Patent GB-477301-A (GB)
Title: Improvements in and relating to power transmission mechanism and control means therefor
Filed: 1936-03-19
Abstract: 477,301. Controlling change-speed gearing. BENDIX AVIATION CORPORATION. March 19, 1936, No. 8246. Void. Convention date, March 20, 1935. [Class 80 (ii)] A power-operated change-speed control on a vehicle is provided with means, under the control of the accelerator-pedal, or the mainclutch, to ensure the continuation of powerapplication to the gear-change mechanism until the main-clutch is engaged sufficiently to ensure complete meshing of the selected gears. The control mechanism, which is preselective, comprises gear-establishing and cross-shift motors, acting on a ball-mounted shifter-lever, and energized by engine-suction under the selective control of electrical circuits, governed by a miniature hand-lever 230 moving in an H-gate, as described in Specification 457,068. The control mechanism further differs from that in the latter Specification by the addition of an electrical interlock switch, described below, enabling a preselective change, say direct from low to high gear, to be made. The means, referred to above, for ensuring powercontinuation, is shown in Fig. 31, wherein release of the accelerator-pedal 470 opens a valve 474, connecting a main-clutch withdrawal motor 492 to engine-suction at 476, and also energizing a suction-motor 480, which completes contacts 484, leading from a battery 486 to the selector switch of the change-speed control. The suction-conduit to the switchmotor 480 includes a ball valve 490, having a bleed-slot, which retards the re-opening of the contacts 484 after depression of the accelerator pedal, and consequent re-engagement of the clutch, whereby the change-speed control remains power-loaded until the clutch has re-engaged sufficiently to complete the meshing of the gears. To lock out the automatic operation of the main-clutch for manual operation thereof, there is a control button 456 adapted to withdraw a valve-plunger 430, .thereby venting the clutch-motor 492 and cutting off its connection with the suction-valve 474. Simultaneously, the button 456 operates a switch 468, cutting out the slow-opening switch 484, and supplying the change-speed selector switch through a circuit, shown dotted, including a similar switch, operated with lostmotion by the main-clutch pedal. In modifications, the switch-opening is further retarded by independently-acting dashpots, and the switch 484 is directly operated by a lost-motion lever connected to the accelerator-controlled valve 474. The clutch-switch and alternative circuit including it may be omitted. The changespeed control comprises a longitudinal, doubleacting gear-establishing motor 52 and a singleacting cross-shift motor 56, both acting on a ball-mounted three-speeds-and-reverse shifterlever 88, Figs. 2 and 4, through a rockshaft 64, which is turned by action of the gear-establishing motor on an arm 70, and slid bodily by the cross-shift motor, acting on the rockshaft through a bellcrank 78, Fig. 2. The crossshift motor 56 contains a spring 354, Fig. 25, which permanently biasses the shifter-lever into engagement with the selector-rod 60 for second and high speeds. For emergency use a simple manual lever, carried in the vehicle as an accessory, can be attached to the upper end 302 of the lever 88. The motors are supplied with engine-suction or atmospheric air under the selective control of three two-way valves 144, 146, 148, Fig. 25, of the piston or poppet type, arranged in a common triangular housing 54, and operated by solenoids 150, 152, 154, against spring-resistance which normally biases the valves into a position in which they vent their respective motors to atmosphere via an aircleaner 188. A check-valve is arranged in the suction inlet-port of the valve-housing. Fig. 25 shows a simple electrical circuit in which the power is switched on by a switch 204, closed by depression of the clutch-pedal 16. The engine-starter switch 342 is wired to the dead side of the switch 204 so that it is ineffective unless the clutch-pedal is depressed. The engine ignition-switch 344 forms a main cut-out, for the power. The gate-guided manual selectorlever 230 operates a pair of switches, 198, 200, which co-operate with two motor-operated switches to energize the required solenoids 150-154. One of these latter switches, known as a " wiper switch " 102, comprises two contact-bars 120, 122, operated by a longitudinal rod 100, Fig. 4, connected to the shifter lever 88, so as to be moved by its gear-establishing movement only. The bars 120, 122 wipe over and bridge contact-strips 110, 112 and 114, 116, thereby connecting the selector switch 200 with the solenoids, the arrangement being such that when a gear has been established, the appropriate bar 120 or 122 slides over the end of its strip 110 or 114, thereby de-energizing the operative solenoid, whilst the other bar remains in bridging contact ready for the next change. The latter bar also contacts with a central strip 118, leading to a neutralizing terminal 274 of the selector switch. The circuit is broken after a neutralizing operation by the operative bar 120 or 122 moving off the strip 118. This wiper switch, which is also described in Specification 457,068, is carried in a housing 102, Fig. 2. The other motor-operated switch 202, which was not used in the above-mentioned Specification, comprises in effect an electrical interlock which ensures that the gear is neutralized before the solenoid of the selected gear can be energised, thus making possible a preselected change from low to high. This switch is operated through a link 330, Fig. 2, by the cross-shift motor 56, and comprises a pair of contact-segments 322, 324, Fig. 25, which are rocked to bridge contacts 314, 316, 318, 320, in different pairs as required. The contact 320 leads to the contact-segment 278 of the three-way selector-switch 278 and forms the sole current supply to that switch. The contact 314 leads to the neutralizing strip 118 of the wiper switch 102, whilst the remaining pair 316, 318 lead to contacts 286, 290, forming part of the switch 200. The latter comprises a metallic sleeve 222, which is moved axially by the transverse selecting movement of the selector-lever 230, and additional contacts, one 288 of which constitutes the only current input to the entire selecting mechanism, whilst the other 284, leads to the solenoid 154 for energising the cross-shift motor 56. The sequence of operations involving a preselected change " through the gate " from one selector rod to the other is as follows. After the switch lever 230 has been moved through the gate to the desired position and the clutch-pedal depressed, the three-way selector switch 200 will remain dead, since its input contact 278 will be cut off from communication with the live contact 288 via its only route through the interlock switch 202, contact 286 or 290 and sleeve 222, since the latter moves off the previously operative contact 286 or 290 when the switch-lever 230 moves through the gate. The only initial current is through contact 286 or 290 and the interlock switch to the neutralizing strip 118 of the wiper switch 102, and, if the change is to low or reverse, current is also passed directly through the contact 284 to the solenoid 154 of the cross-shift motor. The gear is thereby neutralized through the wiper switch, which cuts off the operative current when neutral is reached. The shifter-lever 88 is then moved transversely through the gate by the crossshift motor 56 or its spring 354, whereupon the interlock switch 202 is operated to bridge different contact-pairs and energize the selectorswitch contact 278, the current being thereby directed to the selected solenoid 150 or 152, which is de-energised by the wiper switch 102 when the gear is established. A construction of selector switch, for mounting on the steering column, is shown and described in detail, but apart from the additional contacts 286, 290, and a main cut-out switch 292, is substantially the same as that described in Specification 457,068. A free-wheel tail-clutch is used. Specification 412,184 also is referred to.