Patent GB-817260-A (GB)
Title: Improvements in and relating to electrical control means for change speed gearing
Inventor: MILLER ALBERT ARTHUR
IPC: F16H63/30
Filed: 1955-09-13
Abstract: 817,260. Change-speed control. SELFCHANGING GEARS Ltd. Dec. 6, 1956 [Sept. 13, 1955], No. 26203/55. Class 80 (2). [Also in Group XXXVII] Electrical control means for change-speed gearing comprises a ratchet actuated step-bystep operated multiple contact selection switch for controlling gear engagement, electromagnetic drive means for the switch, relay means controlling the drive means and manuallyoperable switch means for controlling the relay means. The electrical control means is described as applied to the control of a fourspeed and reverse planetary gear in series with a two-speed auxiliary gear. the various speeds being established by fluid pressure-operated mechanism (not further described) under the control of valves each operated by an electromagnetic relay. The relays GL, GH, Fig. 1, control the establishment of the low and high ratios in the overdrive gear, the relay GR establishes reverse in the main change-speed gear, while the relays G1 ... G4 establish the four forward speeds in the main change-speed gear. A uni-selector switch comprising five contact arms 14, 15, 23 ... 25 moved together over contacts R2, R1, N, 1 ... 8 controls the energization of selected relays GL &c. The uniselector switch is of the type wherein the contact arms 13a, Fig. 2, are mounted on a common shaft 9a to which is secured a gear-wheel 10a. Pawls 11a are mounted at the ends of armatures 15a pivoted against spring bias by the energization of solenoids DM, UM to engage the pawls with the gear-wheel 10a and thus move the contact arms 13a round in one direction or the other a step at a time. Energization of the solenoid DM, UM is effected in response to movement of a single control handle-operating switches, described below, to a " down " or an " up " position. To effect an up shift, a switch 26, Fig. 1, is closed to energize a relay UR which closes a switch URC and thus energizes the magnet UM in the uni-selector switch. Accordingly all the contact arms 14, &c. move one step and the appropriate ratio selecting relay G1, &c. is energized, the previously energized relay being simultaneously de-energized. To effect a down shift, the control handle is moved to its other position, thus closing two switches 33, 34 to energize a relay D1. This closes a switch 30 so that a relay D2 is energized to close a switch 31 and supply current to the solenoid DM of the uni-selector switch. Accordingly the contact arms 14, &c. are all moved one step in the downward direction. A switch 40 is controlled by a speed governor device driven from the engine of a vehicle in which the gearing is mounted, and has three operative positions; a first, GS, when the engine idles, a second, as shown, at an intermediate speed range, when it is open, and a third, GF, above a predetermined engine speed. If the ratio selected in the gearing is one of the top three ratios 6 ... 8 and the engine is allowed to idle, the switch 40 moves to its GS position and a circuit is completed through the contacts arm 25 and the down-shift relay D1. Succeeding down-shifts then occur automatically until the fifth speed is reached, when the circuit through the contact arm 25 is broken. Further down-shifts to neutral are obtained by manual operation of a press button (not shown) to close a down switch 42 and a condenser lag reducing switch 43. If the vehicle engine exceeds the predetermined speed, the switch 40 is moved to its GF position which energizes a relay INH to open a switch 32. Manual down-shift by closing the switches 33, 34, as already described, is then ineffective to produce a down-shift in the gearing, so that the engine cannot be subjected to excessive speeds of revolution. To override the speed safety control of the engine, switches 37, 38 are closed as well as the switches 33, 34 for a down-shift, thus energizing the down-shift relay D1, D2 directly. To engage reverse, the control handle is moved to a position where it closes the downshift switches 33, 34 and also the switches 37, 38. The latter closes the down-shift relay D2 so that the down-shift solenoid DM of the uniselector switch moves the contact arms 14, &c. to the first or second reverse position. To interrupt torque transmission in the auxiliary gear until a newly selected ratio has been established in the main gear, a switch 58 (not shown in Fig. 1), controlling the supply of current to the contact arm 14, is opened by operation of the control handle. The circuit is under the control of a main switch 11 which in its " on " position does not energize the selector arm 24. In its " off " position, the selector arm 24 is energized and, if the ratio established in the gearing is other than neutral, energizes either the down relay D1, &c., to effect downshifts until neutral is reached, a switch 41 actuated by the uni-selector switch solenoid DM operating as a make-and-break, or, if the gearing is in reverse, energizes the up relay UR to effect up shifts until neutral is reached. Warning lights 46 show when the main switch 11 is in its " on position. The control handle 49, Figs. 4... 8, selecting the ratios in the gearing, is fast with a shaft 48 to which are secured three cams 55 ... 57. The cams operate the switches 26, 58, 33, 34, 37, 38. The handle 49 and the shaft 48 have four operative positions; a central position 50, Fig. 8, when none of the switches are actuated, a position 51 reached by anti-clockwise movement from the central position 50 for down-shifts, an up-shift position reached by clockwise movement from the central position, and an overriding position reached by further clockwise movement from the up-shift position against spring bias. The lever 49 is moved to its override position for down-shifts at high speeds when the governor switch otherwise prevents such shifts, and to engage reverse from neutral. The handle 49 and shaft 48 are restored to the central position 50 by mechanism comprising a cam 54, Fig. 7, fast on the shaft and having recesses engaged by rollers 69 on levers 67 biased towards each other by springs 70. The shaft 49 is turned to its override position against bias of a spring 65, Fig. 6, secured to a plate 62 carrying a pin 66 lying between two lobes 60 on a plate 59 fast with the shaft 48. In turning the shaft 48 from the central position 50 to the up-shift position, the lost-motion between one of the lobes 60 and the pin 66 is taken up, and on further turning of the shaft 48 in the same direction, the plate 59 turns the plate 66 and thus stretches the spring 65. Specification 793,318 is referred to.