Abstract: A travel sensor (10) is proposed which has a insertion body (11) consisting of non-ferromagnetic material with good conductive properties. The insertion body (11) is submerged into a measuring coil (15) through which alternating current flows. In addition, the travel sensor is enveloped by a shielding sleeve (16) consisting of ferromagnetic material. Due to the alternating effect between the magnetic field of the coil (15), through which an alternating current flows, and the two materials, at designated frequencies of the alternating current and the respective volume of the insertion body (11) or the shielding sleeve (16), it is possible to compensate the effects of the temperature in such a way that at varying temperatures the measuring curves of the travel sensor (10) extend nearly parallel across the entire measuring range.

Abstract: An apparatus for time dependent control of a regeneration time of an air-dryer. The control apparatus has a shutoff valve, which is disposed in a line between a tank that furnishes regeneration air and an air dryer that can be regenerated by the countercurrent method. For the regeneration of the air dryer, the shutoff valve is switched into an open position by a control pressure and is returned to its closing position by spring force counter to a pneumatic delay device which concludes the regeneration. In the pneumatic delay device, air is displaced through a throttle restriction in the form of a permeable membrane, for instance of porous polytetrafluoroethylene. The apparatus for time-dependent control of the regeneration time of an air dryer is intended in particular for compressed air systems of motor vehicles.