Abstract: A piston sealed by a rolling membrane is arranged in a cylindrical housing comprising two components and this piston translates against the force of a return spring. A vibrating armature pump driven via two wires by a variable alternating voltage serves for operating the positioning drive. The vibrating armature pump draws hydraulic fluid from a reservoir chamber through an inlet opening and transports the hydraulic fluid through a return valve and through a first orifice into a pressure chamber. The piston is displaced downwardly conjointly with a piston rod. The pressure generated by the vibrating armature pump is dependent upon the applied voltage. A state of equilibrium between this pressure and the counterpressure of the spring arises such that the positioning drive is suitable for continuous control or regulation operations.

Abstract: A thermostatic expansible work element comprising a housing within which there is enclosed an expansible body. In the expansible body there extends the one pointed end of a work member in the form of a work pin or piston, the other end of which extends through an opening out of the housing. Between the opening and the end face of the expansible body which confronts such opening there is arranged a ring-shaped or annular disk which surrounds with a sliding fit the work pin or piston. The ring-shaped disk covers an annular space or gap between the opening and the outer diameter of the work pin or piston, so that the latter, during its displacement or stroke, also can be deflected out of its original axial direction without binding in the opening. The thermostatic expansible work element also can be externally heated so as to serve as a servo for remote actuation of an element, for instance valves.

Abstract: A hygrometer or hygrostat containing a hygroscopic body formed of wood.

Abstract: A thermostatic expansible material-working element with a housing filled with the material and a pin-shaped work piston which is pointed at one end. The work piston with its pointed end extends through an opening in the housing into the internal compartment thereof and upon thermal expansion of the expansible material such piston is displaced out of the housing. According to the invention the expansible material is a molded body predominantly formed of polytetrafluoroethylene, polytrifluoroethylene or polytetrafluoroethyleneperfluoropropylene.