Abstract: In order to ensure an optimal position of a magnet (3) in relation to a Hall IC (2) or, respectively, its Hall effect elements (4, 5), the magnet (3) and the Hall IC (2) are displaceable in relation to one another and, namely, in the direction of the lateral distance of the two Hall effect elements (4, 5). It is preferred that the Hall IC (2) is retained stationarily in the rotational speed sensor, and the magnet (3) is retained so as to be displaceable and lockable in position, in particular in a base member (10) of the sensor housing.

Abstract: The present invention relates to a transducer with a piezoelectric crystal for parking aids in automotive vehicles. Such transducers must be sealed against steam jets. This object is achieved by the present invention by means of a plug including projections forming an evacuatable chamber in conjunction with the inner wall of a housing bowl. Developments of the present invention relate to the protection and sealing of the diaphragm retainer, which is part of the transducer, against moisture and mechanical displacement due to vibrations and other environmental influences.