Patent GB-684833-A (GB)
Title: Improvements in or relating to change-speed power transmission
Filed: 1948-02-03
Abstract: 684,833. Change-speed control,; claw clutches. CHRYSLER CORPORATION. Feb. 3, 1948 [Jan. 16. 1941], No. 3134/48. Class 80 (ii). [Also in Group XXXIV] On a motor-vehicle, four ratios, provided by a simple countershaft-gear unit 83-93, Fig. 9, having two reduced, one reverse ratios and direct-drive, followed by a planetary directoverdrive unit 93-103, are electrically controlled in part by two output-driven governors G, G', Fig. 35, the arrangement being such that, accelerating from rest in a free-wheeling second-speed (overall second-direct) to a predetermined speed (10 m.p.h) causes one governor G<SP>1</SP>, without driver intervention, to make an automatic upshift in the overdrive unit to give an overall third speed, made up of the second countershaft speed and overdrive (overall second - overdrive), whilst, after exceeding a second higher predetermined speed (20 m.p.h.), the other governor G operates to permit an upshift to direct-drive in the countershaft unit, whilst maintaining overdrive in the planetary unit, giving overall direct-overdrive, to be obtained volitionally at any higher speed, only when the driver releases the engine accelerator-pedal to unload the clutch-teeth of the countershaft gear. Also taking part is an accelerator kickdown switch 77 operation of which, at or beyond full throttle, downshifts the planetary unit to give a bidirectional overall third speed, this time made up of direct-drive in both units (overall direct-drive) and lying between the upshift third speed (second-overdrive), and high (direct-overdrive). Automatic downshift occurs at lower speeds. A supervisory manual control is provided by a steering-columnmounted lever 173, Fig. 3, which, in the upper plane of movement provides invariable emergency low and reverse in the usual lever-positions, and in the spring-biased, lower plane gives, in the usual second-speed lever position, a bi-directional second speed subject to one automatic upshift to a bi-directional third speed with kickdown return to bi-directional second, and,.in the usual high-speed lever,position, selects, for starting, a free-wheeling second-speed to be followed by the automatic and semi-automatic upshifts as above described. After preliminary operation of the usual vehicle clutch-pedal 84, Fig. 35, to reach this lever-position, no further operation of the clutch-pedal or shift-lever is necessary in driving, stopping or starting, the gear being driven through a fluid-coupling in series with the conventional pedal-controlled friction disc-clutch. Shaft arrangement. The gearing, Fig. 9, comprises an input shaft 83 driving through the three-speed and reverse countershaft gear an aligned intermediate shaft 93 which drives the aligned final output shaft 103 through the direct-overdrive planetary unit. Countershaft gear. Emergency low and reverse are by the usual sliding wheel 119 with shift-yoke 120, whilst second and high (directdrive) are introduced by a sliding double toothed clutch-sleeve Q, having coned friction synchronising rings 114 with balk-teeth. In addition to its neutral and bi-directional second- and high-speed positions, this clutch-sleeve Q has a fourth position, between neutral and high, in which neither second or high speed clutch-teeth 110, 101 are engaged, but the sleeve frees for engagement the cage 121 of a one-way roller clutch F between the freely mounted second-speed wheel 109 and the clutch-hub 104 fast on the shaft 93, thus providing free-wheeling second-speed in which the vehicle is normally started. The functioning of this clutch forms the subject-matter of divided Specification 684,892 and is also described below. Planetary overdrive unit. The planet-carrier 212, fast on the intermediate shaft 93 (input for the planet-gear), is clutched to the freely-mounted reaction sun 216 for direct-drive by clutch-teeth 228 on the end of a sleeve 226, splined to the sun, and carrying two splined brake-discs 230 for interleaved engagement with three non-rotary dises 233, all being clamped together forwardly to engage the brake for overdrive, by fluid-pressure acting on an annular piston 240, the forward axial movement of which causes the adjacent end brakedisc 230, backed by a snap-ring 231, to take axially along with it the splined sleeve 226, thus disengaging the direct-drive clutch-teeth 228. At the commencement of this movement, initial engagement of the two rear brake-discs unloads the clutch-teeth and splines of the sleeve 226. The output ring-gear 217 is secured to the final output shaft 103 and both overdrive and direct-drive are bi-directional in the planetary unit. The direct-drive clutch-teeth 228 are of the Maybach type, engaging under spring- load 248, 249 on exhausting the brake-piston 240, and, to provide instant drive take-up if the teeth 228 do not immediately mesh, a one-way forward-driving roller clutch H is arranged directly between the input carrier 212 and the output ring-gear 217. The brake-discs 230, 233 are all interspaced in definite axial positions with clearance when disengaged, by groups of independent springs 248, 249 for the inner discs 230 and 236, 237, Fig. 9B, for the radially-projecting ears 234 of the outer discs 233 which slide non-rotatively in axial recesses 235 in. the fixed casing. Flanged abutment sleeves 251 position the inner discs 230, and similar sleeves 239, together with headed pins 238 position the outer discs 233. Mechanical selective control. The inner end of the manual shift-lever 173, Fig. 3, is forked for pivotal connection 188 with a shift-tube 184 surrounding the rotatable steering shaft 182. Vertical cross-shift movements of the manual lever 173 fulcrum a lever-enlargement 178 about a slot 180 in the fixed housing 175 below the steering-wheel 183, so as. to cause the shifttube 184 to move axially in the opposite direction and operate through a Bowden cable, Fig. 1 (not shown), a cross-shift lever 169, Fig. 10, which, through a fork 167, slides a sleeve 159 axially along a rockshaft 160 to cause a finger 142, Fig. 14, integral with the sleeve 159 to select notches in either the shift-fork 120 of the low-reverse wheel 119, Fig. 9, or in a sleeve 139, Figs. 12 and 14, which slides freely on the shiftrail 113 to which the fork 112 of the seconddirect clutch-sleeve Q is secured. A spring 165, Fig. 10, biases the finger 142 towards the sleeve 139. The finger-sleeve 159 is turned with the rockshaft 160 to operate the selected shift-member 120 or 139, by turning movement of the shift-lever 173, Fig. 3, which turns the shifttube 184, the lower end of which is linked by rods, Fig. 1 (not shown), to an arm 171, Fig. 10, on the rockshaft. The forward movement (left, Figs. 12 and 14) of the manually operated shift-sleeve 139 serves to take the clutch-yoke 112 from its bi-directional second-speed rearmost position, through neutral, as far forward as free-wheeling second-speed position only, at which point the shift sleeve is arrested by positive stop-pins 144. The final movement in the same direction to the foremost position, for direct-drive, is performed only by fluid-pressure acting on a spring-returned piston 135, Figs. 12 and 35, which acts directly on the shift-rail 113 through an inner spring 146 which allows the clutch-sleeve Q to be detained in a balked position during engagement. This manual and power movement of the sleeve Q forms the subject-matter of Specification 684,894. Electro-hydraulic control. Fluid-pressure for the second-direct clutch-piston 135 and the overdrive brake-piston 240 is supplied by a singlepump P, Figs. 9 and 35, driven by an input countershaft wheel, control being by individual solenoid valves V, V<SP>1</SP> which, with their respective solenoids S, S' de-energised as shown in Fig. 35, are moved by springs 298<SP>1</SP> into the open position supplying pressure to the pistons, whilst in the energised position the valves exhaust the pistons at 288, 292 and springs 138; 248 &c. respectively return the second-direct clutch-sleeve Q to free-wheeling second, and the overdrive unit to direct-drive. Each valve-solenoid S, S' is controlled by a separate centrifugal governor switch G, G', these governors being arranged at opposite ends of a transverse shaft 253, Fig. 9, skew-gear driven by the outputshaft 103, which drives the road-wheels; The governor-switches, described below, break their contacts above a predetermined speed and make them below a predetermined lower speed, each having different speed settings. Start and shift sequence is as follows: - Manual low-reverse start. This requires depression of the clutch-pedal 84, which closes a switch 336, this time without effect, after which the manual shift-lever 173, Fig. 3, is placed in the usual low or reverse position which operates the low-reverse shift-yoke 120 to mesh the sliding wheel 119, Fig. 9, and also causes a hump 317, Figs. 10 and 35, on the yoke to permit a spring-loaded switch 316 to close on leaving neutral in either direction. At this time this switch is without effect since the parallel contacts of the now-collapsed governor-switch G are made, and supply current, switched by the ignition switch 314, to the solenoid S of the valve V thus exhausting the overdrive brake-piston 240 so that the overdrive unit assumes directdrive. The solenoid S' of the valve V<SP>1</SP> is also energised, both through the collapsed governor G' and a switch 326, Figs. 14 and 35, which is broken by the inclined end 329 of the seconddirect shift-rail 113, when the latter moves (to the left of Fig. 35) from neutral to free-wheeling second and high-speed positions only. Both solenoid-valves are therefore maintained energised independently of governor or other action, so that, on release of the clutch-pedal the vehicle starts in and maintains a bi-directional emergency low or reverse (the former 11 to 1, including a 4.3 axle rat