Patent ID: 9181964
Filing Date: 2015-11-10
Classification: F15B,F16H

Abstract:
1. A hydraulic system, comprising: a pump fluidly coupled to a reservoir that contains hydraulic fluid; a control valve fluidly coupled to the pump, the control valve being selectively movable between at least two positions; a relief valve fluidly coupled to the pump via a relief conduit, the relief valve operable to flow hydraulic fluid from an outlet of the pump to the reservoir; and a variable pressure setpoint module fluidly coupled to the relief valve and the control valve, the variable pressure setpoint module being operable to open the relief valve in response to at least two pressure setpoints depending on a position of the control valve, the variable pressure setpoint module including a first pilot valve in fluid communication with the pump via a control orifice, the first pilot valve operable to flow hydraulic fluid from the control orifice to the reservoir via an internal passage defined by the control valve when the control valve is oriented in a first position and when a pressure in the variable pressure setpoint module exceeds a first pressure, and a second pilot valve in fluid communication with the pump via the control orifice, the second pilot valve operable to flow hydraulic fluid from the control orifice to the reservoir via a second return conduit when the control valve is oriented in a second position that blocks fluid communication between the control orifice and the reservoir via the control valve and when the pressure in the variable pressure setpoint module exceeds a second pressure, the second pressure being greater than the first pressure.