An improved change gear system having a plurality of spaced countershafts having parallel axes and means supporting the countershafts in a casing for rotation. Countershaft gears are provided on the countershafts and are concentric and rotatable therewith. A rotatable main shaft is provided which is arranged substantially parallel with the countershafts and is preferably located between a pair of the countershafts. Means are provided for pivotally supporting one end of the main shaft in addition to means for guiding the other end thereof in a free floating relation relative to the one end for movement in at least a direction transverse of a plane through the axes of two of the countershafts. A plurality of axially constrained thrust rings are fixed to the main shaft for rotation therewith and cooperate with a fixed thrust plate for transferring thrust loads on the main shaft to the casing. Clutching means are provided for effecting a driving connection between the countershafts and the main shaft.
A twin countershaft transmission (100) is provided having axially adjacent floating mainshaft gears such as referenced by numerals (30) and (32) whose axial thrust when engaged is transmitted to the mainshaft (48) rather than to the adjacent gear by means of gears (30) and (32) having respective flanges (42) and (44) that extend radially inwardly between their axially spaced-apart thrust washers (46, 50, 52) splined to mainshaft (48).
A thrust washer combination employing three thrust washers (28, 70 and 72) is provided for maintaining separation between and for transferring axial thrust to a mainshaft (2) that has been imparted to either one adjacent floating mainshaft gears (12, 18) of a change gear transmission (100) respectively by a clutch assembly (20) or (22) during the process of selectively clutchingly engaging one of gears (12, 18) to the mainshaft to effect the rotation thereof. Gears (12) and (18) have respective adjacent flanges (42) and (44) that extend towards mainshaft (48) with thrust washer (28) being contained in an annular groove (42) therebetween and keyed for rotation with mainshaft (2) and thrust washers (70) and (72) positioned on opposite sides of flanges (40, 42) and held thereagainst by retaining rings (74) and (76) respectively.
Multi-speed step-change transmission for commercial vehicles having an one input shaft, a main shaft placed in an axial extension, one countershaft parallel thereto and one intermediate shaft parallel to the two shafts for the reverse gear and the shafts have gear wheels forming the ratio steps of the transmission. The sum of the tip radii of the intermediate gear (3) for the reverse gear and of the main shaft gear (1) for the first gear is smaller than the axial separation (a) between the main shaft (5) and the intermediate shaft (6).
A vehicular transmission is provided with an improved rotary countershaft assembly (100) that eliminates the prior art practice of securing countershaft gears (10) and (12) to adjacent sections (S.sub.1) and (S.sub.2) of a countershaft (2) by separate keys (14) and (22) disposed in separate grooves (16) and (19) respectively by a singular key (26) disposed in a groove (16) and whose radial thickness is adapted to enable countershaft gear (12) to rotate countershaft (2) in the absence of groove (19).
A motor vehicle countershaft type transmission (100) is provided in which a rotary shim member (200) is employed to rotationally advance through a threaded opening (39) in an external cover plate (38) to engage and minimize end-play of the countershaft to the extent desired and then be releasably locked at the selected rotational position by a retainer (40) having one end that engages a depression (30) in the exposed end of shim member (200) and an opposite end that is releasably secured to cover plate (38).
