MECHANICAL GEAR-CHANGING DEVICE

摘要

A mechanical gear changing device in a gear change box for motor vehicles, for engaging and disengaging positive drive clutches, with selector rails of rectangular cross-section running parallel with the gear-box shaft and each associated with a channel in the basic gearbox, the selector rails being arranged as a set and for example at an angle of 45.degree. to the centre of the gear-box shaft, and being mounted in the gearbox housing. The selector rails are provided with recess in which drivers, with rounded contact surfaces, are engaged by gear change levers mounted in the gear-box housing and/or gear change fingers arranged, for example, upon a selector shaft, or are secured to selector forks with selector rails. All of the selector rails (2,3,4), of similar cross-section, are mounted directly and jointly in the gear-box housing at least at two locations and are adapted to pivot through 90.degree. in order to co-operate with the selector fingers(91,92,93) arranged approximately vertically or horizontally. The common centre of rotation of the selector rail is arranged in such a manner that the same gear change levers or selector forks are actuated by the associated selector rails and that the respective gear change levers and/or selector forks associated with the channels remain unchanged as regards position and shape. The selector rails are preferably guided in circular bearing bushes (8,80) securable to the housing, each also carrying a locking plate which is specially shaped and is provided with an opening and, in the case of a group transmission, a blocking plate (65), cooperating with the selector rails and passing partly through the recesses. The locking plate is actuated positively by a selector rail provided with notches (23,33,43) in an end recess (24,34,44) when it is shifted to an operative position. The other two selector rails are locked by radial displacement or pivoting. The locking device requires only this one locking plate, whereas the other parts are already present in the circuit and may be easily adapted. Under the action of a spring (99), blocking plate (65) presses a nose(68)at all times against a control cam(96)on selector rail 95 for the group transmission and blocks the selector rails (2,3,4) of the basic gear-box during a gear change in the group transmission when the said nose engages in indentation(97)in control cam (96).