Differential pressure switch and sensor

A differential pressure switch having a piston which is guided in a piston housing in a cylinder bore against the force of a return element, the piston head having a pressure P 1 applied to it, while a bore space around its tapered piston shaft has a pressure P 2 applied to it. A switching process is triggered by movement of the piston, the piston tip acting on a switching element and being sealed in relation to the cylinder bore by a rolling diaphragm which is movable within the range of axial movement of the piston.