Measuring spindle 1, contacting workpiece a being inspected,
slides in a hole of the pickup housing. Overcoming the resistance
of spring 4, spindle 1 moves armature 3 an am ount depending
upon the size of workpiece a. This changes the clearances between
armature 3 and two electromagnets 2, thereby changing
their impedance. The impedance of the coils of electromagnets 2
is used as a measure of the workpiece size.
$4364$SmE,M$