GB593973A - Synchronising couplings - Google Patents

Abstract

593,973. Toothed and variable - speed gearing; clutches. LEA-FRANCIS CARS, Ltd., (formerly LEA-FRANCIS ENGINEERING (1937), Ltd.), and RIDLEY, J. C. June 21, 1945, No. 15828. [Classes 80(i) and 80(ii)] A coupling device, particularly for use as an isolating clutch at the tail end of a vehicle gear box, utilises a differential gear in which the planet gears are clutched together to give a solid drive and disconnected to free the drive. As shown a bevel gear 11, mounted upon the driving shaft 29 through the intermediary of a splined sliding sleeve 28, engages planet gears 13, 14 carried by a cage 15 secured through a flange 21 to the driven shaft 25, the other bevel gear 12 being freely mounted but having a one-way driving connection 33, 35 with the driven shaft 25. For normal solid drive the planets 13, 14 are clutched together by the engagement of a sliding dog clutch element 37 on the gear 13 with a fixed clutch element 36 on the gear 14. The clutch 37, 36 is disconnected to free the drive when required by a sliding member 45 which moves with sliding sleeve 28, operated through a fork 49 and a rod 50 by the main clutch or change-speed lever of the vehicle so that an operation of changing gear disconnects the coupling. The member 45 engages between coned flanges 44 on the sliding dog clutch element 37 moving it against a spring 38 to free the planet gears which can then rotate to allow the driving shaft 29 to slow up while the movement of driven shaft 25 continues. This rotation of the planet gears introduces centrifugal force by balls 42 which acts to hold the dog clutch 37, 36 disengaged. Thus this clutch cannot be re-engaged until the planet gears stop rotating, which is the condition when the shaft 29 has reached synchronism with shaft 25 after the gear change has been completed. The spring 38 then moves the clutch element 37 to retract the balls 42 and engage element 36 to reestablish a solid drive, the sliding member 45 having been withdrawn by previous main clutch or gear lever operation. The oneway device 33, 35 is provided to prevent the driving shaft over-running the driven shaft should the dog clutch 37, 36 fail to re-engage, due for instance to overacceleration of the engine. The device allows. a reverse drive from the driving shaft 29 to the driven shaft 25 to be obtained without the introduction of any auxiliary. mechanism for this purpose. The bevel gear 12 may be secured to the driven shaft 25 instead of the planet cage which latter is then freely mounted with or without a one-way driving connection onto the driven shaft.