Braking Units
Part 1 “Brake Box”
There are several brake boxes available for
your towed vehicle.
Blue Ox, Roadmaster and Brake Buddy are 3 examples.
A brake box is a simple to use device that sits on the front driver’s floor of
the vehicle.
They are powered from a 12 volt outlet or can be hard wired if an outlet is
inconvenient or doesn’t exist.
These boxes operate from an inertia mechanism within the box. There are some
differences between manufacturers.
Analog electronics were used early on, but now digital has become popular.
Digital control allows the braking unit to react quicker and apply the brake
more “in sync” with the RV.
The unit operates similar to trailer surge brakes. This means it senses
movement.
When your RV momentum slows, the inertia switching device within the unit senses
a decrease in speed and activates the braking unit
which applies the brake pedal in the towed vehicle. The braking units use air
pressure supplied from an internal air pump to apply the brakes.
The air pump operates from a 12 volt DC power source, hence the need for a 12
volt connection.
The amount of brake effort depends on the momentum change. This is where it gets
complicated.
Manufacturers have been trying to make the braking units operate similar to the
RV’s brakes.
Since there is no actual connection to the RV’s brakes, it is difficult to do.
Technology has helped to make these units
operate closer to the RV’s braking. The latest units now use electronic controls
inside the RV to allow driver input.
*Breakaway
A breakaway is a safety device connected to
the towed vehicles braking system.
It also attaches to the RV at the rear by cable. If the towed vehicle would
disconnect from the RV while towing,
the breakaway pin will be pulled by the cable activating the braking system.
Breakaways are required by law in some states and Canada. Breakaways may be
optional with most systems.
This is an item that will be mounted and hard wired to the towed vehicle. It
needs to be center mounted at the front.
I always try to mount it on the base plate when possible. It should be screwed
on and double nutted to allow it to rotate from side to side.
This will help align it to the RV no matter which way it could move if detached.
There are 2 wires that will run from the breakaway to the braking unit.
Be sure to have a professional install the breakaway if you’re not sure how to
do it correctly.
Typical installation takes 1-2 hours. It is the most difficult part of the brake
box installation.
Advantages of braking boxes
Versatile: Can be transferred easily between
vehicles
Ease of installation: Can be self installed.
* breakaway may be required
Disadvantages of braking boxes
Battery run down in towed vehicle: In my
opinion, manufacturers of braking units in general tend to exaggerate battery
run down.
My experience has been that braking units tend to cause battery run down much
quicker than manufacturers disclose.
We typically see battery run down occurs daily from braking units powered from
the towed vehicle.
Brake control: Brake boxes don’t have direct
control from the RV.
Relying on inertia can make the braking unit activate when not wanted. (I have
also seen the braking units “hang” on and not release)
Breakaway switches tend to rust and corrode
in winter driving conditions. About the Author: Mike Wilson is a RVDA Certified Master RV Tech. Mike has 25 years experience as an RV Technician and now he's sharing his
knowledge with you. Mike is the president of Wilson RV and
developer for The RV Help Desk
Articles are based on the best professional judgment and experienced opinion of the writer. Neither
Wilson RV nor the author accepts any liability as a result of provided information.
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