A fluid pressure control device for a power shovel includes: a first switching valve configured to permit or prohibit communication between a first pump and a first cylinder; a second switching valve configured to permit or prohibit communication between a second pump and a second cylinder; a third pump configured to allow to supply working fluid to the first cylinder and the second cylinder; a first junction control valve configured to permit or prohibit communication between the third pump and the first cylinder or the second cylinder; and a communication control valve configured to prohibit communication between the third pump and the first cylinder to guide the working fluid discharged by the third pump to the second cylinder by controlling the first junction control valve in a case where the second pump is communicated with the second cylinder by the second switching valve regardless of whether or not the first pump is communicated with the first cylinder by the first switching valve.

A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, an engine provided in the upper turning body, a hydraulic pump and a hydraulic oil tank provided in the upper turning body, a plurality of hydraulic actuators driven by the hydraulic pump, and a hydraulic circuit connected to the hydraulic pump, wherein the hydraulic circuit includes a plurality of control valves configured to control flows of hydraulic oil between the hydraulic pump and the plurality of hydraulic actuators, and a unified bleed-off valve configured to collectively control bleed-off flowrates of the plurality of control valves, wherein the hydraulic circuit is configured so that a discharge pressure of the hydraulic pump becomes equal to or less than a predetermined pressure during start-up of the engine.

The present disclosure relates to an implement connectable to a working vehicle. The implement includes an arm, a fastening arrangement arranged at a first part of the arm, and an attaching arrangement connected to a second part of the arm. The fastening arrangement is connectable to the working vehicle. The attaching arrangement is attachable to a working tool. The implement further includes a first hydraulic circuit configured to carry hydraulic fluid to at least one first hydraulic function and a local control element. The implement further includes a digital interface to the working vehicle. The local control element is arranged to receive an operator control signal via said digital interface for operator control of the at least one first hydraulic function.

A work machine, preferably a mobile work machine, has an attachment device, in particular a trench cutter. The attachment device has at least two adjustable hydraulic motors for driving independent, individually controllable loads. The hydraulic supply of the adjustable hydraulic motors takes place by a hydraulic drive unit arranged externally from the attachment device, in particular by a drive unit of the work machine. The at least two adjustable hydraulic motors of the attachment device are connected to a constant pressure network provided by the hydraulic drive unit.

Disclosed is a hydraulic system for performing land preparation works by means of a simultaneous boom-up and arm-in operation. The hydraulic system according to the present invention includes: an arm cylinder and a boom cylinder that are connected to first and second hydraulic pumps, respectively; a first boom control valve that is disposed in the discharge flow path of the second hydraulic pump; a second boom control valve that is disposed in the discharge flow path of the first hydraulic pump and causes the working fluid of the first hydraulic pump to converge with the working fluid which is supplied from the second hydraulic pump to the boom cylinder; a first arm control valve that is disposed in the discharge flow path of the first hydraulic pump; a second arm control valve that is disposed in the discharge flow path of the second hydraulic pump and causes the working fluid of the second hydraulic pump to converge with the working fluid which is supplied from the first hydraulic pump to the arm cylinder; a recycle valve that is disposed in the flow path between the working fluid inlet port of the first arm control valve and a hydraulic tank; and a second boom control valve spool having a parallel pressure section in which the boom-up pilot pressure does not increase with respect to the boom-up strokes during the simultaneous boom-up and arm-in operation.

The invention relates to a hydraulic positioning device for an agricultural implement, wherein preferably a uniform movement of several hydraulic cylinders is achieved by using a progressive distributor.

A hydraulic system for controlling at least one steerable caster wheel of an agricultural machine includes a first actuator having a piston and including an inboard fluid port for supplying fluid to a first side of the piston to move the piston in a first direction, and an outboard fluid port for supplying fluid to a second side of the piston to move the piston in a second direction. A first fluid pressure equalizer is fluidically coupled to the first side actuator and operable to equalize fluid pressure over a period of time between the first side and the second side of the piston of the first side actuator.

A hydraulic system includes a first hydraulic device to be operated by an operation fluid, a second hydraulic device, the second hydraulic device being configured to be operated by the operation fluid, a first control valve to control the first hydraulic device, a second control valve disposed on a downstream side of the first control valve and configured to control the second hydraulic device, a communication tube connecting the first hydraulic device to the first control valve, the communication tube being configured to supply a return fluid that returns from the first hydraulic device to the first control valve, a supply fluid tube connecting the first control valve to the second control valve and being configured to supply the return fluid to the second control valve, and a connection fluid tube disposed on the first control valve, the connection fluid tube connecting the communication tube to the supply fluid tube.

A hydraulic lifting device for a chassis of a mobile device has a valve block, a pump, a tank, a first cylinder device and a second cylinder device. The first cylinder device and the second cylinder device can be selectively pressurized by the pump or connected to tank via the valve block. The first cylinder device is connected to the pump via at least one primary non-return valve disposed in the valve block. The second cylinder device is connected to the pump via at least one secondary non-return valve disposed in the valve block. The valve block has at least one pressure accumulator downstream of the at least one secondary non-return valve in the flow direction from the pump to the second cylinder device. Furthermore, a chassis with such a lifting device and to a mobile device with a chassis is provided.

To provide a construction machine that can highly precisely control branch flows from a hydraulic pump to a plurality of hydraulic actuators without being affected by load conditions. A controller (100) has a meter-out valve control section (140) configured to calculate a target opening area of a second meter-out valve (65a) (65b) according to a pressure difference between a supply pressure and a second meter-in pressure, or calculate a target opening area of a first meter-out valve (55a) (55b) according to a pressure difference between the supply pressure and the first meter-in pressure.