Patent GB-608535-A (GB)
Title: Improvements in or relating to control mechanism for vehicle change speed transmission
IPC: F16H37/00
Filed: 1946-02-26
Abstract: 608,535. Controlling change-speed gearing. BORG-WARNER CORPORATION. Feb. 26, 1946, No. 5954. Convention date, July 1, 1944. [Class 80 (ii)] Upshift and downshift of a planetary or countershaft overdrive behind a main vehicle variable-speed gear are effected by electromagnetically or electrohydraulically operated positively interengaging elements, above a predetermined vehicle speed and when the main gear is in a forward ratio, by release or kickdown respectively of the accelerator pedal, the latter movement also momentarily disabling the vehicle ignition to unload the transmission and permit the shift. As shown, a solenoid 27, Fig. 1, controls the radial movement of a pawl 26 engaging a slotted disc 25 rigid with the reaction sun 14 of a planetary overdrive, the carrier 13 and annulus 15 of which are connected to driving and driven shafts 10, 19 respectively which are also connected for direct drive by a roller free-wheel clutch 21. The pawl 26 is so constructed that it cannot be engaged or disengaged unless the disc 25 is stopped as by slowing of the driving shaft 10 relative to the driven shaft 19. The solenoid 27, when operative, tends to move the pawl 26 towards engagement against spring action, and so to open three earthed switches 29-31 normally held closed by the pawl stem and which are incorporated in the control circuit, shown diagrammatically in Fig. 2. The switch 30 is arranged when closed to complete, through a relay 35 and a manual vehicle ignition switch 37, the circuit of an earthed battery 38. The switch 29, together with the operating coil 32 of the solenoid 27, are in parallel with the switch 31, which controls a lamp 34 indicating when the solenoid is operative; and both switches are also connected, through two further switches 41, 39, to the battery 38. A solenoid holding coil 33 is provided in parallel with the operating coil 32. The switch 39 is operated by the control mechanism (not shown) of the main vehicle variable-speed gear, and is so arranged as to be opened when the latter is in neutral or reverse and closed when a forward gear, say direct drive, is engaged therein. In series with the switch 39 is both a relay 40, which when energized opens the normally closed switch 41, and a speed governor controlled switch 42 set to open above a predetermined vehicle speed. The speed governor (not shown) is powered from the driven shaft 19 by gearing 22, 23 which may also drive a speedometer or other auxiliary mechanism. The switch 42 is shunted by a switch 47 opened only when a relay 46 is energized from the battery 38 by the bridging of contacts 44 forming one of a pair of such contacts controlled by a member 43 under the action of the accelerator or throttle 43a. The other contacts 45 are in a circuit which, when completed, disables the vehicle ignition, being in series with a switch 36 controlled by the relay 35 and opened only when the latter is energized. With the vehicle stationary, the ignition switch 37 disconnected and the main gear in neutral, the control circuit is in the condition shown in Fig. 2, the solenoid 27 being de-energized and the pawl 26 disengaged. Upon closing the ignition switch 37 and engaging the appropriate main forward speed to close the switch 39, the relays 35, 40, 46 are energized and the switches 36, 41, 47 opened. When the predetermined vehicle speed is exceeded, the switch 42 opens and de-energizes the relay 40, closing the switch 41 and completing the circuit to the coil 32; so that upon release of the accelerator pedal to slow the driving shaft 10 relative to the driven shaft 19 until the disc 25 stops, the pawl 26 engages under the solenoidal pull to bring in the overdrive. The circuit is then in the condition shown in Fig. 5, with the switches 29-31 open and only the holding coil 33 of the solenoid operative, the de-energization of the relay 35 allowing the switch 36 to close. To shift down to direct drive, the accelerator pedal is fully depressed, when the member 43 leaves the contacts 44 and bridges the contacts 45. The consequent de-energization of the relay 46 closes the switch 47 and energizes the relay 40 to open the switch 41 and disable the coil 33, whilst the bridging of the contacts 45 interrupts the engine ignition, so that the shaft 10 again slows and the pawl 26 disengages, cutting out the overdrive. The subsequent closing of the switches 29-31 opens the switch 36 through the relay 35 to cut in the ignition despite continued depression of the accelerator, upon release of which the switch 41 will close and the overdrive be again engaged. A positive clutch 17 between the driving shaft 10 and driven shaft 19 is also provided. The pawl 26 may be replaced by an axially moving pawl, or, in the case of a countershaft overdrive, by an axially movable clutch member, and may be operated by the solenoid 27 through a fluid or other relay.