Patent ID: 7168247
Filing Date: 2007-01-30
Classification: F04B,F04F,F16D

Abstract:
1. A hydraulic drive device comprising: a housing comprising a main sump; a hydrostatic transmission mounted in the main sump and comprising a hydraulic pump and a hydraulic motor connected together through porting, and the porting comprises a first pressure side connecting the hydraulic pump and the hydraulic motor and a second pressure side connecting the hydraulic pump and the hydraulic motor, wherein during operation of the hydrostatic transmission, one of the pressure sides is at low pressure and the other pressure side is at high pressure; a charge sump hydraulically connected to the hydrostatic transmission; and a charge pump hydraulically connected to the charge sump and comprising a first opening proximate to only the first pressure side and a second opening proximate to only the second pressure side, wherein the charge pump is capable of providing charge fluid only to the second pressure side.