Patent ID: 8096781

Claim:
A machine hydraulic pump system, comprising: at least one hydraulic pump having an inlet fluidly connected to a drainage sump, the at least one hydraulic pump driven to pressurize a hydraulic fluid provided from the drainage sump and configured to circulate said pressurized hydraulic fluid through a hydraulic circuit, said at least one hydraulic pump including a pump casing defining an interior cavity adapted to hold a lubricating liquid, said lubricating liquid having a temperature; an upper drain port fluidly connecting the interior cavity with the drainage sump such that said lubricating liquid at an overflow level in the interior cavity drains to the drainage sump; a lower drain port in fluid communication with said interior cavity, the lower drain port disposed to fluidly connect the interior cavity with the drainage sump such that said lubricating liquid at a lower fluid level, which is below the overflow level, drains to the drainage sump; and a selectively activatable flow control member disposed in operative relation to said lower drain port, said selectively activatable flow control member adapted to move from a fluid containment condition to a fluid withdrawal condition in response to said temperature dropping below a predefined lower limit to at least partially evacuate said lubricating liquid from said interior cavity to the drainage sump prior to startup of said at least one hydraulic pump.