Patent ID: 6488111
Filing Date: 2002-12-03
Classification: B60K,B60W,F16H

Abstract:
An hydraulic drive system for a vehicle having three independent wheel drive shaft assemblies in an essentially triangular configuration, namely a transversely arranged pair of drive shaft assemblies and a single wheel drive shaft assembly longitudinally spaced from the transversely arranged pair of drive shaft assemblies, the hydraulic drive system comprising:a hydraulic pump; three drive units, a first being a single drive unit and a second and a third being transverse drive units, each comprising a plurality of mechanically coupled hydraulically operated drives; a hydraulic input for each drive; a hydraulic output for each drive; the single drive unit forming part of the single wheel drive shaft assembly; each of the second and third transverse drive units forming part of one of the transversely arranged drive shaft assemblies; a primary hydraulic fluid line connecting the hydraulic pump to the input of each drive of the single drive unit and to one of the drives of each of the transverse drive units; a secondary fluid line connecting the output of the drive of one of the single drive units separately to the unconnected input of the drive of one of the transverse drive units; a further secondary fluid line connecting the output of the drive of the other single drive unit separately to the unconnected input of the drive of the other transverse drive unit; a return hydraulic fluid line connecting the output of each drive of the transverse drive units to the hydraulic pump; by-pass hydraulic fluid lines each connecting across each secondary hydraulic fluid line and the return hydraulic fluid lines; an on/off diverter valve mounted in each by-pass hydraulic fluid line, the diverter valve in the closed position causing the drive units connected by the secondary fluid line to operate in series; means for detecting movement of the vehicle out of in line travel; and means for operating the on/off diverter valves over a predetermined delay to cause the drive of the single drive shaft assembly connected to the drive of the transverse drive unit to operate in parallel therewith upon the vehicle turning and to cause the other drive of the single drive shaft assembly to operate in series with the other transverse drive unit.