| 摘要 |
<p>A transmission for a four-wheel drive vehicle having a multi-speed geartrain (42) and power transfer mechanism (44) incorporated into a common housing assembly (45). The multi-speed geartrain includes a input shaft (46), a mainshaft (48), and a plurality of constant-mesh gearsets (50,52,54) arranged for selectively coupling the mainshaft (48) to the input shaft (46) for driven rotation at various speed ratios. The mainshaft (48) can be selectively coupled to the power transfer mechanism (44) for establishing two alternative power transmission routes. In particular, a synchronized range shift mechanism (58) is provided for establishing a high-range transmission route and a low-range transmission route from the mainshaft (48) to a primary (rear) driveline (38,14) to define a two-wheel drive mode. A portion of the drive torque delivered to the primary driveline (38,14) can be transferred automatically through a transfer clutch (60) to the secondary driveline (32,12) to establish an on-demand four-wheel drive mode. As an option, a mode clutch can be provided for permitting the secondary driveline (32,12) to be locked to the primary driveline (38,14) for establishing a part-time four-wheel drive mode.</p> |
