abstract: 653,637. Change-speed gear. CHRYSLER CORPORATION. Feb. 6, 1948, No. 3511. Convention date, Nov. 28, 1940. [Class 80(iii)] A single-stroke pneumatic motor, Fig. 11, for operating a dog-clutch F in a vehicle change-speed gear, comprises a reciprocatory tubular piston-rod 76<SP>1</SP>, sliding on a fixed central guide-post 78 and secured to a spring-loaded single-acting diaphragm 76, which also co-operates with an electromagnet 79 which, when energized, attracts at its rear end (right. Fig. 11), an armature 92 opening a valve 95, supplying enginesuction to the rear face of the diaphragm to move it to its rear end position, and also attracts at its front end a second armature 91 secured to the diaphragm 76 for holding the latter in its rear end position independently of engine-suction and in opposition to the diaphragm return-spring 90. The electromagnetic winding 79 is arranged between concentric cylindrical core members 80, 82, provided at their front end with a magnetic shunt-ring 88 and at their rear with non-ferrous mounting-rings 83, 84. The valve-armature 92 is carried on a sliding plunger 86 and, when attracted by the electromagnet in opposition to a returnspring 87, moves the valve 95 forwards through a yielding spring 96 to open the diaphragm-space to the suction inlet pipe 99 and close an exhaust seat 103. General system. The four forward speeds of a countershaft-gear, Fig. 3, are controlled by two balked synchromeshed clutches, one 42 of which, a manually-controlled double clutch, selects either of two ratio-ranges in which the other F of which a single clutch power-operated as above described, automatically selects between a freewheeling third and bi-directional fourthspeed in one range, and between a freewheeling first and bi-directional second in the other. A countershaft-driven centrifugal governor and accelerator kickdown shift, accompanied by ignition disablement, control the automatic shift, which is executed electropneumatically. The gear is driven through a fluid-coupling and a conventional pedal-operated friction clutch. Gear details. In its rearward position the manual clutch-sleeve 42 clutches to the output shaft 20 a wheel 39 which is then, in the disengaged position (shown) of the automatic clutch F, driven in free-wheeling first-speed from the input shaft 27 through wheel-pair 28, 34, one-way roller clutch E and wheel-pair 36, 39. The automatic clutch F, in its forward engaged position, clutches the input wheel 28 to a freely mounted wheel 40 so that the countershaft is now driven at a higher speed through the wheelpair 40, 37 with overrun in the rollerclutch E. With drive through the wheelpair 36, 39 this gives bi-directional second speed. In its forward position the manual clutch-sleeve clutches the wheel 40 to the output shaft 20, and the same two positions of the automatic clutch F give respectively a free-wheeling third speed through wheelpairs 28, 34; 37, 40, including the rollerclutch E, and bi-directional fourth speed, which is direct. Synchromeshed clutch. The internal teeth of the automatic clutch-sleeve F, which slide on splines 48, Fig. 5, on the hub of the wheel 40, are alternately long 50, and short 51, and some of them may be bridged as shown. Balk-teeth 53 are carried on a friction cone 52. which has circumferential play relative to the driven wheel 40 and is constantly spring-loaded onto the driving wheel 28. During a normal upshift in the driving condition when the driving wheel 28 has to be decelerated for synchronism, the short teeth 51 are balked by the balk-teeth 53 so that on synchronism the teeth 50, 51 pass directly through the balk-teeth to engage the clutch-teeth 49 on the driving wheel 28. If however the shift is made on coast-load, the balk-teeth 53 are at the opposite limit of their circumferential play on the driven wheel 40 and thus obstruct the long teeth 50 first, so that when the driver is accelerated to and beyond synchronism unbalking of the long teeth 50 is followed by balking of the short teeth 51. This is to ensure that final synchronism must be produced by deceleration of the driver rather than by acceleration alone, and avoids shock which might occur in the latter case. Selector control. The selector fork 60 of the automatic clutch-sleeve F, is turned on a fixed spindle 59 by a three armed lever 67, Fig. 11. which turns with a rock-shaft 66, one arm 65 being slotted to engage a pin 63 on the selector-fork 60 by which the lever 67 turns the fork. A tension-spring 58 links the other lever arm 68 to the fixed pivot 59, and the arrangement is such that when the actuating piston-rod 76<SP>1</SP> of the suction-motor above-described moves to its extreme forward (left) position shown, the lever 67 rigidly turns the selector-fork 60 clockwise to move the clutch-sleeve F positively to its rear disengaged position, whilst during rearward engaging movement of the piston-rod 76<SP>1</SP>. the clutchsleeve F is detained in a balked position, so that the piston-rod 76<SP>1</SP> separates from the adjustable button 69 of the lever-arm 67, leaving the spring 58 to complete the forward engaging movement of the clutchsleeve F and restore contact between the button 69 and the piston-rod 761. Electric circuit. Battery current, supplied through the usual ignition switch 0 to the magnet winding 79 completes an earthcircuit through a normally closed accelerator-kickdown switch P in series with an initially open centrifugal-governor switch M, driven by a countershaft-wheel 130. Attainment of a pre-determined vehiclespeed, 7 m.p.h. in first speed and 15 m.p.h. in third, closes the governor-switch M, energizing the magnet-winding 79, to supply suction to the diaphragm 76 which immediately moves fully to the rear, leaving the lever 67 and selector-fork 60 in a balked position, biassed by the spring 58. In this condition, momentary release of the accelerator-pedal by the driver creates overrun which synchronises the clutch F which is then engaged by the spring 58, giving either second or fourth speed depending on the range previously selected by the manual clutch 42. On deceleration the governor-switch M breaks the upshift circuit at vehicle speeds of 7 m.p.h. in direct drive and 3 m.p.h. in second-speed. causing downshift to occur when the coast load becomes low enough to permit the dogclutch F to be disengaged by the now free diaphragm-spring 90. Kickdown. Full depression of the acelerator-pedal 50<SP>1</SP> above the governor-speed opens the switch P, breaking the circuit of the winding 79, which causes closure of the valve 95, venting the diaphragm 76 which is then loaded by its spring 90 for forward movement. In addition to closing the suction-valve 95, the released magnetarmature 92, in its rearward movement, also, through a plunger and spring 122, closes an earthed switch K, in series with another switch L, at this time also closed by a plunger 125 and spring 124 compressed by the diaphragm in its rearmost position. The simultaneous closure of the two switches K, L earths the live terminal 128 of the engine ignition distributer 129, thus temporarily cutting out the engine ignition, causing torque-reversal which unloads the clutch-sleeve F, permitting the diaphragm-spring 90 to move the diaphragm 76 to its fully forward position, disengaging the clutch F to allow the overrunning clutch E to pick-up first or third speed depending on the range manually selected. During the forward movement of the diaphragm, the spring 124 expands, permitting the switch L to be opened by a torsion-spring, thus breaking the interrupter-circuit and restoring the ignition, which may be arranged to occur either before or after the clutch F disengages.