Abstract: Disclosed is control apparatus for a machine such as crane which includes a remote control assembly fluid-coupled to the machine by a substantially electrically non-conducting tube assembly. The machine can be operated remotely from the remote control assembly or from an electrical control assembly disposed at the machine. Apparatus is provided for automatically shutting down all or selected machine functions in response to a blockage in one or more of the fluid lines extending between the remote control apparatus and the machine. In a preferred embodiment, the remote control assembly includes pneumatic switches coupled by the fluid lines to electric pressure switches disposed at the machine. The pressure switches are in turn coupled to electro-mechanical devices for controlling the machine functions.