Patent ID: 6199707
Filing Date: 2001-03-13
Classification: B66C,B66F,Y10S

Abstract:
A telescopic boom comprising a first boom, a second boom inserted into said first boom so as to be able to extend and retract therein, and a third boom inserted into said second boom so as to be able to extend and retract therein, which are assembled together in a telescopic fashion, said telescopic boom further comprising:a telescopic cylinder, adapted to plunge into and out of said third boom, having a cylinder rod with a distal end portion fixedly attached to an inner proximal end portion of said first boom and a cylinder body fixedly attached to an inner proximal end portion of said second boom;a retraction sheave disposed aside of said telescopic cylinder nearer a proximal end portion thereof;an extension sheave disposed aside of said telescopic cylinder nearer a distal end portion thereof;a hollow rod member, disposed on an upper or lower side of said telescopic cylinder, having one end fixedly attached to a proximal end portion of said first boom and the other end extending between said retraction sheave and said extension sheave;a retraction wire, wound about said retraction sheave, having one end fixedly attached to a distal end portion of said rod member and the other end fixedly attached to a proximal end portion of said third boom;an extension wire, wound about said extension sheave, having one end fixedly attached to the distal end portion of said rod member and the other end fixedly attached to the proximal end portion of said third boom;flexible, tubular, hydraulic/electric feed protecting means having one end fixedly attached to the distal end portion of said rod member in communication therewith, extending toward said distal end portion, being reversed in the vicinity of an end portion of said cylinder body to provide a rolling bite, and extending toward the proximal end portion of said telescopic boom at a position opposing said rod member across said cylinder body, so as to connect with the proximal end portion of said third boom; andhydraulic/electric feed means extending from the proximal end side of said first boom through said hollow rod member and said flexible, tubular hydraulic/electric feed protecting means communicating therewith.