Patent GB-890371-A (GB)
Title: Improvements in and relating to electrical means for automatically controlling change speed gearing
Inventor: RAWLINS BERNARD GEORGE
IPC: F16H63/02
Filed: 1959-04-16
Abstract: 890,371. Change-speed control. SELF - CHANGING GEARS Ltd. April 16, 1959, No. 12984/59. Addition to 802,272. Class 80 (2). In an automatic change-speed control of the parent Specification wherein primary gearchange relays 3P, 4P, 5P are energized in one direction only by a generator G driven from a member of the gearing to provide a speedresponsive voltage in opposition to differing relatively fixed voltages tapped from a batteryfed potentiometer, and extra resistors R1, R2 in series with the potentiometer are progressively short circuited via contacts T1<SP>1</SP>, T2<SP>1</SP> to increase the opposing voltage by relays T1, T2 energized by a throttle pedal switch arm 3 in " Normal " and "Full" positions, a capacitor QB is provided to prevent undesired upward gear changes resulting from reduction in the opposing fixed voltage due to rapid throttle movement to the idling position by delaying the insertion of the extra resistors R1, R2 until an additional relay N is first de-energized to close contacts N1 to short circuit the resistors R1, R2. The switch arm 3 wipes contact quadrants 4, 5, 6, K corresponding to " Light," " Normal," " Full " and " Kickdown " throttle pedal positions. In " Idle " throttle position of the arm 3 the contacts N1 are closed. Movement of the arm 3 to " Light " energizes relay N through changeover contacts T1<SP>11</SP>, T2<SP>11</SP> thereby opening contacts N1 to insert resistors R1, R2 for minimum opposing voltage and closing contacts N2 to charge the capacitor QB connected in parallel with the relay N. Further movement of the arm 3 to " Normal " energizes the relay T1, thereby closing contacts T1<SP>1</SP> to short circuit R1 and actuating the change-over contacts T1<SP>11</SP> to maintain energization and charge respectively of the then parallel relay N and capacitor QB. Still further movement of the arm 3 to " Full " energizes the relay T2 thereby closing contacts T2<SP>1</SP> to short circuit R1 and R2 and actuating the change-over contacts T2<SP>11</SP> to maintain energization and charge respectively of the then parallel relay N and capacitor QB. The charged capacitor QB affords delay in the release of all relays in parallel therewith; however, the relay N is arranged to release first and the contacts N1 are arranged to close before any other contacts operate at the end of the capacitor delay period. Should the driver release the throttle for emergency braking the relay N releases first and the contacts N1 close to shortcircuit the resistors R1, R2 to supply full opposing voltage and prevent undesired upward gear change. The primary relays 3P, 4P, 5P control contacts 3P1, 4P1, 5P1 of secondary relays 3S, 4S, 5S which in turn control electromagnetic valves " First," " Second," " Third " and " Fourth " determining corresponding gear ratios. Optional contacts N4 controlled by the relay N engage first gear when the throttle is opened. To prevent downward changes when the arm 3 moves from " Normal " to " Light," such changes resulting from release of the relay N prior to the operation of the changeover contacts T1<SP>11</SP> to establish an alternative supply line, the secondary relays are provided with holding coils energized through secondary relay contacts 3S1, 4S1, 5S1 and also through contacts N3 arranged to close simultaneously with the contacts N1. If the arm 3 is eased back from " Full " to " Normal " the existing short-circuit of the resistors R1 and R2 is maintained upon release of the relay N, after which the relay T2 releases, whereupon only the resistor R1 is short-circuited by the relay T1, the relay N being re-energized through the contacts T1<SP>11</SP> and T2<SP>11</SP>. During slow progressive movement of the arm 3 from " Full " to " Light " the resistance in series with the potentiometer is progressively increased. However, an upward gear change may be deliberately precipitated by rapid movement of the arm 3 from " Full " to " Light " to suddenly included resistors R1 and R2 in the circuit. In " Kickdown " throttle pedal position a relay KD is energized to open normally-closed contacts KD1, KD2, KD3 to insert resistors R3, R4, R5 respectively in circuit with the primary relays 3P, 4P, 5P to oppose generator voltage and effect downward changes at higher vehicle speeds. During " Kickdown " the resistors R1, R2 are short-circuited. A manual gear selector switch M affording automatic operation in its position A is provided.