Abstract: First and second mechanical hydraulic valves are disposed between a pump and the cap side chamber of an actuator and the pump and the rod chamber of the pump. The first and second valves are actuated as a result of respective pressure differentials applied across the valves. A controller controls flow from a pump in response to a commanded motion to control movement of the actuator, and cause the valves to open. The valves are disposed in their no-flow positions when the pump is not operative, and when the hydraulic system of off or locked out to hold a load.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump configured to draw low-pressure fluid from one of a first and a second passage, and discharge fluid at an elevated pressure into the other of the passages. The hydraulic system may also have an actuator coupled to the pump via the first and second passages, a charge circuit, and a makeup valve movable by a pressure differential between the first and second passages to connect the charge circuit with a lower pressure one of the first and second passages. The hydraulic system may further have a first force modulation control valve configured to selectively direct fluid from the pump through the makeup valve to the second passage to bypass the actuator, and a second force modulation control valve configured to selectively direct fluid from the pump through the makeup valve to the first passage to bypass the actuator.

Abstract: A hydraulic system is disclosed having a pump configured to draw low-pressure fluid from one of a first and second passage, and discharge fluid into the other of the passages. The hydraulic system may also have an actuator coupled to the pump via the passages, a charge circuit, a makeup valve movable to pass fluid from a higher pressure one of the first and second passages, and a force modulation control valve disposed between the makeup valve and the charge circuit. The force modulation control valve may be movable between a first position at which fluid passed from the higher-pressure one of the first and second passages is directed into the charge circuit, and at least a second position at which fluid from the higher-pressure one of the first and second passages is directed into a lower-pressure one of the first and second passages and blocked from the charge circuit.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump configured to draw low-pressure fluid from one of a first passage and a second passage and discharge fluid into the other of the first and second passages, and an actuator coupled to the pump via the first and second passages. The hydraulic system may also have at least a first control valve fluidly connected between the first and second passages to selectively direct fluid from one of the first and second passages to bypass the pump and flow into the other of the first and second passages. The hydraulic system may further have at least a second control valve fluidly connected in parallel with the at least a first control valve to selectively direct fluid from one of the first and second passages to bypass the actuator and flow into the other of the first and second passages.

Abstract: A hydraulic system includes a variable-displacement first pump, a variable-displacement second pump, and a first actuator selectively connected either to the first pump in a closed loop manner and not the second pump, or to the first and second pumps in a closed loop manner. The hydraulic system also includes a second actuator selectively connected either to the second pump in a closed loop manner and not the first pump, or to the first and second pumps in a closed loop manner. The hydraulic system further includes a variable-displacement rotary actuator selectively connected either to the first pump in a closed loop manner and not the second pump, or to the first and second pumps in a closed loop manner.

Abstract: A hydraulic system includes a variable-displacement first pump, an over-center variable-displacement first travel motor selectively connected to receive fluid pressurized by the first pump in a closed loop manner, and an over-center variable-displacement second travel motor selectively connected to receive fluid pressurized by the first pump in parallel with the first travel motor in a closed loop manner. The hydraulic system also includes a linear actuator selectively connected to receive fluid pressurized by the first pump in parallel with the first and second travel motors in a closed loop manner.

Abstract: A hydraulic system hydraulic system includes a variable displacement pump, and a variable displacement first travel motor selectively fluidly connected to the pump in a closed-loop manner. The system also includes a first switching valve associated with the first travel motor and configured to selectively switch a flow direction of fluid passing through the first travel motor from the pump. The system further includes a variable displacement second travel motor selectively fluidly connected to the pump in a closed-loop manner. The system also includes a second switching valve associated with the second travel motor and configured to selectively switch a flow direction of fluid passing through the second travel motor from the pump.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a first meterless circuit with a first pump fluidly connected to a first actuator in a closed-loop manner, and a second meterless circuit with a second pump fluidly connected to a second actuator in a closed-loop manner. The hydraulic system may also have at least one accumulator configured to receive pressured fluid from and discharge pressurized fluid to the first and second meterless circuits.

Abstract: A hydraulic system includes a first pump, a first actuator fluidly connected to the first pump via a first closed-loop circuit, a second pump, and a second actuator fluidly connected to the second pump via a second closed-loop circuit. The system also includes a third pump, a third actuator fluidly connected to the third pump via a third closed-loop circuit, a fourth pump, and a fourth actuator fluidly connected to the fourth pump via a fourth closed-loop circuit. The system further includes a first combining valve configured to combine fluid from the first and second circuits, a second combining valve configured to combine fluid from the second and third circuits, and a third combining valve configured to combine fluid from the third and fourth circuits. The system also includes a fourth combining valve configured to combine fluid from the first and fourth circuits.

Abstract: A hydraulic system includes a variable-displacement first pump and a variable-displacement second pump. The hydraulic system also includes a first actuator selectively connected either to the first pump in a closed loop manner and not the second pump, to the second pump in a closed loop manner and not the first pump, or to the first and second pumps in a closed loop manner. The hydraulic system further includes a second actuator and a variable-displacement rotary actuator that are each selectively connected either to the first pump in a closed loop manner and not the second pump, to the second pump in a closed loop manner and not the first pump, or to the first and second pumps in a closed loop manner.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a plurality of closed-loop circuits fluidly connecting a plurality of pumps to a plurality of actuators, and at least one control valve configured to selectively fluidly connect a first of the plurality of closed-loop circuits to a second of the plurality of closed loop circuits. The hydraulic system may also have an accumulator configured to receive pressured fluid from and discharge pressurized fluid to at least the first of the plurality of closed-loop circuits.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump, a rotary actuator, a linear actuator, and a closed-loop circuit fluidly connecting the pump to the rotary and linear actuators. The hydraulic system may also have at least one valve configured to switch fluid flow direction from the pump through the linear actuator during fluid flow in a single direction through the rotary actuator.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump, a first actuator, and a meterless circuit connecting the first actuator to the pump. The hydraulic system may also have a second actuator connected to the meterless circuit in parallel with the first actuator.

Abstract: A hydraulic system is disclosed. The hydraulic system may have an over-center, variable-displacement pump, an actuator, and first and second passages that create a closed-loop circuit. The hydraulic system may also have first and second check valves disposed in the first and second passages, respectively, to allow flow only from the pump to the actuator. The hydraulic system may further have a first bypass line connecting the first passage at a location between the actuator and the first check valve to the first passage at a location between the first check valve and the pump, and a second bypass line connecting the second passage at a location between the actuator and the second check valve to the second passage at a location between the second check valve and the pump. The hydraulic system may additionally have a valve configured to control flow through the first and second bypass lines.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump, a hydraulic actuator, and first and second passages fluidly connecting the pump to the hydraulic actuator in a closed-loop. The hydraulic system may also have a control valve, and a load-holding valve configured to selectively lock movement of the hydraulic actuator. The load-holding valve may include a valve block at least partially defining a pump passage, an actuator passage, a control passage, a restricted passage connecting the actuator passage and the control passage, and a bypass passage connecting the actuator passage and the control passage. The load-holding valve may also include a valve element movable between a first position at which flow between the pump and the hydraulic actuator is blocked, and a second position at which fluid is allowed to flow between the pump and the hydraulic actuator, the valve element being spring-biased toward the first position.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump, a tank, a displacement actuator having first and second chambers, a regeneration valve, and a load-holding valve. The hydraulic system may also have a displacement control valve including a valve element, and a stationary cage portion at least partially forming a high-pressure passage fluidly connecting the pump and valve element, a low-pressure passage fluidly connecting the valve element and tank, a first displacement actuator passage fluidly connecting the valve element and first chamber, a second displacement actuator passage fluidly connecting the valve element and second chamber, a load-holding control passage fluidly connecting the valve element and load-holding valve, and a regeneration control passage fluidly connecting the valve element and regeneration valve.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a primary pump, a hydraulic actuator, and first and second passages fluidly connecting the primary pump to the hydraulic actuator in a closed-loop manner. The hydraulic system may also have a charge circuit, a makeup valve movable to selectively allow charge fluid from the charge circuit to enter the first or second passages, and at least one restricted pilot passage configured to direct pilot fluid to the makeup valve to move the makeup valve and allow the charge fluid into the first and second passages.

Abstract: A hydraulic system includes an actuator, a pump, rod side and cap side fluid connections between the pump and the rod and cap side chambers, respectively, at least one selectively actuatable regeneration valve that selectively provides flow from the cap side fluid connection to the rod side fluid connection, and a controller. The controller controls the pump to selectively vary the flow rate of the pump in response to a commanded motion to control movement of the piston. The controller actuates the regeneration valve during a retraction of the piston into the cylinder when pump is acting as a motor.

Abstract: First and second mechanical hydraulic valves are disposed between a pump and the cap side chamber of an actuator and the pump and the rod chamber of the pump. The first and second valves are actuated as a result of respective pressure differentials applied across the valves. A controller controls flow from a pump in response to a commanded motion to control movement of the actuator, and cause the valves to open. The valves are disposed in their no-flow positions when the pump is not operative, and when the hydraulic system of off or locked out to hold a load.