Hydraulic valve circuitry adapted for automatic weight-responsive control of load-clamping members of a load-lifting system having a free lift mast. The load-lifting system generally includes one or more fluid power actuator for applying a gripping force to a load, at least one elongate, longitudinally-extensible fluid power lifting device having a free lift range of motion and at least one main lift range of motion, and manually operated load-clamping and load-lifting selector valves. The hydraulic valve circuitry provides, independently, weight-responsive control of the load-clamping members when lifting a load, full-time automatic weight-responsive force control of the load-clamping members without concurrent manual actuation of load-clamping or load-lifting selector valves, and equalization of sensed load weight so that the sensed load weight is substantially independent of the longitudinally-extensible position of the lifting device.

A valve body comprises an inner compartment extending along a longitudinal axis from a second end portion towards a first end portion. First, second, and third fluid ports in to the valve body are perpendicular to the longitudinal axis. The second fluid port is between the third and the first fluid port. A fourth fluid port is parallel to the longitudinal axis. A spool is configured to selectively reciprocate in the inner compartment. The spool comprises a first fluid receptacle configured to block fluid flow to the third fluid port and to fluidly communicate with the second fluid port when the spool adjoins the first end portion. The first fluid receptacle is configured to fluidly communicate with the second fluid port and with the third fluid port when the spool adjoins the second end portion. A second fluid receptacle is configured to receive fluid pressure from the fourth fluid port.

The invention relates to a controlled three-way proportional valve unit comprising: a valve assembly with two individual valves; an actuating device actuating valves of the valve assembly; and a control unit acting upon the actuating device and having a control signal input, the valves of the valve assembly being designed as poppet valves arranged on opposite sides and having counter-rotatable valve spindles. The valve spindles are prestressed relative each other in opposite directions by a prestressing element such that, when the actuating unit is inactive, a first poppet valve is open and the second poppet valve is closed. The actuating device comprises an actuator common to both poppet valves, acts upon the two valve spindles and changes the position of the valve spindles counter to the effect of the prestressing element.

Hydraulic valve circuitry adapted for automatic weight-responsive control of load-clamping members of a load-lifting system having a free lift mast. The load-lifting system generally includes one or more fluid power actuator for applying a gripping force to a load, at least one elongate, longitudinally-extensible fluid power lifting device having a free lift range of motion and at least one main lift range of motion, and manually operated load-clamping and load-lifting selector valves. The hydraulic valve circuitry provides, independently, weight-responsive control of the load-clamping members when lifting a load, full-time automatic weight-responsive force control of the load-clamping members without concurrent manual actuation of load-clamping or load-lifting selector valves, and equalization of sensed load weight so that the sensed load weight is substantially independent of the longitudinally-extensible position of the lifting device.

A pump apparatus includes: a pump that ejects a hydraulic fluid; and a selector valve that switches a direction of a flow of the hydraulic fluid to be supplied to one of a first chamber and a second chamber of a cylinder apparatus, which is internally partitioned by a piston into the first chamber extending during an extending stroke of the cylinder apparatus, and the second chamber extending during a shortening stroke of the cylinder apparatus, and the selective valve has, at a channel connected to the second chamber, an orifice that is narrower than a channel connected to the first chamber.

A hydraulic control valve assembly to be integrated into a pressure compensated load sensing system including a fluid source is provided. The hydraulic control valve assembly includes a first working unit to control a first hydraulic function of a machine. The first working unit includes a first directional and return flow control in the form of a first spool, a first function flow control to selectively communicate a working pressure of the first function to the fluid source, and a first downstream flow control. The hydraulic control valve assembly further includes a second working unit arranged downstream of the first working unit. The second working unit to control a second hydraulic function of the machine. The first downstream flow control to selectively restrict a flow a fluid from the fluid source to the second working unit.

A hydraulic control valve assembly to be integrated into a pressure compensated load sensing system including a fluid source is provided. The hydraulic control valve assembly includes a first working unit to control a first hydraulic function of a machine. The first working unit includes a first directional and return flow control in the form of a first spool, a first function flow control to selectively communicate a working pressure of the first function to the fluid source, and a first downstream flow control. The hydraulic control valve assembly further includes a second working unit arranged downstream of the first working unit. The second working unit to control a second hydraulic function of the machine. The first downstream flow control to selectively restrict a flow a fluid from the fluid source to the second working unit.

A method for unloading a load on a test article in a testing system includes determining a load differential in at least one of a calculated load at a valve for an actuator of the testing system and a calculated load on a load cell coupled to the actuator. A controlled unload of the load on the test article is initiated via a system controller when the determined load differential a reaches a first level. An interlock unload of the load on the test article is performed via the valve when the determined load differential reaches a second level higher than the first level.

A pneumatic supply device for an agricultural tractor includes a compressed air source for producing a compressed air flow, a cooler for cooling the air flow produced, and a first air dryer, which is fed with the cooled air flow and via the outlet of which a first pneumatic consumer group can be supplied with dehumidified compressed air in accordance with a first dehumidification and flow capacity, and a second air dryer, which is fed with the cooled air flow and via the outlet of which a second pneumatic consumer group can be supplied with dehumidified compressed air in accordance with a second dehumidification and flow capacity.

A method and system providing a pressurized fluid includes a pump having a pump inlet and a pump outlet, the pump to provide a fluid flow, a bypass path to direct the fluid flow from the pump outlet to the pump inlet, a load path having a load path pressure, the load path including: a fluid accumulator to accumulate a fluid volume, and at least one load device, a bypass regulator valve in fluid communication with the pump outlet, the bypass path, and the load path, and a controller to direct the fluid flow to the load path in response to the load path pressure being less than a low load path threshold pressure via the bypass regulator valve and to direct the fluid flow to the bypass path in response to the load path pressure being greater than a high load path threshold pressure via the bypass regulator valve.