1911 seems to be for holding an animal in position, but not for pre-
takeoff of some sort. The 'entrance' (?) has a restraining chain &
strong catch/latch, the bracings are iron plates, the posts have big
eye bolts, and the board above the entrance may not be suitable for a
take-off of, say, a ridden/bucking horse. My best guess would be a
holder for castrating an adult bull or horse.