Measuring spindle 1, bearing against workpiece a being inspected,
is pushed to the left by spring 2 and, at the m in im um lim it
of size of workpiece a, closes contacts 3 and 4. When the workpiece
is of larger size, spindle 1 moves to the right, opening
contacts 3 and 4 and, at the m a x im um lim it of size, contacts 5
and 6 are closed. The contacts close sig na lling circuits that
enable over- or undersize workpieces to be rejected.