| 摘要 |
<p>1497270 Crane safety devices E KIRSTEN 31 Dec 1974 [4 Jan 1974] 56144/74 Heading B8B Apparatus for preventing the tilting of a telescopic jib crane wherein an hydraulic cylinder 7 is provided for luffing the jib 5 comprises a circuit, Fig. 3, including a set of switches 16 to 20 which sequentially open or close through pivotal movement of the cylinder 7 as it raises or lowers the jib 5, a set of pressure monitor switches 10 to 15 which sequentially open or close as the pressure in the cylinder 7 increases or decreases, a telescope switch 23 which is open when the jib 5 is telescopically extended and a relay 24 which is energized so long as the permissible tilting moment for the particular configuration in use, Fig. 2 (not shown), is not exceeded. Above the limit the relay 24 acts to terminate crane operations which would increase the tilting moment.</p> |
