The back portion of the pole pieces of part (Ref, 28) are machined for approximately one-half their surface on a 4-3/8" radius conforming with radius of swinging armature (net. 63).  The re-maining one-half portion of the pole surfaces are machined on a straight angle to provide additional clearance on the initial pull over of the armature.  The initial setting of the magnets should be made so that the radius of the back portion of the pole pieces is parallel to the radius of the armature, although in final adjustment it may be necessary to tilt the mag-nets slightly toward the armature which will decrease the front clearance and increase the pull over from the normal vertical position of the armature.

Generally the front edge of each pole piece is located from 1/4" to 5/16" from the edge of the armature when in its normal vertical position although the magnets should be actually set by determining the position that will provide the greatest magnetic pull at minimum voltage upon breaking of the movable finger contact. This occurs at 11 degrees from the vertical position in either direction.  When the magnets are fi-nally adjusted the mechanism must start and move a minimum of 11 degrees in either direction when a maximum of 4.8 volts is applied to the coils. This test is made with a voltmeter connected across the coils and a variable resistor in series with the coils.  Adjust voltage while banner is held stationary, open the circuit and re-close when the banner is at rest.

The minimum air gap between the armature and pole faces is to be not less than .010" after the finish has been applied and when the coils are energized at 8 volts.

After the magnet adjustments are complete they are to be locked in position by pouring molten lead in the space where mounted on the end castings.