Provided is a swing-back preventing apparatus capable of preventing a hydraulic actuator in a stop state from operating by undesired load. The swing-back preventing apparatus includes a housing, a piston, and a pair of biasing members. First and second spaces are formed between the piston and the housing, and the piston includes a pair of communication passages that are communicable with first and second spaces. When the piston is located at a first offset position, the first space is blocked from a first port. When the piston separates from the first offset position, the first space is connected to the first port. When the piston is located at a second offset position, the second space is blocked from a second port. When the piston separates from the second offset position, the second space is connected to the second port. When the piston is located at a position on the first offset position side of a neutral position, a first communication passage is connected to the first space. When the piston is located in a range from the neutral position to the second offset position, the first communication passage is blocked from the first space. When the piston is located at a position on the second offset position side of the neutral position, a second communication passage is connected to the second space. When the piston is located in a range from the neutral position to the first offset position, the second communication passage is blocked from the second space.

A fluid valve has a valve plug configured as follows. In order to control a flow rate of a fluid between a first pressure chamber and a second pressure chamber, the valve plug is provided so as to be openable and closable in accordance with a difference between forces generated by pressures in the pressure chambers and resilience of an elastic member. The fluid valve includes an opening motion promoting portion. The opening motion promoting portion promotes an increase in degree of opening of the valve plug after the valve plug has been opened.

In an anti-reverse valve, a first communication passage that allows the first supply and discharge passage to communicate with the first pressure chamber and a second communication passage that allows the second supply and discharge passage to communicate with the second pressure chamber are provided inside the spool, a first restrictor is provided in the first communication passage, a second restrictor is provided in the second communication passage, and a first annular groove that allows the first supply and discharge passage to communicate with the drain passage when the spool is placed at the first communication position and a second annular groove that allows the second supply and discharge passage to communicate with the drain passage when the spool is placed at the second communication position are provided in an outer periphery of the spool.

Provided is a swing-back preventing apparatus capable of preventing a hydraulic actuator in a stop state from operating by undesired load. The swing-back preventing apparatus includes a housing, a piston, and a pair of biasing members. First and second spaces are formed between the piston and the housing, and the piston includes a pair of communication passages that are communicable with first and second spaces. When the piston is located at a first offset position, the first space is blocked from a first port. When the piston separates from the first offset position, the first space is connected to the first port. When the piston is located at a second offset position, the second space is blocked from a second port. When the piston separates from the second offset position, the second space is connected to the second port. When the piston is located at a position on the first offset position side of a neutral position, a first communication passage is connected to the first space. When the piston is located in a range from the neutral position to the second offset position, the first communication passage is blocked from the first space. When the piston is located at a position on the second offset position side of the neutral position, a second communication passage is connected to the second space. When the piston is located in a range from the neutral position to the first offset position, the second communication passage is blocked from the second space.

A return manifold includes a housing having a first workport, a second workport, a third workport, and a fourth workport, and defining a first chamber and a second chamber. The return manifold includes a back-pressure disk arranged between the first workport and the first chamber, a bypass disk arranged between the first chamber and the second chamber, a back-pressure spring biased between the back-pressure disk and the bypass disk, and a bypass spring biased against the bypass disk. The back-pressure disk and the bypass disk are hydro-mechanically coupled so that movement of the bypass disk alters a force on the back-pressure disk and movement of the back-pressure disk alters a force on the bypass disk.

A fluid valve has a valve plug configured as follows. In order to control a flow rate of a fluid between a first pressure chamber and a second pressure chamber, the valve plug is provided so as to be openable and closable in accordance with a difference between forces generated by pressures in the pressure chambers and resilience of an elastic member. The fluid valve includes an opening motion promoting portion. The opening motion promoting portion promotes an increase in degree of opening of the valve plug after the valve plug has been opened.

A hydraulic circuit with electronic latching through valve assemblies to allow full control of ground engaging tools including raising, lowering, and providing regulated active down force pressure via a work vehicle valves with manual input while allowing a continuous pressure source to be used in parallel. Pressure transducers and electrically controlled valves along with an electric control circuit allow automatic switching between manual control and automatic control of the ground engaging tools.

A hydraulic circuit with electronic latching through valve assemblies to allow full control of ground engaging tools including raising, lowering, and providing regulated active down force pressure via a work vehicle valves with manual input while allowing a continuous pressure source to be used in parallel. Pressure transducers and electrically controlled valves along with an electric control circuit allow automatic switching between manual control and automatic control of the ground engaging tools.

A pressure-balance valve for balancing the pressures of fluids admitted into the pressure-balance valve via respective second ducts. The pressure-balance valve has both a chamber for guiding movement in translation of a piston, and also fluid flow paths, each comprising a said second duct and a first duct for admitting a fluid coming from the same fluid source as the fluid flowing in its second duct. Each of the first ducts is provided with a shutter co-operating with a ramp arranged on the piston. Movement of the piston in translation as a result of a pressure difference between the fluids respectively admitted into the second ducts causes one of the shutters to slide along the corresponding ramp and consequently allows additional fluid to be delivered from a first duct to the second duct of the same fluid flow path.