Backstop position changing device for crane

A backstop posture changing device for crane, the crane including a crane body, a derricking body having a derricking body base end portion rotatably supported by the crane body in a derricking direction and a derricking body distal end portion on a side opposite to the derricking body base end portion, a backstop having a backstop base end portion supported so as to be rotatable around a horizontal reference rotation center axis at a portion of the derricking body between the derricking body distal end portion and the derricking body base end portion and a backstop distal end portion disposed on a side opposite to the backstop base end portion,

• the backstop posture changing device being configured to be attached to the derricking body and to change the posture of the backstop between a support posture and a storage posture by turning the backstop with the backstop base end portion as a fulcrum in a falling state of the derricking body that is a state where the derricking body is fallen with respect to the crane body, and, in the support posture, the backstop extending obliquely upward from the derricking body in such a manner that the backstop distal end portion of the backstop contacts with the crane body in accordance with the rising of the derricking body from the falling state, thereby the backstop restricts the falling of the derricking body backward, and, in the storage posture, the backstop distal end portion of the backstop being disposed closer to the derricking body than the backstop distal end portion in the support posture,
• the backstop posture changing device comprising:
• a first support member having a first base end portion connected to a portion of the backstop between the backstop distal end portion and the backstop base end portion so as to be rotatable around a first rotation center axis parallel to the reference rotation center axis, a first rotation end portion opposite to the first base end portion, and a pushed-up portion disposed between the first base end portion and the first rotation end portion;
• a second support member having a second base end portion connected to a portion of the derricking body between the derricking body base end portion and the backstop base end portion so as to be rotatable around a second rotation center axis parallel to the reference rotation center axis, and a second rotation end portion disposed on the opposite side of the second base end portion and connected to the first rotation end portion of the first support member so as to be relatively rotatable around an intermediate rotation center axis parallel to the reference rotation center axis, the second support member being arranged such that a first straight line connecting the first rotation center axis and the intermediate rotation center axis and a second straight line connecting the second rotation center axis and the intermediate rotation center axis form a first angle, thereby the second support member maintain the backstop in the support posture together with the first support member, and the second support member being arranged such that the first straight line and the second straight line form a second angle of an acute angle smaller than the first angle, thereby the second support member maintain the backstop in the storage posture together with the first support member;
• a push-up mechanism disposed so as to be interposed between the first support member and the second support member and including a cylindrical cylinder body having a base end portion supported by the second support member so as to be rotatable around a first cylinder rotation center axis parallel to the reference rotation center axis, and a cylinder rod inserted into the cylinder body so as to extendable and contractable with respect to the cylinder body on a side opposite to the base end portion, and a push-up member disposed at a distal end portion of the cylinder rod and capable of pushing up the pushed-up portion of the first support member to rotate the first support member relative to the second support member around the intermediate rotation center axis in accordance with the extending of the cylinder rod with respect to the cylinder body from a state where the first straight line and the second straight line form the second angle, thereby the first straight line and the second straight line forming the first angle;
• and
• a connection member detachably attached to at least one of the first support member and the second support member and capable of connecting the first support member and the second support member to each other so as to hold a state in which the first straight line and the second straight line form the first angle and the backstop is in the support posture.