A shovel includes a lower traveling body, an upper rotating body mounted on the lower traveling body, an internal-combustion engine including a supercharger and being controlled at a constant revolution speed, a hydraulic pump coupled to the internal-combustion engine, a hydraulic actuator to be driven by a hydraulic oil discharged from the hydraulic pump, a control valve system including multiple flow control valves for controlling a flow of the hydraulic oil discharged from the hydraulic pump, and a controller that controls an absorbing horsepower of the hydraulic pump. The controller is configured to increase a boost pressure of the supercharger before a load is applied to the hydraulic actuator by controlling a specific flow control valve in the control valve system to limit or block the flow of the hydraulic oil discharged from the hydraulic pump and thereby increasing a discharge pressure of the hydraulic pump.

A control system may receive sensor data indicative of respective fluid levels of two or more hydraulic accumulators configured to operate at respective target fluid levels within a hydraulic system. The control system may determine respective errors of the hydraulic accumulators based on the respective fluid levels and respective target fluid levels of the hydraulic accumulators. The respective errors may correspond to pressure errors, fluid volume errors, or other types of errors of the hydraulic accumulators. Responsive to determining the respective errors, the control system may determine that the error of a given hydraulic accumulator is greater than errors of the other hydraulic accumulators and provide instructions to control a hydraulic valve to supply fluid from a single pump of the hydraulic system to the given hydraulic accumulator.

An auxiliary power unit system for mobile service vehicles is provided that can provide DC power to DC-powered equipment. The system attaches to the power take-off port of the transmission and can provide power to the DC-powered equipment without idling the engine of the mobile service vehicle, thereby reducing fossil fuel consumption and engine exhaust emissions.

A hydraulic work machine is provided in which left and right hydraulic motors are driven independently of each other by two hydraulic pumps and in which an anomaly of any of the left and right track devices can be detected with high accuracy. The hydraulic work machine includes a first pressure sensor 13 configured to detect a first pump pressure that is a delivery pressure of a first hydraulic pump 11 and a second pressure sensor 23 configured to detect a second pump pressure that is a delivery pressure of a second hydraulic pump 21. When a controller 2 decides, from detection results of a travel operation detector 5 and work operation detectors 3 and 4, that a work implement 103 is not operated but travel operation devices 6 and 7 are operated and besides left and right track devices 50 and 60 are straightly traveling, the controller 2 calculates an anomaly decision evaluation value based on a pressure difference value obtained by subtracting one from the other of the first pump pressure and the second pump pressure and decides, based on a result of comparison between the anomaly decision evaluation value and a predetermined decision reference value 84, that one of the left and right track devices has an anomaly.

A hydraulic system comprises: a hydraulic pump that includes an swash plate; an swash plate angle sensor for measuring the angle of the swash plate; an swash plate driving piston for moving the swash plate of the hydraulic pump in response to changes in pressure applied to a large diameter section; an swash plate control hydraulic line for supplying the large diameter section with a portion of the hydraulic oil discharged by the hydraulic pump; a control valve that controls the flow rate of the hydraulic oil that is following into and out of the large diameter section; an electro-proportional pressure reducing valve for producing pilot pressure that is to be transmitted to one side of the control valve; and a control device for controlling the electro-proportional pressure reducing valve according to an operation signal of an operation device and the angle information from the swash plate angle sensor.

Apparatus and methods for metering fluid to a fluid actuator. An example apparatus may include a hydraulic actuator, a fluid chamber, and a hydraulic directional control valve. The fluid chamber may include a piston slidably movable between first and second ends of the fluid chamber and dividing the chamber into first and second chamber portions. The hydraulic directional control valve may direct a fluid from a fluid source into the first chamber portion to cause a volume of fluid to be discharged out of the second chamber portion into the hydraulic actuator to actuate the hydraulic actuator by a distance corresponding to the volume of fluid received by the hydraulic actuator.

A flow divider assembly for use with a hydraulic pump provides fluid flow to separate drive motors for use in a vehicle or other application. Flow may be provided alternatively to a first fluid side and second fluid side. First and second flow divider motors are in communication with an output of a shuttle valve. A first bypass valve is connected to the first fluid side and a second bypass valve is connected to the second fluid side, and both bypass valves have an open position and a closed position. A multi-position, pilot operated valve is operably connected to both flow divider motors and to both bypass valves. An embodiment permits the output of the system to be driven in either forward or reverse directions.

A servo-control. The servo-control comprises at least one body as well as a power shaft and a control piston arranged in each body, the at least one body and the power shaft respectively forming two power members. One of the power members bears at least on end-stop member and the power member without an end-stop member bears a passivation actuator. The passivation actuator comprises a passivation shaft which bears an end-stop and a passivation piston, the passivation piston being arranged to be mobile in longitudinal translation in an enclosure, an elastic system being arranged between the passivation piston and the enclosure.

The disclosure relates to a hydraulic system including a reversing pump which has two delivery connections via which a hydraulic medium can be delivered from a tank in opposite delivery directions in order to hydraulically actuate an actuating element and supply a cooling and/or lubricating system. The hydraulic system also includes a valve assembly via which an actuating piston in a double-acting actuating cylinder can be supplied with hydraulic medium.

A first delivery connection of the reversing pump is fluidly connected to a first pressure connection of the double-acting actuating cylinder. A second delivery connection of the reversing pump is fluidly connected to a second pressure connection of the double-acting actuating cylinder. The actuating piston is mechanically coupled to a valve piston of a valve, and the valve piston is mechanically coupled to a locking device and to the actuating element.

A hydraulic control device for an automatic transmission, the hydraulic control device including: a first layer having a first parting surface and a plurality of first grooves formed in the first parting surface; and a second layer that has a second parting surface and a plurality of second grooves formed in the second parting surface and facing the plurality of first grooves, and that is stacked on the first layer in a stacking direction with the second parting surface facing the first parting surface of the first layer, so that the plurality of first grooves and the plurality of second grooves form a plurality of first oil passages.