US Patent 9574582 Hydraulic pump system and method of operation

A fluid management system includes a hydraulic main pump fluidly connected to a load, an accumulator fluidly connected to the hydraulic main pump, a secondary pump, a fluid preparation system fluidly connected between an outlet of the secondary pump and an inlet of the hydraulic main pump, a reservoir, and a valve system fluidly connecting the reservoir, an outlet of the hydraulic main pump, and the secondary pump inlet. The system is at least operable between a run mode, wherein the secondary pump and accumulator cooperatively maintain the pressure within the hydraulic main pump, and a charging mode, wherein the secondary pump pumps fluid into the accumulator until a threshold volume is reached.