Electromagnetic actuator

Claim 1

IN AN ELECTROMAGNETIC OPERATOR, IN COMBINATION: A CORE AND AN ARMATURE RELATIVELY MOVABLE UPON A COMMON AXIS, SAID CORE INCLUDING AN ARBOR AND A COIL HOUSING COAXIALLY SURROUNDING SAID ARBOR, SAID ARBOR AND HOUSING BEING SECURED TOGETHER AT THEIR ONE ENDS, SAID ARBOR HAVING AT ITS OTHER END A COUNTERBORE AND SAID HOUSING HAVING AT ITS OTHER END AN ANNULAR END PLATE SPACED AXIALLY FROM SAID OTHER END OF THE ARBOR AND HAVING AN INTERNAL SURFACE DEFINING A CENTRAL APERTURE THEREIN; SAID ARMATURE INCLUDING A HEAD PORTION DISPOSED WITHIN SAID END PLATE APERTURE AND A NECK PORTION IN OPPOSED RELATION TO SAID ARBOR COUNTERBORE, SAID HEAD PORTION DEFINING A SUBSTANTIALLY RADIAL SHOULDER ADJOINING SAID NECK PORTION AND IN OPPOSED, MAGNETICALLY ATTRACTING RELATION TO SAID OTHER END OF SAID ARBOR TO PROVIDE AN AXIAL GAP IN WHICH THE MAJOR FLOW OF MAGNETIC FLUX EFFECTIVE FOR DEVELOPING AXIAL PULL BETWEEN THE ARMATURE AND CORE IS DEVELOPED; SAID NECK BEING ARRANGED TO ENTER SAID COUNTERBORE AS RELATIVE MOVEMENT BETWEEN THE ARMATURE AND CORE OCCURS, SO AS TO DEVELOP A FLUX-SHUNTING RADIAL GAP BETWEEN SAID NECK AND COUNTERBORE IN WHICH MAGNETIC FLUX BETWEEN SAID ARMATURE AND CORE IS SHUNTED TO AN EXTENT WHICH IS MINIMAL WHEN THE ARMATURE AND CORE ARE AT MAXIMUM SPACING AND WHICH PROGRESSIVELY INCREASES AS SAID ARMATURE AND CORE APPROACH ONE ANOTHER, WITH AN INCREASE SUCH AS TO PROVIDE A SUBSTANTIALLY CONSTANT PULL BETWEEN THE ARMATURE AND CORE THROUGHOUT THE RANGE OF RELATIVE MOVEMENT.