| 摘要 |
A synchronizing and dog coupling device for a motor vehicle gearbox in which there are two pinions arranged to be coupled selectively to a drive shaft of the gearbox comprises a coupling ring which is engaged through a driving collar for rotation with the drive shaft and which has a plurality of radial bars, a double synchronizer ring having conical friction surfaces for co-operation selectively with friction surfaces on said pinions, and locking surfaces on said synchronizer ring and said coupling ring bars co-operable to prevent engagement of said coupling ring bars with dog teeth on one or other of said pinions until the speeds of said coupling ring and said pinion are synchronized, the synchronizer ring being braced by a set of rocking keys each of which is located in an axial groove in the driving collar and is arranged to rock on a radially outwardly biassed thruster, each key having first and second sloping sided transverse notches for co-operation respectively with the coupling ring and the thruster so that when the coupling ring is moved to uncouple it from one of the pinions the rocking keys move to re-center the second notches on the thrusters and thereby disengage the friction surfaces of the synchronizer ring and the pinion.
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