Warner Electric Wheel-Brakes (Std) - Manual (Page 18)

18 Warner Electric • 800-825-9050 819-0514
During normal operation, the face of the armature and
magnet will become scored or grooved to some extent
(Figure 3-12). This condition is not detrimental and
does not show excessive wear or defective parts. In
the case of some magnets, termed “air gap” and
distinguished by an expansion groove in the magnet
facing, a ridge will appear on the armature opposite
this groove after considerable wear. It is recommended
that the ridge be partially ground off, so that at
maximum wear, it cannot cut through the magnet
facing and short out the magnet coil.
Figure 3-12
Typical Wear Patterns
Often times, when there is a complaint of weak brakes
and all other things appear normal, a glazed magnet
facing is at fault or a condition exists whereby the
magnet facing prevents the magnet poles from coming
into direct contact with the armature. This condition
may be remedied by placing the magnet in a lathe
(Figure 3-13) and undercutting the magnet facing
(Do Not machine the magnet poles) with a carbon
tipped tool or by using a small piece of sandpaper
(Do Not use emery cloth) on the finger tips or on a
small block of wood. Whenever possible, use only
sandpaper; undercutting the magnet facing in a lathe
reduces magnet wear life.
Replacement of Magnets and Armatures
Note: All single wire magnets are replaceable
with 2 wire magnets by grounding one wire
to the brake.
Table IV is a guide to determine when magnet and
armature should no longer be refaced. As indicated
magnets and armatures may be used even when
dimensions “A” and “B” are below the minimum;
but they should never be refaced when below this
minimum. If a magnet needs to be replaced, a new or
refaced armature must be used. However, an armature
may be replaced without replacing the magnet. In this
case, merely make certain the magnet facing is below
the magnet poles to insure proper pole contact initially.
Figure 3-13
Undercutting the Magnet Facing
New
Slightly Scored
(Normal)
Badly Scored
(Needs Replacement)