GB220261A - Improvements in or relating to ship's derricks and like cranes - Google Patents

Abstract

220,261. Hansen, L. E. May 14, 1923. Derricks.-Relates to derricks of the kind in which a swivelling pulley is mounted in a housing A, Figs. 1 and 4, at the top of the crane mast to lead the load rope 6 through the hollow mast to the winch. The swivelling housing A is outside the mast and is provided with a flange 47 which is retained in a groove in a cylindrical member 36 secured on or within the top of the mast. The lower end of the derrick 7 is mounted on a pin 9, Fig. 6, in a ring 10 provided with ball or roller bearings which take both vertical and horizontal pressures. Two derricks may be mounted on two crane masts 3 which are side by side and are braced together by a transverse member at the top. The winches may be enclosed in deck-houses 21 behind the masts, and the controlling gear may be on the roofs of these houses. The hoisting rope 6 may be led from the lower part of the crane mast to electrically-operated winches amidships through a casing below the deck, and an electric cable for the controls may pass through the same casing to a suitable operating station. The luffing line 19 passes through pulley blocks 16, 17, 18. The block 16 is mounted on a strap 14 pivoted on the pin 9, and the block 17 is supported from the swivelling member A. The pin 9 is formed at one end as a cleat for securing the luffing line. The arrangement facilitates luffing and slueing, and provides a free space around the crane masts for the loading operations. To enable a derrick to swing through a complete circle, stays for the mast are dispensed with, or in applying the invention to existing vessels with hollow crane masts the ring 10 is fixed above the stays. In one form of construction, the swivelling housing A contains two sheaves 40, 41, Fig. 4, the sheave 41 taking part of the pressure when the derrickis in its lowest positions.