Transmission assembly for tractors

摘要

A bearing support frame (4) is disposed within a rear end portion of a tractor front housing (1) and is fixedly supported by this housing which has an internal partition wall (1a) and an open rear end. A transmission casing (2) having an open front end is fastened to the rear of the front housing and includes a primary speed change mechanism (14) which is disposed between a drive shaft (12) and change shaft (13). These shafts are supported at their front end portions by the support frame and extend forwardly of this frame. An additional speed change mechanism (9) is disposed within a rear half of the front housing and comprises a primary shaft (7), rotatable output member (10) and countershaft (11). The output member is fixedly mounted on a front end portion of the drive shaft, and a rear end portion of the countershaft is journaled by a front end portion of the change shaft. Preferably, the support frame includes therein an annular bore portion (4c) for temporarily holding the output member in position at a preassembled condition of the additional change mechanism in the front housing.