Patent ID: 9139982
Filing Date: 2015-09-22
Classification: E02F,F15B

Abstract:
1. A hydraulic control system, comprising: a pump configured to pressurize fluid; a motor driven by a flow of pressurized fluid from the pump, the motor including a first passage and a second passage in fluid communication with opposing sides of an impeller, wherein fluid flow into the first passage and out of the second passage corresponds with rotation of the impeller in a first direction, and fluid flow into the second passage and out of the first passage corresponds with rotation of the impeller in a second direction opposite the first; an accumulator configured to receive pressurized fluid discharged from the motor and selectively supply pressurized fluid to the motor; a makeup passage between the first and second passages of the motor, and at least a first makeup valve and a second makeup valve positioned in the makeup passage, and a low-pressure passage in fluid communication with a low pressure tank and connected to the makeup passage in between the first and second makeup valves and configured to allow fluid to flow through at least one of said first and second makeup valves into at least one of said first and second passages from the low-pressure passage when the pressure in the at least one of said first and second passages is less than the pressure in the low-pressure passage; and a control valve configured to regulate fluid flow from the pump to the motor and from the motor to the low-pressure tank via the first and second passages, the control valve including a third makeup valve in fluid communication with the first passage and a fourth makeup valve in fluid communication with the second passage, the third and fourth makeup valves each connected in parallel to respective first and second drain elements, between a drain passage and the respective first and second passages, with the drain passage connected to the low-pressure tank.