Abstract: A hydraulic circuit is disclosed. The hydraulic circuit may have a pump, a motor, a tank, and an accumulator. The hydraulic circuit may also have a valve movable between a first position at which an output of the pump is fluidly connected to the tank and the accumulator is fluidly connected to the motor, and a second position at which the output of the pump is fluidly connected to the motor.

Abstract: A hydraulic fan circuit includes a primary pump, a motor fluidly connected to the primary pump, and a fan operably connected to and driven by the motor. The circuit also includes a supply passage extending from the primary pump to the motor, a return passage extending from the motor to the primary pump, and a pressure limiting valve configured to selectively reduce pressure of a flow of pilot fluid directed to the primary pump. The circuit further includes an override valve configured to selectively connect the supply passage to the pressure limiting valve.

Abstract: A hydraulic fluid system for a mobile machine includes a closed loop hydraulic fan circuit. The hydraulic fan circuit includes a primary pump, a motor fluidly connected to the primary pump, and a fan driven by the motor. The hydraulic fan circuit also includes a supply passage extending from the primary pump to the motor, a return passage extending from the motor to the primary pump, and a first accumulator selectively fluidly connected to at least one of the supply and return passages via a charge valve. The hydraulic fluid system also includes at least one open loop hydraulic circuit fluidly connected to the first accumulator.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a tank, a pump, a swing motor having a first chamber and a second chamber, and at least one control valve configured to control fluid flow between the pump, the swing motor, and the tank. The hydraulic system may also have an accumulator configured to selectively receive pressurized fluid discharged from the swing motor and selectively supply pressurized fluid to the swing motor and a controller. The hydraulic control system may further include a first valve and a second valve coupled between the accumulator and the first and the second chambers of the swing motor. One of the first or second valve moves between a first position, a second position, and a third position for selective charging and discharging of the accumulator. The second valve also moves between multiple positions to realize selective charging and discharging of the accumulator.

Abstract: A machine is disclosed. The machine can include a frame and ground engaging propulsion elements coupled with the frame. A hydraulically actuated implement system can be coupled with the frame, and can include a linkage configured to couple with an implement, a hydraulic actuator coupled with the linkage and the frame, and a ride control and downforce control circuit configured to implement a ride control mode and a downforce control mode. The ride control mode can be configured to maintain a pressure of hydraulic fluid in the hydraulic actuator at a ride control pressure, and the downforce control mode can be configured to maintain the pressure of hydraulic fluid in the hydraulic actuator at a downforce control pressure to oppose the weight of the linkage and the implement such that the implement engages a substrate with a predetermined down force pressure which is proportionate to the downforce control pressure.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a first pump, a boom cylinder, and a first closed loop fluidly connecting the first pump to the boom cylinder. The hydraulic system may also have a second pump, a swing motor, and a second closed loop fluidly connecting the second pump to the swing motor. The hydraulic system may further have a third pump, an auxiliary actuator, and a third closed loop fluidly connecting the third pump to the auxiliary actuator. The hydraulic system may additionally have a combining valve configured to selectively connect the second closed loop to the first closed loop during a boom raising operation, and a control valve configured to selectively connect the third closed loop to the first closed loop during a boom lowering operation.

Abstract: A hydraulic pump control circuit may include a pressure reducing valve selectively operable to limit the amount of fluid pressure available to an actuator operably coupled to a pump displacement volume adjusting mechanism of a variable displacement pump. The pump may be hydraulically coupled to a motor configured to provide a torque output. The reduced pressure to the actuator limits actuator travel, thereby limiting pump displacement. Accordingly, torque output of the motor may be reduced, thereby improving traction control.

Abstract: A method for charging an accumulator is disclosed. The method includes pumping pressurized fluid from an output port of a hydraulic pump to the accumulator to charge the accumulator, and flowing makeup fluid from a hydraulic actuator system to an input port of the hydraulic pump.

Abstract: A hydraulic circuit is provided. The hydraulic circuit includes a primary pump, a displacement actuator, a charge pump, a direction control valve, and a pressure control valve. The displacement actuator is associated with the primary pump. The charge pump is configured to generate a flow of a pilot fluid. The direction control valve is configured to control the flow of the pilot fluid to the displacement actuator to affect a movement direction of the displacement actuator. The pressure control valve is configured to control a pressure of the pilot fluid to affect a movement amount of the displacement actuator. Further, the hydraulic circuit includes a controller. The controller is configured to control the direction and the pressure control valves to adjust a displacement of the primary pump based at least on one of a sensed engine parameter or a mode of operation of the primary pump.

Abstract: A hydraulic system for a machine is disclosed. The hydraulic system may have a pump configured to pressurize fluid, a swing motor driven by pressurized fluid to swing a body of the machine relative to an undercarriage, and a first circuit fluidly connecting the pump to the swing motor. The hydraulic system may also have an energy recovery motor mechanically connected to the swing motor, at least one accumulator, and a second circuit fluidly connecting the at least one accumulator to the energy recovery motor.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a unidirectional variable displacement first pump, a first actuator connected to the first pump via a closed-loop first circuit, and a first switching valve disposed between the first actuator and the first pump. The first switching valve may be configured to control a fluid flow direction through the first actuator. The hydraulic system may also have a second actuator connected to the first pump in parallel with the first actuator via the first circuit, and a second switching valve disposed between the second actuator and the first pump. The second switching valve may be configured to control a fluid flow direction through the second actuator. The hydraulic system may further have a modulation valve associated with the first circuit and configured to selectively modulate a pressure of the first circuit during actuation of the first or second switching valves.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a plurality of pumps with unidirectional functionality and being variable displacement, a common discharge passage connected to the plurality of pumps, and a common intake passage connected to the plurality of pumps. The hydraulic system may also have at least one actuator connected in closed-loop manner to the common discharge and common intake passages, and a switching valve associated with the at least one actuator and disposed between the at least one actuator and the common discharge and intake passages. The hydraulic system may additionally have at least one isolation valve configured to selectively isolate a portion of the common discharge passage and a portion of the common intake passage associated with one pump of the plurality of pumps from another pump of the plurality of pumps.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a unidirectional variable displacement first pump, a first hydraulic actuator connected to the first pump via a closed-loop first circuit, a unidirectional variable displacement second pump, and a second hydraulic actuator connected to the second pump via a closed-loop second circuit. The hydraulic system may also have a third pump selectively connectable in closed-loop manner to the first or second circuits, and a first valve disposed between the first hydraulic actuator and the first pump and configured to selectively direct fluid from the first circuit to the second and third pumps.

Abstract: A hydraulic system is disclosed having first, second, and third pumps. The hydraulic system may also have a first actuator connected to the first pump in closed-loop manner, a second actuator connected to the second pump in closed-loop manner, and a third actuator. The hydraulic system may further have a selector valve associated with the third pump, and a first switching valve associated with the third pump and the third actuator. The first switching valve may be movable between a first position at which the third pump is connected to the third actuator in a closed-loop manner to move the third actuator in a first direction, a second position at which the third pump is connected to the third actuator in a closed-loop manner to move the third actuator in a second direction, and a third position at which the third pump is connected to the selector valve.

Abstract: A method for estimating a fluid charge of a hydraulic accumulator includes determining a first accumulator pressure at a first time with a pressure sensor, the first time during accumulator charging; determining a second accumulator pressure at a second time with the pressure sensor, the second time during accumulator charging; determining a first fan speed at the first time; determining a second fan speed at the second time; and estimating the fluid charge of the hydraulic accumulator as a function of the first accumulator pressure, the second accumulator pressure, the first fan speed, and the second fan speed.

Abstract: A hydraulic circuit is disclosed. The hydraulic circuit may have a pump, a motor, a tank, and an accumulator. The hydraulic circuit may also have a valve movable between a first position at which an output of the pump is fluidly connected to the tank and the accumulator is fluidly connected to the motor, and a second position at which the output of the pump is fluidly connected to the motor.

Abstract: An engine system includes an engine, a primary pump coupled to the engine, and a motor fluidly connected to the primary pump. The engine system further includes a heat exchanger fluidly connected to the engine, the heat exchanger configured to accept heated coolant from the engine and deliver cooled coolant to the engine. The engine system also includes a fan driven by the motor in either a forward or a reverse mode of operation, the fan configured to pull air toward the heat exchanger in a first direction during the forward mode of operation to assist in cooling the coolant, and to push air toward the heat exchanger in a second direction opposite the first direction during the reverse mode of operation. The engine system further includes a controller configured to operate the fan in the reverse mode of operation in response to a sensed temperature of the coolant and a speed of the fan in the forward mode of operation.

Abstract: A hydraulic fan circuit includes a primary pump, a motor fluidly connected to the primary pump, and a fan operably connected to and driven by the motor. The circuit also includes a supply passage extending from the primary pump to the motor, a return passage extending from the motor to the primary pump, and a pressure limiting valve configured to selectively reduce pressure of a flow of pilot fluid directed to the primary pump. The circuit further includes an override valve configured to selectively connect the supply passage to the pressure limiting valve.

Abstract: A hydraulic fluid system for a mobile machine includes a closed loop hydraulic fan circuit. The hydraulic fan circuit includes a primary pump, a motor fluidly connected to the primary pump, and a fan driven by the motor. The hydraulic fan circuit also includes a supply passage extending from the primary pump to the motor, a return passage extending from the motor to the primary pump, and a first accumulator selectively fluidly connected to at least one of the supply and return passages via a charge valve. The hydraulic fluid system also includes at least one open loop hydraulic circuit fluidly connected to the first accumulator.

Abstract: A hydraulic fan circuit is disclosed. The hydraulic fan circuit may have a primary pump, a high-pressure passage fluidly connected to the primary pump, and a low-pressure passage fluidly connected to the primary pump. The hydraulic fan circuit may also have at least one accumulator in selective fluid communication with at least one of the high- and low-pressure passages, a motor, and a fan connected to the motor. The hydraulic fan circuit may further have a fan isolation valve fluidly connected to the high- and low-pressure passages. The fan isolation valve may be movable between a flow-passing position at which the motor is fluidly connected to the primary pump via the high- and low-pressure passages, and a flow-blocking position at which the motor is substantially isolated from the primary pump.