Abstract: A crane includes a jib posture retention device that retains a jib in a frontward tilt posture to a boom. The jib posture retention device includes a jib mast that holds a rope connection part at a tensioning position separate from a jib proximal end and a boom distal end backward thereof to render a jib-side support rope and a boom-side support rope linearly tensioned with the jib in the frontward tilt posture. The jib mast is shiftable to a tension form of holding the rope connection part at a tensioning position in an uprise posture and a looseness allowing form of locating the rope connection part at a looseness allowing position closer to the boom distal end than the tensioning position and closer to the jib proximal end than the tensioning position to allow the jib-side support rope and the boom-side support rope to be loosened.

Abstract: A damage estimation device includes: an operation parameter reception unit that acquires an operation parameter related to an operation of a work machine; a damage estimation model storage unit that stores a damage estimation model constructed by machine learning using training data with the operation parameter as an input value and a damage parameter related to damage in a predetermined portion of the work machine as an output value; and a damage parameter estimation unit that estimates the damage parameter by inputting the operation parameter acquired by the operation parameter reception unit to the damage estimation model stored in the damage estimation model storage unit.