Warner Electric Wheel-Brakes (Std) - Manual (Page 12)

12 Warner Electric • 800-825-9050 819-0514
Section lll Maintenance
During preventive maintenance periods or when
attempting to diagnose brake troubles, three simple
checking procedures should be followed. Merely by
checking the current available for braking, the approxi-
mate amount of brake lining wear, and whether or not
the wheel bearings are tight; most brake troubles can
be pin pointed and the condition of the electric brake
system determined.
Check Current Available
Be sure that the electrical circuit of the towing vehicle
is connected to the electrical circuit of the trailer
(Figure 3-1). It is good practice to check and clean the
socket and plug contacts periodically to insure a clean,
tight connection.
Figure 3-1
Towing Vehicle Electrical Connection
Remove either one of the brake circuit wires from a
controller terminal and connect a low reading DC
ammeter (15-25 amp. capacity) between the controller
terminal and the wire just removed (Figure 3-2). Make
certain load control is set at 100% (full on). Start
engine and idle fast enough to insure full battery
charge.
Figure 3-2
Connecting Ammeter to Controller and Brake Wire
Make a light, fast application of the controller
(Figure 3-3) and observe the direction of movement
of the ammeter needle. If needle moves in wrong
direction, reverse the ammeter leads. Current of the
wrong polarity in excessive amounts can damage the
ammeter. When ammeter is correctly connected in the
brake circuit, make a full application of the controller,
noting the total current in the circuit as shown by the
ammeter. Move the load control from 100% to 0 and
observe movement of ammeter needle. There should
be a gradual reduction of current. Return load control
to 100% and note current reading. If same as previous
reading, load control is operating correctly.
Figure 3-3
Checking Circuit Current
To determine whether proper current is available for
braking, refer to Table l- Magnet Current Rating.