Abstract: Provided is a crane which comprises a luffing jib including a lower jib and an upper jib coupled to the lower jib in such a manner as to be separable from the lower jib, the lower jib is attached to a head of a boom to have a laid-down posture at a position between the boom and a strut when the upper jib is separated from the lower jib, when the boom is lowered and laid down to allow the head of the boom to come into contact with a ground and when the strut is lowered and laid down to allow a distal end of the strut to come into contact with the ground, and the lower jib has a length which causes no interference with the strut when the lower jib has the laid-down posture at the position between the boom and the strut.

Abstract: Disclosed is a raisable-lowerable member which comprises a boom and a jib. The boom comprises a first supporting portion configured to rotatably support a jib foot when the jib is set in a protruding posture; and a second supporting portion configured to rotatably support a supportable portion of the jib when the jib is set in an enfolded posture. A position adjusting and holding unit of the jib is configured to couple, to the frame, a specific site of the second link in such a manner that a relative position of the second link with respect to the frame in a rotational direction of the second link is adjustably changed to allow the rotational axis of the second joint portion to become coincident with the rotational axis of the jib foot, and to hold the second link at the changed relative position.

Abstract: Disclosed is a raisable-lowerable member which comprises a boom and a jib. The boom comprises a first supporting portion configured to rotatably support a jib foot when the jib is set in a protruding posture; and a second supporting portion configured to rotatably support a supportable portion of the jib when the jib is set in an enfolded posture. A position adjusting and holding unit of the jib is configured to couple, to the frame, a specific site of the second link in such a manner that a relative position of the second link with respect to the frame in a rotational direction of the second link is adjustably changed to allow the rotational axis of the second joint portion to become coincident with the rotational axis of the jib foot, and to hold the second link at the changed relative position.

Abstract: Provided is a crane which comprises a luffing jib including a lower jib and an upper jib coupled to the lower jib in such a manner as to be separable from the lower jib, the lower jib is attached to a head of a boom to have a laid-down posture at a position between the boom and a strut when the upper jib is separated from the lower jib, when the boom is lowered and laid down to allow the head of the boom to come into contact with a ground and when the strut is lowered and laid down to allow a distal end of the strut to come into contact with the ground, and the lower jib has a length which causes no interference with the strut when the lower jib has the laid-down posture at the position between the boom and the strut.

Abstract: Provided is a mobile crane capable of adjusting a counterweight height with no use of a costly hydraulic cylinder. The mobile crane comprises a lower propelling body, a upper slewing body, a boom pivotably attached to the upper slewing body, a mast which is at the rear of the boom and adapted to be raised and lowered so as to raise and lower the boom, a counterweight which is at the rear of the upper slewing body and hung from the mast through a guy line, and a counterweight-lifting cylinder attached to the counterweight so as to be extended to vertically push up the counterweight with respect to a ground surface. The counterweight-lifting cylinder has a cylinder body, a piston partitioning an internal space of the cylinder body into an upper head-side cylinder chamber and a lower rod-side cylinder chamber, and a rod extending from the piston downwardly beyond an lower end of the cylinder body.

Abstract: In a lattice boom, a first reinforcing lattice member includes a first reinforcing pipe which has a portion extending in the same direction as a first main member of a base boom and which is separated outward from a first side surface of the base boom and a first mounting part which is provided on the first reinforcing pipe and which is mounted to the first main member so as to transfer a load acting on the first main member in an axial direction of the first main member to the first reinforcing pipe, and a second reinforcing lattice member includes a second reinforcing pipe which has a portion extending in the same direction as a second main member of the base boom and which is separated outward from a second side surface of the base boom and a second mounting part which is provided on the second reinforcing pipe and which is mounted to the second main member so as to transfer a load acting on the second main member in an axial direction of the second main member to the second reinforcing pipe.

Abstract: Provided is a mobile crane capable of adjusting a counterweight height with no use of a costly hydraulic cylinder. The mobile crane comprises a lower propelling body, a upper slewing body, a boom pivotably attached to the upper slewing body, a mast which is at the rear of the boom and adapted to be raised and lowered so as to raise and lower the boom, a counterweight which is at the rear of the upper slewing body and hung from the mast through a guy line, and a counterweight-lifting cylinder attached to the counterweight so as to be extended to vertically push up the counterweight with respect to a ground surface. The counterweight-lifting cylinder has a cylinder body, a piston partitioning an internal space of the cylinder body into an upper head-side cylinder chamber and a lower rod-side cylinder chamber, and a rod extending from the piston downwardly beyond an lower end of the cylinder body.

Abstract: A boom hoisting device comprising a mast having a pivotable front end portion connected to a front end portion of a boom through a guy line, a mast-side spreader provided at the front end portion of the mast, a frame-side spreader removably mounted to an upper rotating body and with a hoisting rope being stretched between and spread on both mast-side spreader and frame-side spreader, and a hoisting winch adapted to unwind and wind the hoisting rope to raise and lower the mast and the boom, the hoisting winch being mounted to the mast so that the mast and the hoisting winch are together removed from the upper rotating body by separation of a base end portion of the mast from the upper rotating body.

Abstract: A crane includes a boom and boom pivoting mast connected to a swivel body so as to be pivotable, a boom pivoting winch for pivoting the boom, and a main hoisting winch and auxiliary hoisting winch for hoisting up and hoisting down a hanging load. The main and auxiliary hoisting winches are mounted on the boom, while the boom pivoting winch is mounted on the boom pivoting mast.

Abstract: A crane includes a boom and boom pivoting mast connected to a swivel body so as to be pivotable, a boom pivoting winch for pivoting the boom, and a main hoisting winch and auxiliary hoisting winch for hoisting up and hoisting down a hanging load. The main and auxiliary hoisting winches are mounted on the boom, while the boom pivoting winch is mounted on the boom pivoting mast.

Abstract: A boom hoisting device comprising a mast having a pivotable front end portion connected to a front end portion of a boom through a guy line, a mast-side spreader provided at the front end portion of the mast, a frame-side spreader removably mounted to an upper rotating body and with a hoisting rope being stretched between and spread on both mast-side spreader and frame-side spreader, and a hoisting winch adapted to unwind and wind the hoisting rope to raise and lower the mast and the boom, the hoisting winch being mounted to the mast so that the mast and the hoisting winch are together removed from the upper rotating body by separation of a base end portion of the mast from the upper rotating body.