Alarm device for underslung vehicle

The utility model relates to an alarming device for grab bucket hoister, which comprises a contact bar, a travel switch, an alarm, and battery, wherein the travel switch is connected with the alarm and battery in series to form an alarming circuit; the contact bar is arranged at the root of the large arm of the grab bucket hoister; and the travel switch is fixed at the place of the large arm bracket that is corresponding to the contact bar. When the large arm turns over to predetermined position, the contact bar contacts with the roller wheel of the travel switch, so that the alarming circuit is switched on and the alarm gives an alarm. When the large arm is recovered to the initial position, the alarming circuit is cut off, and the alarm stops alarming. The alarming device can effectively prevent the occurrence of abnormal damage of the large arm and bunker due to misoperation, and remarkably improves the stability and safety of the operation.