Abstract: A door release mechanism includes a drop wheel coupled to a holding brake sprocket; a brake drive sprocket fixed to a drop wheel coupled with a governor; and a drop arm having a tooth to mesh with the drop wheel. The drop arm has an engaged position and a disengaged position. In the engaged position, the drop arm prevents rotation of the brake drive sprocket; in the disengaged position, the drop arm allows rotation of the brake drive sprocket. The door release mechanism includes a second brake having a brake sprocket rotationally coupled to the brake drive sprocket. The second brake is configured to provide resistance to rotation of the brake sprocket in response to rotation of the brake sprocket exceeding a predetermined braking speed.

Abstract: A door mechanism includes a bracket and a door shaft, rotationally mounted to the bracket, to operate a door. The door mechanism includes a gear assembly having a ring gear, set of planetary gears, sun gear, and drive sprocket. The ring gear fixed to the door shaft. The door mechanism includes a holding brake to counter the closing bias of the door. The door release has an engaged position in which rotation of the door shaft in the second direction is impeded by a first brake; and a disengaged position in which rotation of the door shaft in the second direction is unimpeded by the first brake. The door mechanism includes a link and a second brake. The link is configured to melt in response to a predetermined temperature. The second brake is configured to provide resistance in response to component rotation exceeding a predetermined speed.

Abstract: A gearbox assembly includes a housing which contains a differential gear set and a two-speed reduction gear set. A spider drives differential pinion gears nested between outer pinion gears. A first and a second clutch that can be engaged “on the fly” achieve the two-speed functionally of the gearbox assembly. Another gearbox assembly includes an on-demand locking differential with a differential clutch located between differential axle side gears to selectively lock the differential axle side gears together and thereby lock the axle shafts.