HOUSING DEVICE OF EXTENSION BOOM IN EXPANSION BOOM

摘要

PURPOSE:To further expand the length of an expansion boom as necessary up to length more than the length while housing an extension boom when the extension boom is not used, in the expansion boom that the maximum stretch length is beforehand set. CONSTITUTION:When stretching the length of an expansion boom up to length more than the maximum stretch length of the expansion boom 1 by using an extension boom 4, one side of the base ends of the extension boom 4 is connected to one side of the noses of an inside boom 3 in a revolution-free shape by means of a pivotal support pin 5, and a pivotal support pin 6 is inserted, thus fixing both booms under a stretching condition. When intending to house the extension boom 4 to a housing location under a condition that the boom is not used, said pivotal support pin 6 is pulled out, and the boom 4 is turned up to a location along a boom 2 at the base end side centering around the pivotal support pin 5 and folded up. A deep groove block 7 is connected to a regulating rail 8 of the boom 2 with the contraction operation of the expansion boom 1, and the boom 4 is fixed under a housing condition.