DISLODGEMENT-PREVENTING DETECTION DEVICE FOR EXTENDABLE AND RETRACTABLE BEAM FOR MOBILE CRANE, AND MOBILE CRANE

摘要

The object to be detected by a dislodgement-preventing detection device for an extendable and retractable beam is an extendable and retractable beam that comprises a plurality of telescopically arranged cylindrical members. A dislodgement-preventing detection device for an extendable and retractable beam is provided with a detector and a change mechanism. The detector has at least a part thereof disposed between first and second cylindrical members at a position before the position where the first cylindrical member dislodges from the second cylindrical member in the direction in which the extendable and retractable beam extends and retracts, the first and second cylindrical members being located adjacent to each other in an inside-outside relationship in a cross-sectional direction of the extendable and retractable beam. The change mechanism allows the position of the detector relative to the first and second cylindrical members in the cross-sectional direction of the extendable and retractable beam to change following a change in the gap between the first and second cylindrical members in the cross-sectional direction of the extendable and retractable beam.