Patent GB-522969-A (GB)
Title: Improvements in and relating to change-speed gear control devices
IPC: F16H63/46
Filed: 1938-12-21
Abstract: 522,969. Controlling change-speed gearing. PESCARA, R. P. Dec. 21, 1938, Nos. 37206 and 37207. Convention dates, Dec. 22, 1937, and March 5, 1938. [Class 80 (ii)] Change-speed gearing on a vehicle is conrolled in part by a vehicle-driven centrifugal governor which places at the disposal of the operator different combinations of ratios in predetermined speed ranges, individual ratios in such combinations being selected by and at the will of the operator. As shown in a simple form, Figs. 1-4, providing three speeds and reverse, the arrangement is such that below a predetermined vehicle speed (e.g. 6 km. per hour), repeated depressions of the main clutchpedal produce alternately first and reverse speeds, whilst above this speed, the same action produces alternately second and high speeds. Striker-forks F', F controlling respectively high- and second-speeds, and low- and reverse-speeds, are fast to rack-toothed slides A0, A2, geared through pinions 1, 1<1> to oppositely-moving racktoothed slides A<1>, A<3> respectively, whereby movement of the striker-forks in either direction from neutral is effected by movement of the appropriate slide A0, A1, A2, A, to the right of Figs. 1-4 from the neutral position. Neutralizing and subsequent engagement of a selected speed are both effected in a single downward stroke of a main-dutch pedal P, which rocks a shaft 3 carrying groups of cams, one group C0, C1, C2, C3, always fast to the rockshaft 3, serving to neutralize the gear during the first part of the pedal-stroke by acting on short projections B0, B1, B2, B3, hinged to each of the slides A0 &c. so as to centralize the latter, whereafter a second and selectively controlled cam-group C<1>0, C<1>1, C<1>2, C<1>3, acts on longer hinged projections B<1>0, B\, B<1>2, B<1>3 to impart a supplementary rightward travel to a selected slide A0 &c. and engage the new speed. Springs 52 allow the hinged projections B0 &c. and B<1>0 &c. to yield upwardly during the consequent leftward travel of the connected slide, the short projections B0 &c. being lifted idly by the return movement of the neutralizing cams C0 &c. whilst the longer projections B', are cammed upwardly above the rockshaft by fixed stops 101. The selective control of the executive cam-group C<1>0 &c. is effected in part by a vehicle-driven centrifugal governor 18, Fig. 3, arranged in a brake-drum 17 which, above a speed of 6 km.p.h. opens contacts 21, de-energizing a solenoid 10, the bevel-ended armature 8 of which is thereby lifted by a spring 12 away from the upper end of a centrally-pivoted keymember 5 inside the rockshaft 3. A bladespring 9 thereupon tilts the key-member 5 so that an upper key 6 thereon is withdrawn from. engagement with the cam-pair C<1>0, C<1>1, controlling low-speed and reverse, whilst a lower key 6<1> thereon moves outwardly into engagement with the cam-pair C<1>2, C<1>3, controlling second- and high-speeds. Thus, below a speed of 6 km.p.h. (position shown), the cam-pair C<1>0, C<1>1, is keyed to the executive rockshaft 3 and the cam-pair C<1>2, C<1>3 is loose thereon, giving the operator control of only low-speed and reverse, whilst above this speed the cam-pair C<1>2, C<1>3, is keyed and the cam-pair C<1>0, C<1>1, is loose, giving control of second- and high-speeds only. Sequential preselection of alternate ratios in either speed-range is controlled by axial movement of the operative cam-pair, effected by springs r, r<1> and a stronger common spring 14, the latter acting on the cam-pairs C<1>0, C<1>1 and C<1>2, C<1>3 through forked levers 4, 4<1>, and its tension being controlled through levers 13, 13<1> by ramps 16, 16<1> on the low- and highspeed slides A1, A, respectively. When all four slides are in the neutral position shown, the ramp 16' on the high-speed slide A3 is effective to tilt the lever 13' away from the lever 4<1>, whilst the ramp 16 on the low-speed slide A, frees the lever 13 and permits its free end to be drawn downwards by the spring 14. The cam-pair C<1>0, C<1>1 is thereby lifted, against its spring r, into the position shown in which the cam C<1>1 comes opposite the projection B<1>1 ready for operating the low-speed slide A, when the clutch pedal is depressed. At the same time the freeing of the lower lever 4<1> permits the spring r<1> to raise the cam-pair C<1>2, C<1>3 into the position shown in which the cam C2<SP>1> is opposite the projection B<1>2 ready for operating the second-speed slide A2. In the low-speed range this latter cam-pair is not keyed to the rockshaft 3 and is therefore inoperative. Throughout the depression of the clutch-pedal the cam-pairs are both locked against axial movement by fixed projections 104, Fig. 1, embracing flanges 103 thereon. Depression of the clutch-pedal from the position shown in the low-speed range, therefore results in the cam C\ engaging low-speed, completion of which causes the ramp 16 to raise the free end of the lever 13, and free the lever 4. When the clutch-pedal has been fully released, the cam-pair is released from the fixed projections 104, whereupon the compressed spring r moves the cam-pair to a lower position in which the cam C<1>0 comes opposite the projection B<1>0 on the reverse slide A0. In the low-speed range, the next depression of the clutch pedal would therefore engage reverse, resulting in a leftward movement of the low-speed slide A, which, on release of the clutch-pedal, would restore the cam-pair to the position shown, ready for selection of low-speed on the next depression of the clutch-pedal. If, however, the vehicle speed has exceeded 6 km.p.h. in lowspeed or reverse, the cam-pair C<1>0, C<1>1 is free of the rockshaft and the cam-pair C<1>2, C<1>2 keyed thereto, so that the subsequent depression of the clutch-pedal selects second speed through the cam C\. Alternate preselection of second- and high-speeds then takes place under control of the ramp 16<1> in the same manner as for lowspeed and reverse in the low-speed range above described. The clutch-pedal P acts on the rockshaft 3 through an adjustable stop 24<1> and a loosely mounted toothed sector 24 engaging a pinion 23, connected to the rockshaft through a yielding torsion-spring 22, which is pre-stressed by pins 25 engaging slots in the ends of an internal sleeve. In order to reduce the pedaleffort due to the clutch springs, the clutch is actuated through a lost-motion connection 27, Fig. 4, by an arm 28 fixed to the pedal shaft 29 so that the clutch is actuated towards the end of the pedal stroke when the connecting link 26 is nearest the pedal shaft 29 and so operating at a greater leverage. The Specification as open to inspection under Sect. 91, comprises also the following. In the arrangement shown in Fig. 5 (Cancelled), three striker-forks F, F<1>, F", controlling four forward speeds and reverse are operated by oppositelygeared slides A0, A<1>0, A1, A2, A3, A4, the firstnamed slide A0 being provided merely for neutralizing reverse, the second, A<1>0, engaging reverse, whilst the remaining slides each correspond to ascending speeds in the order named, all gear-engaging movements being to the right of Fig. 5 (Cancelled), from a central neutral position of the slides. The selection of speeds is arranged to take place in the following sequence. Below a vehicle-speed of 6 km.p.h. successive depressions of the clutch-pedal produce low-speed and reverse alternately, between 6 and 60 km.p.h. second and third speeds alternately, and over 60 km.p.h. third and fourth speeds alternately. A change direct from fourthto second-speeds is also possible. This arrangement is for use with a transmission having a direct-drive third-speed and an overdrive high, which latter can thus only be introduced above 60 km.p.h. A modification, described below, is for use with a direct-drive high-speed which can be introduced at any speed above 6 km.p.h. The slides A1 &c. each carry short and long projections B1, B<1>1 &c. co-operating respectively with neutralizing cams C0, C, ... C4 fast to a clutch-actuated rockshaft 3, and axially-movable executive cams C<1>0, C<1>1 ... C<1>4, selectively connected thereto. The reverse, first- and second-speed cams C<1>0, C<1>1, C<2>2 are formed integrally together and are adapted to be keyed to the rockshaft 3 in alternation with an integrally formed third- and fourth-speed cam-pair C<1>3, C<1>4 by means of a centrally pivoted internal key-member 5, having key-projections 6, 6<1> at its ends as in Fig. 3. A blade-spring 9 maintains the cam-trio C<1>0 &c. keyed, as shown, until de-energization of a solenoid 10 allows a spring 12 to force down a bevel-ended plunger 8, freeing the cam-trio and keying the cam-pair C<1>3, C<1>4. The axial position of the cam-trio C<1>0 &c. is controlled by centralizing springs r', r<11> and a pair of oppositely acting solenoids 110, 111. With all the slides A0 &c. in the neutral position, and below a vehicle speed of 6 km.p.h., the cam-trio C<1>0 &c. is raised to bring the cam C<1>1 opposite the first-speed projection B<1>1, by energization of the solenoid 110 through contacts 112' and a change-over switch 113. Rocking of the shaft 3 by the clutch-pedal thus produces first-speed, the consequent rightward movement of the slide A1 changing over the switch 113 through a pushrod 115, de-energizing the solenoid 110 and energizing the solenoid 111, thus causing the cam-trio C, &c. to move to its lowest position when it is freed on the full release of the clutch pedal. In this position the cam C<1>0 comes opposite the reverse projection B\ so that a subsequent depression of the clutch-pedal engages reverse and the consequent leftward neutralizing movement of the low-speed slide A1 changes back the switch 113, re-energizing the solenoid 110 in place of 111, so that on release of the clutch-pedal the cam-trio C<1>0 is moved back up to the position shown ready for engagement of first-speed at the next depression of the clutch-peda