B
ringing the combined weight of a boat, trailer and tow
vehicle to a halt safely typically requires more than the
tow vehicle’s brakes alone can provide, which makes the
selection of your trailer’s braking system critical. Here’s
the low-down on trailer braking systems, along with some
pros and cons for each.Braking 101
The two most common trailer brake systems are hydraulic surge
and electric. Surge brakes are a self-contained, hydraulic system
that uses the weight and forward momentum of the trailer to
activate the brakes. Surge brakes use a brake actuator that is
part of the trailer coupler. When the tow vehicle slows down,
the trailer pushes against this actuator, compresses a hydraulic
cylinder and automatically activates the trailer’s brakes.
Surge brakes are more expensive than electric brake
systems; however, they require neither a brake control
(mounted at the dash of the tow vehicle) nor an electrical
connection to the tow vehicle in order to operate. This
simplifies the installation and means any suitable vehicle
can tow them without the need for additional equipment.”
On the downside, this lack of connectivity to the tow
vehicle means that a driver cannot directly control surge
brakes — a feature many electric brake systems provide.
Electric brakes use power from the tow vehicle to actuate
electromagnetic brakes. Unlike surge brakes, electric trailer
brakes are electrically connected to the tow vehicle and utilize
a dash-mounted brake controller. The controller automates
the brakes so they work when the brake pedal of the tow
vehicle is depressed. The controller also allows the driver
to manually activate the trailer brakes when needed, for
example, to address trailer sway while towing or to prevent
a heavy boat/trailer package from dragging a lighter tow
vehicle down the launch ramp; surge brakes don’t operate
when backing down an incline.
While electric brakes are less expensive than surge brakes
when initially purchasing a trailer, they do require the
above-mentioned brake controller — an additional expense
if the tow vehicle doesn’t already have one.Drum vs. disc brakes
Drum brakes consist of three key parts: A wheel cylinder (for
hydraulic systems) or electromagnet (for electric systems), curved
brake shoes and a drum. When the brakes are activated, fluid is
directed to the wheel cylinder, which expands and pushes the
shoes outward against the inside of the rotating drum.
With electric drum brake systems, pressing the brake pedal
sends an electric current to the electromagnet, which then
pushes the shoes outward, engaging the inside of the drum.In both systems, once enough force is applied to the
drum, the trailer stops.
Disc brakes similarly have three major components:
Calipers, pads and rotors. The rotors are also attached to
the wheels, but while the drum encircles the brake assembly,
rotors are flat or “disc” shaped (hence the name) and are
visible while spinning. The calipers (which hold the pads)
“float” alongside the rotor and contain inward-facing pistons.
When the brakes are pressed in a hydraulic system, fluid
fills the calipers and pushes the pistons out, pressing the
pads against the rotor. An electric system works in a similar
fashion but uses an electric current rather than fluid.
Although drum brakes have benefited from advances
in design and materials, they’re still old school technology
compared to disc brakes. In fact, the primary advantage of
drum brakes is their cheaper cost, which is why many trailer
manufacturers continue to provide them as standard equipment.
Disc brakes provide superior stopping power, but they
also have a number of other benefits over drum brakes — a
big one being better heat dissipation. Stopping a heavily
loaded trailer generates a lot of heat. Excessive heat buildup
in drum brakes can lead to a condition known as brake fade,
which causes the brakes to lose effectiveness during long
downhill runs. Excessive heat can also cause the drum to
expand, meaning that the shoes have to travel further to
engage it; this also reduces the brake’s efficiency.
Disc brake rotors are exposed, allowing them to cool as
they spin, which eliminates the heat-related issues drum
brakes suffer. Being exposed also makes the parts of a disc
brake easier to rinse and inspect; drum brakes have to be
disassembled for inspection.
Finally, discs brakes tend to self-clean themselves as they
press against the braking surface, and when the trailer is
submerged, the exposed, spinning rotors are better at ridding
themselves of water.Electric over hydraulic disc brake system (EOH)
When towing larger trailers carrying heavier boats, the
best choice is an electric over hydraulic (EOH) disc brake
system. The EOH system replaces the surge-activated brake
solenoid with an electrically operated unit that’s operated
by a brake controller located in the tow vehicle. When the
tow vehicle brake pedal is pressed, the brake controller
sends an electrical signal to the trailer brake actuator, which
then pumps hydraulic fluid to the disc brake calipers and
engages the brake pads.
In addition to providing greater stopping power, an EOH
system also permits driver control and modulation of the
brakes for smoother stopping. ★ PHOTOS BY CAPT. FRANK LANIERby Capt. Frank LanierDON’T HESITATE TO RENOVATE
CAPT. FRANK LANIER
is an award-winning journalist,
boat maintenance guru and
owner of Capt F.K. Lanier &
Associates, Marine Surveyors
and Consultants
(CAPTFKLANIER.COM).(Top) Surge brakes use an
actuator that’s part of the
trailer coupler to engage the
brakes when the tow vehicle
slows. (Above) Disc brakes
provide superior stopping
power and better heat
dissipation, which are two
big advantages over drum
brakes.28 JULY 2017 | LAKELANDBOATING.COMBreaking Down Trailer Brakes
Hydraulic surge or electric brakes? That is the question.
Renovations_JUL17.indd 28 5/25/17 9:33 AM