Airstream INTERNATIONAL TRAILER Owner's Manual page 48

AIRSTREAM INTERNATIONAL TRAILER OWNERS MANUAL
HOW ELECTRIC BRAKES HELP
Electrically actuated brakes have several advantageous features over other brake actuation systems.
1. They can be electrically adjusted to provide the correct braking capability for varying road and load
conditions.
2. They can be modulated to provide more or less braking force, thus easing the brake load on the towing
vehicle.
3. They have relatively no lag time from the moment the tow vehicle's brakes are actuated until the trailer
brakes are actuated.
4. They provide a separate braking system to that of the tow vehicle, which can be of benefit in the event of
tow vehicle brake failure.
HOW TO USE YOUR ELECTRIC BRAKES PROPERLY
Your trailer brakes are designed to work in synchronization with your tow vehicle brakes. Never use your
tow vehicle or trailer brakes alone to stop the combined load.
Your trailer and tow vehicle will seldom have the right amperage flow to the brake magnets to give you
comfortable, safe braking unless you make proper brake system adjustments. Changing trailer load and
driving conditions as well as uneven alternator and battery output can mean unstable current flow to your
brake magnets. It is therefore imperative that you maintain and adjust your brakes as set forth in this
manual, use a properly modulated brake controller, and perform the synchronization procedure noted below
In addition to the synchronization adjustment detailed below, electric brake controllers provide a
modulation function that varies the current to the electric brakes with the pressure on the brake pedal. It is
important that your brake controller provide approximately 2 volts to the braking system when the brake
pedal is first depressed and gradually increase the voltage to 12 volts as brake pedal pressure is increased. If
the controller "jumps" immediately to a high voltage output, even during a gradual stop, then the electric
brakes will always be fully energized mid will result in harsh brakes and potential brake lockup.
Proper synchronization of tow vehicle to trailer braking can only be accomplished by road testing. Brake
"lockup, grabbiness, or harshness" is quite often lack of synchronization between the tow vehicle and the
trailer being towed, too high of a threshold voltage (over 2 volts), or under adjusted brakes.
There are two synchronization adjustments available:
1. *System Resistor - regulates the maximum braking power of the trailer brakes.
2. Brake Controller - controls the tow vehicle brake line pressure at which the controller will begin to pass
current to the trailer brakes.
*Note: Electronic brake controller systems now being manufactured have eliminated the need for the
System Resistor and are not hooked directly to the tow vehicle's brake master cylinder. Modern vehicles
with ABS brake systems do not recommend connecting a hydraulic line to their master cylinder. Please
disregard references to the System Resistor if you have an electronic brake controller in this category.
Check with your controller installer or the manufacturer if you have any questions about the need for a
System Resistor.
Before any synchronization adjustments are made, your trailer brakes should be burnished-in by making
10-12 full stops from approximately 20 mph. This allows the brake shoes and magnets to slightly "wear-in"
to the drum surfaces.
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