There is provided a boom extending and retracting apparatus that can improve the convenience of the telescopic boom while reducing the burden on the operator. The boom extending and retracting apparatus of the crane chooses the mode of the fluid circuit between the normal fluid circuit and the differential fluid circuit to slide a plurality of boom members by one telescopic cylinder. After the operating lever is turned to an extension side and the controller starts extending the telescopic boom using the differential fluid circuit, when the operating lever is turned to the extension side again via the neutral position, the controller chooses the normal fluid circuit to extend the telescopic boom using the normal fluid circuit.

There is provided a boom extending and retracting apparatus that can improve the convenience of the telescopic boom while reducing the burden on the operator. The boom extending and retracting apparatus of the crane chooses the mode of the fluid circuit between the normal fluid circuit and the differential fluid circuit to slide a plurality of boom members by one telescopic cylinder. After the operating lever is turned to an extension side and the controller starts extending the telescopic boom using the differential fluid circuit, when the operating lever is turned to the extension side again via the neutral position, the controller chooses the normal fluid circuit to extend the telescopic boom using the normal fluid circuit.

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.

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 load-handling clamp mountable on a lift truck has one or more hydraulic clamping cylinders of the type having two or more sequentially extensible stages capable of applying either load-weight-responsive variable hydraulic load-clamping force or, alternatively, load-size-responsive variable hydraulic load-clamping force, without risking the clamp's dropping of a clamped load. The length of the hydraulic clamping cylinder(s) may in some applications extend generally forwardly from a supporting lift truck, and in other applications extend generally laterally from a supporting lift truck.

A load-handling clamp mountable on a lift truck has one or more hydraulic clamping cylinders of the type having two or more sequentially extensible stages capable of applying either load-weight-responsive variable hydraulic load-clamping force or, alternatively, load-size-responsive variable hydraulic load-clamping force, without risking the clamp's dropping of a clamped load. The length of the hydraulic clamping cylinder(s) may in some applications extend generally forwardly from a supporting lift truck, and in other applications extend generally laterally from a supporting lift truck.

A current controller includes a current control circuit and a current detection circuit, which detects a current flowing through a solenoid of an electromagnetic proportional relief valve. The current control circuit sets a current command to a sum of a value obtained by multiplying a feedforward gain by a target current value, a value obtained by multiplying a proportional gain by a current deviation, and a value obtained by multiplying an integral gain by a current deviation integral value. The current control circuit then controls the current flowing through the solenoid in accordance with the current command. When the current detected by the current detection circuit is less than or equal to the predetermined value, the current control circuit resets the current deviation and the current deviation integral value and sets the current command based on the reset values.

The present disclosure relates to a hydraulic circuit for a forklift, and more particularly, to a hydraulic circuit for a forklift which is capable of preventing an engine from being stopped due to surge pressure that instantaneously occurs when a lift cylinder reaches an end stroke and thus cannot be operated any further when the lift cylinder is extended. According to the hydraulic circuit for a forklift according to the exemplary embodiment of the present disclosure, which is configured as described above, the accumulator is provided on the hydraulic line through which the working fluid is provided to the lift cylinder, and as a result, the accumulator may quickly absorb surge pressure when the surge pressure is produced in the lift cylinder or the hydraulic line.

The present disclosure relates to a hydraulic circuit for a forklift, and more particularly, to a hydraulic circuit for a forklift which is capable of preventing an engine from being stopped due to surge pressure that instantaneously occurs when a lift cylinder reaches an end stroke and thus cannot be operated any further when the lift cylinder is extended. According to the hydraulic circuit for a forklift according to the exemplary embodiment of the present disclosure, which is configured as described above, the accumulator is provided on the hydraulic line through which the working fluid is provided to the lift cylinder, and as a result, the accumulator may quickly absorb surge pressure when the surge pressure is produced in the lift cylinder or the hydraulic line.

A robotic under surface loader includes a mobility platform, a parallel manipulator, and a cradle. The mobility platform enables the robotic under surface loader to be moved into place beneath a downwardly facing surface to which a payload is to be attached. The parallel manipulator, which is carried by the mobility platform, carries the cradle, which may in turn carry a payload. The parallel manipulator may position the cradle in six degrees-of-freedom and, thus, precisely position a payload carried by the cradle in a location and an orientation that will facilitate its interaction with (e.g., attachment to, etc.) the downwardly facing surface. Methods for attaching objects, including large, heaving objects, to downwardly facing surfaces are also disclosed.