Abstract: A housing (11) which is intended for mounting on a process control valve (5) contains electric circuits (3) and means (4) controlled by these circuits for converting electric control signals into operating signals which operate the valve via a cylinder. The electric control signals are supplied via a serializing terminal (7) from the computer (1) of a process control system which includes a plurality of process control valves (5). The housing has a single interconnection (14) with a cable (8) common to several process control valves for transmitting the control signals and for supplying the electric circuits with power. The housing moreover has a single connecting socket (13) to permit coupling the housing to a pressure air line common to a plurality of valves (5).

Abstract: A rotatable shaft extends from the interior of a receptacle through a wall thereof forming a closed chamber surrounding the shaft; and a first sealing ring surrounding the shaft is operable to prevent flow into the chamber from the receptacle interior but to allow flow in the opposite direction, a second sealing ring surrounding the shaft to prevent flow from the chamber in the axial direction away from the receptacle interior. Valve means are operable selectively to connect the chamber to either a cleaning liquid supply source or a draining passage or to disconnect the chamber simultaneously from both said source and passage.

Abstract: A curd-cutting tool is rotatable about an axis within an immobile curdling container, driving means being provided for rotating this tool in one direction around said axis to cut the cheese curd; and means are operatively connected to the driving means for causing interruptions in the rotation of the tool in said one direction during the cutting operation.