Abstract: A brake of this type has a brake shaft and a brake wing secured to the shaft so that the wing is rotatable with the shaft in a brake housing filled with a brake medium. A cam ring located in the brake housing has a control curve or surface which cooperates with a cut-out in the brake wing so that the size of a gap formed between the cam ring surface and the brake wing depends on the angular position of the wing relative to the cam ring whereby the dampening action of the brake medium on the movement of the brake wing varies with said angular position of the brake wing relative to the normally stationary cam ring.