GB502189A - Improvement in derrick cranes - Google Patents

Abstract

502,189. Controlling the luffing-gear of cranes; locking levers; clutches. DAW, E., and DEWES, R. H. Sept. 29, 1937, No. 26320. [Class 78 (v)] [Also in Group XXIV] The clutch lever, which connects and disconnects the luffing-mechanism of a jib crane to the power gear, is fitted with spring-actuated mechanism which passes its dead centre as the lever progresses from the " off to the " on " position and vice versa, thus acting positively to retain the lever in both of these positions. Figs. 1 and 3 show the lever 2 pivoted at 3 and actuating the claw clutch member 4 to drive the luffing- drum 5. In moving the lever to the " on " position, the cranked portion moves from right to left in the slot 6 in the fixed plate 1 ; the rod 7 sliding through the bearing 8 and compressing the spring until the dead centre is passed and then rising again as the spring re-expands. When the luffing motor is reversed, the drum 5 is held by the self-sustaining pawl 17 and the teeth force the members 4, 5 apart sufficiently for the spring to pass the dead centre. The spring then completes the movement and forces the lever into the recess 15 where it is secure until again positively operated. Various methods of mounting the rod 7 are described. As shown, it is connected to the lever by a ball-joint 10 with or without play, and has rolling contact at 14 with the plate 1, with or without a restraining trackway on the surface of the plate. The bracket 8 is mounted on ball bearings 12 and its shank 11 may have some play in the bearing so that it can tilt relatively thereto. In addition, the bracket may slide bodily in a direction perpendicular to the plate by compressing the spring 13.