GB980132A - Improvements in safe load indicating devices for cranes - Google Patents

Abstract

980,132. Safe load indicators for cranes with telescopic jibs. R. L. AITKEN. Feb. 6, 1963 [Feb. 9, 1962], No. 5177/62. Heading B8B. A device for use with a safeload indicator as described in Specifications 723,070 and 978,822 converts the latter for use with cranes having telescopically extensible jibs. Changes in jib angle are communicated to a lever 9, Fig. 1, by links 1, 1a, a cam 2 and a lever 5 carrying a camfollower 7. Changes in jib length are transferred to the lever 9 through links 10, 10a, a cam 11, a lever 13 and a crosshead 16 which slides in a slot 18. Movements of the lever 9 are applied to the jib angle compensating link of a safe load indicator of the type referred to above by a cable 22. In a second embodiment, Fig. 2, a bellcrank 50, 59 is pivoted about a pin 51 by changes of jib angle through links 31, 31a, cam 32, levers 35, 53 and a crosshead 52. Telescopic movements of the jib are transferred to the bell-crank 50, 59 by links 41, 41a, a cam 42, levers 44, 47 and a cable 49 which slides the crosshead 52 up and down the limb 50 of the bell-crank. The movements of the bell-crank are fed to the jib angle compensating link of a safe load indicator by a link 60. Fig. 4 show a device which is used in conjunction with one of the devices described with reference to Figs. 1, 2. It is intended for use with a crane which is luffed by an hydraulic cam and produces a correction which is proportional to the ram moment arm about the jib foot pin of the crane. The hydraulic pressure in the ram is applied to a lever 79 through a spring-loaded piston 73 and a lever 76, whilst change of ram angle, which is proportional to change of jib angle, is fed to the lever 79 through a rod 80, cam 81 and bellcrank 83. The movements of this lever are transmitted through a rod 90 to a device as described above.