A fire-detecting device has first and second stressed brackets plugged together. The far ends of the first and second stressed brackets both have a towing hole. A disintegrable temperature-sensing device is between the first and second stressed brackets. First and second fixing pins are in the first and second brackets, respectively. The first fixing pin is located on one side of a free-moving piece and the second fixing pin is located on the other side thereof. A guide groove is in the first stressed bracket to correspond to the second fixing pin. A guide recess is in the second stressed bracket. A stressed shaft is in the second stressed bracket. An extension part having a stressed groove is in the first stressed bracket. When the disintegrable temperature-sensing device cracks off due to high temperature, the two stressed brackets will separate, leading to the fire dampers' shutting.

A fire-detecting device has first and second stressed brackets plugged together. The far ends of the first and second stressed brackets both have a towing hole. A disintegrable temperature-sensing device is between the first and second stressed brackets. First and second fixing pins are in the first and second brackets, respectively. The first fixing pin is located on one side of a free-moving piece and the second fixing pin is located on the other side thereof. A guide groove is in the first stressed bracket to correspond to the second fixing pin. A guide recess is in the second stressed bracket. A stressed shaft is in the second stressed bracket. An extension part having a stressed groove is in the first stressed bracket. When the disintegrable temperature-sensing device cracks off due to high temperature, the two stressed brackets will separate, leading to the fire dampers' shutting.