GB1079375A - Overhead gantry crane with extensible bridge girder carrying legs - Google Patents

Abstract

1,079,375. Bridge cranes. V. POROLI. Feb. 18, 1965 [March 3, 1964], No. 7108/65. Heading B8B. An overhead gantry crane comprises a bridge 2, Fig. 1, supported on legs which are formed by a plurality of vertically superposed, releasably interconnected sections 1, 2a, lifting means being provided at each leg for the separation of the sections 1, 2a so that a further section 1a can be interposed therebetween. Each section 1 has wheels 4, Fig. 3 (not shown), for running on rails 5 and has releasably attached thereto a structural member 6 in which is mounted a threaded spindle 7, Fig. 4 (not shown), the associated section 2a having secured thereto a nut 8 which is engaged with the spindle 7. The latter is rotatable by a motor 17. The bridge 2 may extend directly above the legs, Fig. 1, or to one side thereof with the structures 6 disposed 90 degrees from their position shown in Fig. 1, Fig. 4 (not shown). In the latter case the bridge 2 may extend past the legs. On each section 2a there is provided a runway 18 on which is movably disposed a drivable carriage 20 carrying a hook 19. The drives of the spindle 7 and the carriage 20 may be synchronized. The operation to extend the legs consists in first using lifting means 21, carried by a movable trolley on the bridge 2 to place the sections 1a on the hooks 19. The connections between the sections 1 and 2a are then released and the bridge lifted by rotating the spindles 7 to raise the nuts 8. Next, the carriages 20 are moved to insert the section 1a carried on the hooks 19 and these are then rigidly connected to the sections 1 and 2a. Finally, the members 6 are released from their attachment to the sections 1, are moved upwardly by reverse rotation of the spindles 7 and are attached to the inserted sections 1a ready for any further extension of the legs.