Patent ID: 7237642

Claim:
A frame structure of a vehicle comprising a flywheel housing, an intermediate housing and a transmission case that are connected to each other along a longitudinal axis of the vehicle to constitute a vehicle frame with an inner space for accommodating a running-power transmission path for transmitting power from an engine to sub drive wheels and main drive wheels respectively located closer to a first end and a second end along the longitudinal axis of the vehicle via a HST unit: wherein the flywheel housing has a first end and a second end along the longitudinal axis of the vehicle, the first end being connected to the engine, the second end being provided with an opening; the intermediate housing is a hollow shape having a first end and a second end along the longitudinal axis of the vehicle, the first end of the intermediate housing being provided with an abutting surface located opposite to the second end of the flywheel housing, a support surface located radially inward of the abutting surface so as to support the HST unit and a first-end opening located radially inward of the support surface, the second end of the intermediate housing being provided with a second-end opening, the abutting surface and the support surface being located in the longitudinal axis of the vehicle so that at least a portion of the HST unit is accommodated within the flywheel housing; a sub-axle drive shaft for transmitting driving power toward the sub drive wheels is disposed at lower portions within the flywheel housing and the intermediate housing so as to extend along the longitudinal axis of the vehicle; the HST unit includes a pump shaft operatively connected to the engine, a hydraulic pump unit driven by the pump shaft, a hydraulic motor unit that non-stepwisely changes a driving force from the engine in cooperation with the hydraulic pump unit, a motor shaft rotated by the hydraulic motor unit, and a center section forming a hydraulic circuit for fluidly communicating the hydraulic pump unit and the hydraulic motor unit; the center section has a first side in the longitudinal axis of the vehicle forming a pump support surface which supports the hydraulic pump unit, and a second side in the longitudinal axis of the vehicle forming a motor support surface which supports the hydraulic motor unit; the pump shaft is disposed upwardly than the motor shaft, and extends along the longitudinal axis of the vehicle such that its first end extends within the flywheel housing so as to be operatively connected to the engine and its second end extends toward the second end of the vehicle through the center section; and the motor shaft extends along the longitudinal axis of the vehicle within the intermediate housing such that its second end extends toward the second end of the vehicle, and is displaced to one side in the vehicle width direction from a line connecting the sub-axle drive shaft and the pump shaft.