Agricultural implements and hydraulic circuits for agricultural implements are disclosed herein. An agricultural implement includes a fluid source, a plurality of fluid demand devices, a delivery control valve, and a priority valve. The fluid source is configured to supply hydraulic fluid. The plurality of fluid demand devices are each configured to receive hydraulic fluid supplied by the fluid source during operation of the agricultural implement. The delivery control valve is fluidly coupled between the fluid source and a first fluid demand device. The delivery control valve is configured to selectively deliver hydraulic fluid supplied by the fluid source to the first fluid demand device during operation of the agricultural implement. The priority valve is fluidly coupled between the delivery control valve and the first fluid demand device.

To provide a driving device capable of improving the operability of a plurality of single rod hydraulic cylinders. The present invention takes a construction provided with a closed circuit A in which first and third hydraulic pumps 12, 14 and a boom cylinder 1 are connected through selector valves 43a, 45a in a closed-circuit fashion, a plurality of open circuits E, F provided with second and fourth hydraulic pumps 13, 15 and selector valves 44a, 46a that switch the supply destinations of hydraulic oils flowing out from the second and fourth hydraulic pumps 13, 15, and a connection passage 301 connected to sides of the selector valves 44a, 46a from which sides hydraulic oil flows out, and connected to the closed circuit A.

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller (51) controls a cap-side selector valve (46) and a rod-side selector valve (47) such that a particular open-circuit pump (15) not connected to a single rod hydraulic cylinder (3) is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve (49) provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor (7) are driven simultaneously.

This invention relates to a sectional hydraulic valve and a truck mounted forklift incorporating the distributor. The sectional hydraulic valve comprises an inlet cover, a plurality of hydraulic sections and an end cap. The hydraulic sections each having a pump gallery, a tank gallery, an A port, a B port, a spool and a remote pilot gallery. The end cap comprises a pump port coupled to the pump gallery, a tank port coupled to the tank gallery and a connecting conduit between the pump port and the tank port. The end cap further comprises a remote pilot gallery port coupled to the remote pilot gallery, a fluid passageway between the remote pilot gallery port and the connecting conduit, and a valve assembly operable to selectively permit or restrict flow of hydraulic fluid between the connecting conduit in the end cap and the remote pilot gallery in the hydraulic section.

A switching unit may be provided for connecting a first pneumatic unit and a second pneumatic unit of a pneumatic system together. The switching unit comprises a main body having: a channel structure which extends through the main body; a first and a second inlet for introducing a pressure into the channel structure; a first and a second outlet for discharging at least some of the pressure from the channel structure; and a first and a second valve; wherein the first inlet can be brought into a pressure-exchange connection to the first outlet via a first channel by setting a first switch position of the first valve or to the second outlet via a second channel by setting a second switch position of the first valve, and wherein the second inlet can be brought into a pressure-exchange connection to the first outlet via a third channel by setting a first switch position of the second valve or to the second outlet via a fourth channel by setting a second switch position of the second valve.

[Problem to Be Solved] To make it possible to control supply, discharge, and recycled flow rates independently of each other for the boom cylinder in a construction machine comprising first and second boom spool valves respectively connected to first and second hydraulic pumps. [Solution] When the boom cylinder (8) is contracted, the first boom spool valve (16) is configured to control the recycled flow rate from head side a chamber (8A) to rod side oil chamber (8B), the second boom spool valve (17) is configured to control the discharge flow rate from head side oil chamber (8A) to oil tank (15), and both first and second boom spool valves (16, 17) are configured not to supply pressure oil from first and second hydraulic pumps (11, 12) to the boom cylinder (8).

An oil pressure control device controls a supply pressure of oil supplied to an oil pressure chamber of a friction element having a first engagement board and a second engagement board engaged with or disengaged from each other between a non-engagement state and a non-sliding engagement state via a sliding engagement state. The oil pressure control device includes: an electromagnetic valve that controls the supply pressure using a spool which reciprocates according to an energizing amount; and a control part that defines a first oscillatory wave part in which the energizing amount is controlled by making a first waveform with a first frequency to superimpose on a second waveform with a second frequency higher than the first frequency during a first period while the sliding engagement state and an instruction value of the supply pressure are kept constant.

Motion of rams in fluid cylinders to drive machine parts is equalized by equalization chambers between drive chambers for equalizing outward and inward driven motion of the rams and the attached machine parts, irrespective of portions of loads and forces on the machine parts in relation to the rams. Duplicated machine parts may be closely positioned or widely separated, while providing the same controlled equalized movement irrespective of loading. The movable elements may be tilted to new angular positions before they are translated by the rams.

A control system for a hydraulic system including an accumulator and a hydraulic transformer coordinates flow sharing within the hydraulic system. The hydraulic transformer includes first and second variable displacement pump/motor units mounted on a rotatable shaft. The rotatable shaft has an end adapted for connection to a first external load. The first variable displacement pump/motor unit includes a first side that fluidly connects to a pump and a second side that fluidly connects to a tank. The second variable displacement pump/motor unit includes a first side that fluidly connects to the accumulator and a second side that fluidly connects with the tank. A second external load may be hydraulically connected to the hydraulic system. Energy may be transferred to/from the pump, the accumulator, the first external load, and/or the second external load, as directed by the control system.

A fluid circuit includes a pressure fluid source configured to supply pressure fluid, multiple actuators connected to the pressure fluid source , a direction switching valve configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source , and a discharge amount control mechanism configured to control the output pressure of the pressure fluid source such that a pressure difference ΔP between the output pressure of the pressure fluid source and the maximum load pressure of the load pressures of the multiple actuators reaches a target value ΔPt. The fluid circuit further includes an accumulator configured to accumulate part of return fluid from the actuators.