SETT ATT RESA EN TELESKOPISK ANORDNING, SASOM EN TORNKRAN SAMT ANORDNING FOR UTFORANDE AV SETTET

摘要

A telescopic mast or tower, particularly the tower of a mobile tower crane, in which the sections are telescopically extendible by a hydraulic cylinder and have wedging means on adjacent sections which come into engagement when the adjacent tower sections are fully extended relative to each other. The wedging means both limit extension of the tower sections and hold these rigidly together when extended. The hydraulic cylinder is constantly maintained under pressure while the crane is operating to maintain the pressure between the wedges and to reduce or eliminate compressive stress in the tower.