Control valves 100f, 100g, and 100h that reduce flow passage areas of parallel hydraulic fluid lines 41f, 41g, and 41h respectively when operating devices 34a, 34b for traveling are operated, are each disposed in the parallel hydraulic fluid line 41f, 41g, or 41h so that if saturation occurs during combined operations control likely to generate a significant difference in load pressure between any two actuators, the control valve prevents full closing of a pressure compensating valve lower in load pressure and thus prevents a slowdown and stop of the actuator undergoing the lower load pressure, and so that if saturation occurs during combined operations control likely to generate a particularly significant difference in load pressure between any two actuators, the control valve ensures a necessary supply of hydraulic fluid to the actuator higher in load pressure, thereby preventing a slowdown and stop of the actuator higher in load pressure.

An independent metering valve circuit includes an actuator, a set of independent metering valves, an independent metering valve pre-compensator, an inverse resolver, and a signal conditioning element. The set of independent metering valves are fluidly coupled to the actuator and configured to independently control a flow of a hydraulic fluid to the actuator. The independent metering valve pre-compensator is configured to control the flow of the hydraulic fluid to the set of independent metering valves. The inverse resolver is configured to receive a first pressure signal from the independent metering valve circuit and a second pressure signal from a load-sense hydraulic system and output a third pressure signal. The signal conditioning element is configured to receive the third pressure signal and output a forth pressure signal configured to control a pump fluidly coupled to the load-sense hydraulic system and the independent metering valve circuit.

According to one embodiment, an actuator includes a plurality of channel members each having at least one first port into which fluid flows and at least one second port from which the fluid flows out. At least one of the channel members includes a different number of second ports from a number of first ports. The channel members are joined with each other to form at least one channel component.

Systems and apparatuses include a primary hydraulic pump including a primary displacement actuator and a primary pressure port, a primary load sense system fluidly coupled to the primary displacement actuator, a secondary hydraulic pump including a secondary displacement actuator and a secondary pressure port, a secondary load sense system fluidly coupled to the secondary displacement actuator, and a crossover pressure controller coupled between the primary pressure port and the secondary pressure port and including: a selectively energizable crossover pressure solenoid, and a crossover pressure spool movable by the crossover pressure solenoid between a combined pressure position providing fluid communication between the primary pressure port and the secondary pressure port, and a separate pressure position inhibiting fluid communication between the primary pressure port and the secondary pressure port.

An energy recovery system for a machine having a movable work tool, a swing motor to swing the work tool about a vertical axis, a pump providing pressurized fluid to the swing motor, a power source outputting power to drive the pump, and a controller. The energy recovery system may include a first accumulator, a swing charge valve selectively connecting the swing motor to the first accumulator, an assist motor operatively connected to the power source, and a discharge selectively connecting the first accumulator to the assist motor. The swing charge valve may fluidly connect the swing motor to the first accumulator when fluid pressure from the swing motor is greater than a charge set pressure. The controller may cause the discharge valve to fluidly connect the first accumulator with the assist motor when the power demand on the power source is greater than a minimum assisted power demand.

Provided is a construction machine on which a hydraulic closed circuit for driving a single rod-type hydraulic cylinder and a swing hydraulic motor is mounted and that has good swing deceleration responsiveness. In this construction machine that drives each of a single rod-type hydraulic cylinder and a swing hydraulic motor in a closed circuit, a minimum passage area from a second flushing valve to a tank in a case the second flushing valve is fully open is smaller than a minimum passage area from a first flushing valve to the tank in a case the first flushing valve is fully open.

When hydraulic fluid discharged from a hydraulic actuator is to be recovered for driving a different hydraulic actuator, the recovery frequency is increased to achieve further energy saving. To this end, a pressure increasing circuit 36 is provided in which a communication pressure increasing valve 12 is disposed in a communication passage 26 that connects a bottom side line 23 of and a rod side line 24 a boom cylinder 4. A recovery control valve 11 is controlled such that, when a first operation unit 5 is operated in a boom lowering direction (own weight falling direction of the boom) and a second operation unit 6 is operated simultaneously, only if the pressure at the bottom side of the boom cylinder 4 is higher than the pressure at the arm cylinder side that is a recovery destination of hydraulic fluid, the recovery control valve 11 is opened to recover the flow rate discharged from the bottom side of the boom cylinder 4 to the arm cylinder side.

A series hydraulic hybrid system for a vehicle may have: a hydraulic circuit with a first hydraulic displacement unit in fluid communication with a second hydraulic displacement unit, a hydraulic actuator, and a hydraulic accumulator assembly. The hydraulic accumulator assembly is selectively in fluid communication with the hydraulic circuit via at least one controllable circuit valve. The hydraulic accumulator assembly is selectively in fluid communication with the hydraulic actuator via at least one controllable actuator valve, such that the hydraulic accumulator assembly is configured to be selectively fluidly connected with and to be selectively fluidly disconnected from the hydraulic actuator via the at least one actuator valve independently of a control position of the at least one circuit valve. A method of operating the system is also described.

Provided is a hydraulic shovel capable of moving a boom, an arm, and a bucket at respective adequate speeds even during complex operations thereof, without a significant pressure loss. This hydraulic shovel includes: a first pump (31) connected to a boom actuator (24) and a bucket actuator (28); a second pump (32) connected to an arm actuator (26) and the boom actuator (24); a third pump (33) connect to the arm actuator (26); a boom control valve (54) interposed between the first pump (31) and the boom actuator (24); an arm control valve (56) interposed between the second pump (32) and the arm actuator (26); a bucket control valve (58) interposed between the first pump (31) and the bucket actuator (28); a boom merging valve (55) for speed increase interposed between the second pump (32) and the boom actuator (24); and an arm merging valve (57) for speed increase interposed between the third pump (33) and the arm actuator (26).

In a compressed air supply system for a first compressed air consumer circuit such as an air spring system of a vehicle, a first compressed air line leads to the first compressed air consumer circuit and a distribution line leads to further consumer circuits. A priority valve arrangement is disposed between the first compressed air line, wherein the first compressed air line comprises no safety valve. The first compressed air consumer circuit can therefore be filled at a higher priority, and achieve operational readiness quickly in air spring processes such as lifting or raising activities.