ON THE VEHICLE
How Well Do You Know
Brake Systems?
By David A. Kolman, Editor
18 Fleet Maintenance | JULY 2017
he proper operation of a vehicle’s braking system
is essential for safety. Th is begins with specifying
the appropriate brakes for the vehicle’s application,
duty cycle, service environment, etc. Th en,
the system must be well maintained for the life of
the vehicle. Otherwise, braking performance – and
highway safety – can be compromised.
When spec’ing brakes for trailers, there are
diff erent considerations to take into account,
according to Marty Watterson, fi eld service manager,
trailer division, Meritor (www.meritor.com), a
leading global supplier of drivetrain, mobility,
braking and aft ermarket solutions for commercial
vehicle and industrial markets. It’s important to be
aware of several key things, including:
• Trailer application and maximum payload.
• Trailer drive cycle – how it will be used – and
duty cycle – how much it will be used.
• Operating considerations, such as environment,
roads and terrain encountered, etc.
• Gross vehicle weight (GVW).
• Axle capacity.
• Sizing the brakes to meet the specifi c load carrying
requirements of a trailer can improve the tractor
trailer’s average stopping distances. What’s
more, properly distributing the work between the
tractor and trailer minimizes thermal overload of
the trailer brakes.
During panic stops, especially on a heavily loaded
tractor trailer, the load shift s from the trailer
axles to the drive and steer axles. Th e harder the
stop, the more the load transfers from the rear of
the rig to the front.
Disc versus Drum
Disc and drum brakes have been used in combination
on tractors and trailers “successfully for
many years,” notes Meritor’s Watterson.
Th e company acknowledges that the use of split
systems, particularly for the cost conscious fl eet,
can be a practical approach.
Things to keep
in mind when
T specifying
brakes
» Meritor EX+ air disc brakes have a wear
indicator mechanism which can provide
an effective visual indication of pad
wear without removing the wheel.
Photo courtesy of Meritor
UNDER VEHICLE