Patent attributes
This invention disclosed a speed limit device for door, which comprises: an input shaft with one end driven by a door motor, and having the first gear and the second gear configured at the other end simultaneously driving a hollow shaft and a third shaft, and the center of the hollow shaft accommodates and fixes one end of a reel, and the third shaft is connected with an extension shaft; a brake device, which includes an active gear fixed with the extension shaft; a passive gear is pivoted on a hub, and the hub is fixed with the reel and rotating with the hollow shaft; an inert wheel located between the active gear and the passive gear to adjust the passive gear to have the same rotation speed with the hollow shaft; a clutch mechanism, which could restrain the synchronous operation between the passive gear and the hub without any positional difference, and when the rotation speed of the reel has the abnormal change, the clutch mechanism generates the positional difference condition necessary to lock the hub to a fixed object to prevent the rolling door from falling.
