DEVICE FOR EXTENDING/CONTRACTING BOOM BY CRANE ELECTRIC BOOM SELECT SWITCH

摘要

PURPOSE: A device for extending/contracting a boom by a crane electric boom-selecting switch is provided to sequentially extend the boom and to prevent an accident by generating warning sound. CONSTITUTION: A device for extending/contracting boom by using a crane electric boom selecting switch comprises a central process unit(4) detecting extension length of a crane boom through small and large cable reels(2,3); a boom selecting switch(7) deciding boom extending method; a solenoid valve reviving or isolating power according to selection of the boom selecting switch; a relay mounted on the central process unit; and a stop solenoid valve. The central process unit supplies power into the solenoid valve by extending the boom while selecting automatic stage through the boom-selecting switch. The central process unit isolates the power of the solenoid valve while selecting a manual stage through the boom-selecting switch. Thereby, the device for extending/contracting the boom by using the crane electric boom selecting switch prevents an accident by sequentially extend the boom.