GB1393191A - Jib crane with safety mechanism - Google Patents

Abstract

1393191 Jib tip safety devices FRIED KRUPP GmbH 27 April 1973 [29 April 1972] 20182/73 Heading B8B Safety mechanism for a jib tip 10 pivoted at 11 to a telescopic crane jib 2, 5, 6, 7 mounted for luffing about a pivot 3 by an hydraulic actuator 4 on a slewing platform 1 comprises two parts (I) (II), Fig. 2 (not shown). Part (I) is mounted on the jib tip 10 and includes a load measurer 16, a device 17 including a pendulum for measuring the inclination α of the jib tip 10 to the horizontal, a predetermined maximum load value generator (26) and a comparator (29) for comparing the actual load with the maximum allowable value. Part (II) is mounted at the bottom of the jib or on the crane superstructure and includes a source of constant current (20) and a decoder (42) connection between parts (I) and (II) being solely by a single conductor in the form of a jib-length indicating cable 8 secured to the end of the telescopic jib and wound on a tensioned drum 9 and the body (18) of the crane jib 2, 5, 6, 7 and jib tip 10, which act as forward and return conductors. The decoder (42) has an output (45) which acts to produce warning signals and shutting down of the crane mechanism in the event of an overload, upon sinking of the jib tip 10 to the horizontal, when the load strikes a stop on approaching its highest permissible position with respect to the jib tip 10 and in the event of a short circuit between the cable 8 and the body (18). A second output (46) of the decoder (42) shuts down the crane mechanism when the jib tip 10 attains its highest position or when the cable 8 breaks. Part (II) also includes an indicator (47) showing the instantaneous value of the angle α.