Patent GB-700367-A (GB)
Title: Improvements in or relating to change-speed gear mechanism for motor vehicles
IPC: F16H3/10
Filed: 1950-12-20
Abstract: 700,367. Change-speed gearing. NICKOLS, I H. Dec. 20, 1951 [Dec. 20, 1950], No. 31027/50. Class 80 (2) In four-speed constant-mesh countershaft gearing for motor-vehicles, with a normallyengaged direct-drive clutch 3 between the driving and driven shafts 1, 2, the countershaft '8, constantly driven from shaft 1 through gears 9, 10, drives the gear 7b for first-speed constantly through splines and the gears 6b, 5b for second and third speeds through normallyengaged, clutches 6c, 5c. the corresponding mesned gears 7, 6, 5, being connected to shaft 2 through one-way clutches 7a, 6a, 5a, while a reversely-acting one-way clutch 4 is provided between the shafts 1, 2. Thus, direct-drive through clutch 3 is normally operative, but by disengaging the clutches 3, 5c and 6c in succesion, third, second and first speeds are succesively established. The one-way clutch 4 ensures that shaft 1 is driven directly from shaft 2 on overrun in any speed. Additional normally-disengaged and simultaneously operable claw clutches 12a, 12b, are arranged between gears 6, 6a and shafts 2, 8, the clutch 12b having in series therewith a one-way clutch 12c, so that on over-run-in first speed, shaft 1 may be driven in second speed. Gear 7b is slidable on shaft 8 for engaging a reverse idler 11. The claw clutches 3, 5c, 6c may be associated with baulking rings which prevent engagement except on sychronism of the parts. The engine is connected to shaft 1 through a fluid coupling or centrifugal clutch. The gearing may be operated automatically under combined accelerator and engine-speed control. Electrical mechanism for this purpose comprises a finger displaceable according to engine speed and operating four switches carried by a member displaceable by the accelerator, these switches comprising a change-up switch at one end and spaced change-down switches for third, second and first speeds. Each change-down switch controls a solenoid which, when energized, disengages the clutch associated with the next higher speed, a holding switch being associated with the solenoid to maintain such energization. With the vehicle at rest and the engine idling, the three solenoids are energized. On accelerating. the vehicle moves off in first gear and the finger moves towards and eventually closes the change-up switch, whereby the throttle is closed through energization of an over-riding throttleclosing solenoid and a selector switch associated with the second-speed solenoid is opened to deenergize that solenoid so that second speed is established. On accelerating in second speed, the change-up switch is again eventually closed whereby the throttle is closed and a selector switch associated with the third-speed solenoid is opened to bring in third-speed. Top speed is then similarly brought in by accelerating in third speed. If the speed falls or the accelerator is released the finger successively closes the change-down switches and the lower speeds are successively established. The selector switches are displaced both on energization and on deenergization of the solenoids so as to be in proper position for operation, and contacts associated with the clutch solenoids momentarily actuate a relay as a clutch is engaged, to break the circuit of the throttle-closing solenoid. Means are provided to prevent establishment of top or third speeds when the clutches 12a, 12b are engaged, and for momentarily closing the throttle during the initial disengagement of the clutches.