Patent GB-867879-A (GB)
Title: Improvements in or relating to automatic gear change controls
Inventor: WORSTER NORMAN GEORGE
IPC: F16H61/02
Filed: 1958-01-16
Abstract: 867,879. Change-speed control. SMITH & SONS (ENGLAND) Ltd., S. Jan. 15, 1959 [Jan. 16, 1958], No. 1593/58. Class 80 (2). Change-speed control mechanism, particularly for Diesel trains of the kind having a number of power units in different coaches, the gearing being planetary and giving four ratios, selects the ratios in dependence on the electric signal produced by an output-driven generator SG supplying current through resistors R1, R2, R3 consecutively brought into operation by a rotary switch 12a turned to positions C; E, G according to whether the second, third or fourth ratios have been established, so that the signal supplied from the generator through parallel rectifiers MR1, MR2 to upshift and downshift relays CR1, CR2 is modified following a ratio shift. The modification is such that - the generator SG must rotate at a higher speed after an upshift than before the shift, and must rotate at a lower speed after a downshift than before the shift, to produce the same two respective signals. The speeds at which ratio shifts are established is also modified by a driveroperated power control switch 24 having positions 1 . . . 4 which selectively connect a positive line 10 to lines T1 ... T4 actuating electrical control mechanism 25 adjusting the setting of the Diesel engine throttle, and also actuating relays RL1 ... RL3 having contacts which introduce resistors R5 ...R7 into the generator circuit. The arrangement is such that moving the power control 24 in the direction towards position 4 to give increased power from the Diesel engine introduces additional resistance in the circuit from the generator SG, and vice versa. To start the train from rest, the power control 24 is set to the idle position, and the driver's key closes a switch 23 energizing a relay RL6. A thermally controlled switch 21 is then set to its automatic position, connecting a negative power line 11 to the relay RL6, which is accordingly energized. The relay RL6 closes its contacts and connects a subsidiary d.c. voltage source 22 in circuit, and also closes contacts GA, GB leading from the generator SG to an adjustment box WB and the speed-sensitive control circuit. The rotary switch 12a is ganged together with similar rotary switches 13a ... 19a for simultaneous movement. In the position of rest shown, the rotary switch 17a connects the positive line of the source 22 through a relay RL10, which opens its contacts. The power control 24 is now moved to its position 1. The relay RL1 is thereby energized, via a closed contact RL4/2, connecting the positive line 10 through a closed contact RL11/1 of a change-over relay RL11 and a closed contact RL11/3 of the same relay to the rotary switch 16a which, in its present position, energizes a line G1 connected to mechanism 26 actuating valves through which hydraulic or pneumatic pressure is supplied to establish the first ratio in the gearing. The train accordingly moves off. The power control 24 is now moved to its position 2, so that it energizes both relays RL1, RL2. Contacts 2 of the relay RL2 modify calibration of the speedsensing circuit by introducing the resistor R5 into the circuit from the generator SG. In the third power control position 3, both the relays RL2 and RL3 are energized, whilst in the fourth power control position 4 only the relay RL3 is energized. In any particular engine power setting, the calibration of the speed sensing circuit is modified to the appropriate gear change. When the track speed of the train has increased sufficiently, the upshift relay CR1 operates to close contacts CU and thereby energize a relay RL7 from the subsidiary source 22. The relay RL7 energized a coil RSU which operates a step-by-step mechanism (not further described) to turn all the rotary switches 12a . . . 19a through 45 degrees, from a position A (shown on the rotary switch 12a) to a position B. In this position, the rotary switch 12a modifies the calibration of the speed sensing circuit of the generator SG by introducing therein the resistor R1. Simultaneously, the rotary switch 14a energizes the relay RL4 which de-energizes the throttle lines T1 ... T4. Accordingly the train engine begins to slow down. Also, in the position B, the rotary switch 15a energizes a relay RL9. The contacts of this relay close to energize the setting relay RC of the downshift relay CR2. In position B, the rotary switch 16a supplies current to the gear establishing line G1 to maintain first gear established. The rotary switch 18a in position B energizes a relay RL5 to connect a fourth ratio line G4 to relay contacts controlled by the relay RL3. In this position, the rotary switch 17a de-energizes a relay RL10 which, after a short time delay, determined by the value of capacitors C5, C6, disengages and applies a second pulse of current through its contacts from the rotary switch 15a and through the rotary switch 19a to the upshift coil RSU. Accordingly all the rotary switches 12a ... 19a are stepped around another 45 degrees to the position C. The rotary switch 14a now de-energizes the relay RL4, which re-energizes the appropriate throttle line so that the engine speed once more increases. Simultaneously, the rotary switch 15a disconnects the relay RL9 and also disconnects the supply of current to the upshift coil RSU through the contacts of the relay RL10. The rotary switch 16a de-energizes the first ratio energization line G1, and energizes the second ratio energization line G2. The rotary switch 17a in the position C energizes the relay RL10 to open its contacts. The second ratio has now been established. A shift up from second to third ratio is identical to this shift, with the exception that the rotary switch 13a modifies the operating track speed of the relay CR1 by short-circuiting a resistor UR2, in addition to the modification of the operating track speed by the rotary switch 12 bringing the resistor R2 into the circuit from the generator SG. Again, the upshift from the third to the fourth ratio is also identical. When the speed of the train falls to an appropriate value, the downshift relay CR2 operates, closing contacts CD to energize a relay RL8. This closes its contacts RL8/1 to energize the change-over relay RL11, and contacts RL8/2 to energize a downshift coil RSD which thereby steps all the switches 12a ... 19a through one step or 45 degrees, in the opposite direction, to a position F, D or B depending on the ratio already established. Energization of the change-over relay R 11 opens its. contacts RL11/1 so that the power control relay RL4 is de-energized, and also deenergizes the appropriate gear energization line G1 ... G4. The engine revolutions therefore rise. Contacts RL11/2 of the relay RL11 disconnect the time delay capacitor C5 to reduce the time delay of the fall off of the relay RL10. The contacts RL11/3 of the relay RL11 maintain the energization of the relay RL11 through the rotary switch 15a during the whole period of a downshift. The rotary switch 15a in the position F, D or B energizes the relay RL9 to reset the downshift relay CR2 by energizing its resetting coils RC. Simultaneously, the rotary switch 17a de-energizes the relay RL10, which, after a short time delay, due to the capacitor C6, closes its contacts and, through the now closed contacts RL11/4 of the relay RL11, contacts RL11/5 having been opened by the relay RL11, energizes the downshift coil RSD again to step the rotary switches a further 45 degrees in an anti-clockwise direction to one or other of positions E, C or A. The rotary switch 12a modifies the calibration of the speed sensing circuit by cutting out one of the resistors between the generator SG and the upshift and downshift relays CR1, CR2, and the rotary switch 15a breaks the supply to the relays RL9 and RL11. The rotary switch 17a re-energizes the relay RL10, and the circuit is now restored to the same condition that it was in after an upshift. If any ratio other than first is established in the gearing, and the power control 24 is moved to the idle position shown, the relays RL1, RL2 and RL3 are conditioned to energize the fourth ratio line G4. With changes in track speed, the upshift and downshift relays CR1, CR2 function to select the appropriate ratio on the rotary switch 16a, although current is supplied only to the fourth ratio line G4. If the track speed falls to a value which would normally energize the first ratio line G1, the rotary switch 18a deenergizes the relay RL5 and the fourth ratio line G4 is de-energized by the contacts of this relay. The gearing is accordingly restored directly to neutral. If, however, the power control 24 is retained to one of its positions 1 ... 4 before this latter position is reached, then the appropriate ratio will be selected relative to track speed and throttle setting. A thermal overload is provided on the switch 21, so that in the event of failure of the relay CR2, with consequential permanent energization of the rotary selector coils RSU, RSD, the circuit is broken.