Raisable-lowerable member

摘要

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.

主权项

1. A raisable-lowerable member designed to be provided in a construction machine, comprising a boom, and a jib attachable to a tip end of the boom,
wherein the jib comprises:
a frame;a jib foot provided at one end of the frame constituting a base end of the jib, and configured to be supported by the boom in a rotatable manner with respect to the boom when the jib is set in a protruding posture where it protrudes from the tip end of the boom;a supportable portion provided in the frame, and configured to be supported by the boom in a rotatable manner with respect to the boom when the jib is set in an enfolded posture where it extends from the tip end of the boom toward a base end of the boom along a belly surface of the boom;a first link coupled to the frame in a rotatable manner about a first axis coincident with a rotational axis of the jib foot;a second link coupled to the frame in a rotatable manner about a second axis coincident with a rotational axis of the supportable portion; anda position adjusting and holding unit for adjusting a relative position of the second link with respect to the frame, and wherein the first link has a first joint portion which is provided at a position away from the rotational axis of the first link and is attachable and detachable with respect to the boom, and the second link has a second joint portion which is provided at a position away from the rotational axis of the second link, and is attachable and detachable with respect to the boom, and wherein the boom comprises:
a first supporting portion provided at the tip end of the boom, and configured to rotatably support the jib foot when the jib is set in the protruding posture;a second supporting portion provided at a position away from the first supporting portion and toward the belly surface of the boom, and configured to rotatably support the supportable portion when the jib is set in the enfolded posture; anda third supporting portion configured to detachably support the second joint portion in such a manner as to allow the second joint portion to be rotated about an axis coincident with the rotational axis of the jib foot being supported by the first supporting portion, and wherein the position adjusting and holding unit is configured to couple, to the frame, a specific site of the second link away from the second axis, 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.