GB985543A - An improved tower crane and a method for erecting and dismantling such a crane - Google Patents

Abstract

985,543. Self-erecting tower-cranes. SOC. NOUVELLE D'EXPLOITATION DES ETABLISSEMENTS BOILOT-PETOLAT. Oct. 22, 1963 [Oct. 23, 1962; March 13, 1963], No. 41640/63. Heading B8B. To dismantle a tower-crane having a tower comprising sections P 1 , P 2 , Fig. 1, hinged at F a cable C is disconnected from a point B and attached to a point A. The jib V is now supported by a block and tackle M 1 , T, which extends between a winch S and a cable K attached to a strut P and a point E on the sector p 2 . If the tackle M 1 is slackened off the jib will move downwards until cable C supports the weight again, Fig. 3. The tension in the cable C and the consequent thrust in a strut P causes the tower to fold about its hinge and the jib to continue to descend after a pin F has been withdrawn and as long as the cable M 1 is paid out. Fig. 7 shows the completely folded position. In a second embodiment which allows erection with a smaller tension in the cable M 1 the section p 2 is not raised until the section p 1 has reached a certain angle of inclination. The end of each strut G. is attached to the section p 2 by a pin I, Fig. 8a, which slides in a guide J. Thus, no thrust is transmitted to p 2 to raise it until section p 1 is in the position shown in Fig. 10. Whilst the raising procedes a lever Z which is rotated by the block and tackle M 1 applies a lifting force to the section p 2 . By the time the tower is vertical two semi-circular locking members N 1 , N 2 respectively on the struts G and guides J have turned and nested within each other to prevent the pins I from running back in the guides.