Dish-washers of catering type are often carelessly handled. A condition for a long life of the locking device in a hood dish-washing machine with automatic opening of the hood (13) is that the hood can also be opened manually. A locking device (20) in which the curve portion (31) can be removed from the curve follower included therein both electromechanically and mechanically is according to the invention a solution to the locking problem in such machines.