Abstract: A variable reluctance sensor is disclosed as adapted for sensing the rate of revolution of a toothed wheel of magnetic material. The sensor has at least two magnets disposed side by side. One of the magnet has a first pole (e.g. S pole) disposed opposite the toothed wheel, and the other magnet has a second pole (e.g. N pole) disposed opposite the toothed wheel. The second pole of the first mentioned magnet and the first pole of the second magnet are both held against a magnetic core around which a coil is wound. As the teeth of the magnetic wheel successively travel past the magnets, they create magnetic fluxes oriented in opposite directions, which counteract each other in the core. Consequently, the total magnetic flux in the magnetic member varies more greatly than heretofore depending upon whether each magnet is opposed to any one tooth, or to the space between any two neighboring teeth, of the magnetic wheel.

Abstract: An electromagnetic actuator including a stator and an armature having opposed flat faces which are movable relative to each other, grooves formed in the flat face of the stator facing the flat face of the armature, with endless coils received in the grooves, and bore hole formed in the stator for fluid communication between the grooves, for allowing resin to be poured in the bore hole and thus fill the grooves with the endless coils therein.