| 摘要 |
A multiple countershaft transmission including a housing containing at least two countershafts having parallel axes of rotation and being fixed against all movement except rotative with respect to the housing. The housing mounts an input shaft and a mainshaft having a common axis of rotation. The input shaft is free to rotate relative to the mainshaft. The input shaft and mainshaft are fixed against all movement except rotative with respect to the housing. The input shaft mounts an input gear for rotative movement therewith. The mainshaft extends through and mounts a plurality of mainshaft gears which are free to rotate with respect to the mainshaft. The rotational axes of the countershafts are parallel to, equidistant from, and preferably symmetrically spaced about the common input shaft, mainshaft rotational axis. Each mainshaft gear and the input gear meshes with an axially aligned gear on each countershaft. The gear tooth count within each set of axially aligned countershaft gears is identical. The mainshaft is selectively clutchable to the mainshaft gears and the input gear one at a time for rotative movement therewith. An appropriate level of spline lash is used to accommodate inevitable gear timing variations in the assembled transmission due to part manufacturing tolerances without gear tooth mesh interference. The input countershaft gears are coupled to the remainder of the countershaft assemblies by torsionally resilient shafts to ensure substantially balanced distribution of torque on each countershaft as each countershaft assembly drives a clutched mainshaft gear. Adjustment is provided to rotationally index the input countershaft gears to the remainder of the countershaft assemblies. Synchromesh clutches can be employed to facilitate smooth gear engagement.
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