Traveling crane with telescoping boom

Abstract

A traveling crane including a telescoping boom whose individual telescopically extending boom members are able to be extended and retracted after the disengagement of locking bolt connections using one single stage hydraulic piston and cylinder unit. The boom members are bolted in the respective extended or retracted positions by locking bolts spring-loaded toward the locked setting thereof. The piston rod of the piston and cylinder unit is pivotally attached to the boom joint member terminating the inner end of the outer boom member. An entraining device, which is able to be coupled with a receiving member on the telescopically extending boom members, is arranged in a part of the end of the cylinder, from which the piston rod comes out of the cylinder. Each of the telescoping boom members is provided at its inner end with at least one locking bolt, which is urged by a spring in a radial extension direction to lock in a hole provided at the inner end or adjacent to the outer end of the boom member encompassing such boom member. At an outer end thereof the locking bolt possesses a coupling member, which in the locking position of the locking bolt is coupled with the piston or piston rod of a hydraulic piston and cylinder unit arranged radially on the piston rod end of the cylinder. A drive is provided, which moves the cylinder accurately into the coupling position.