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Performance Based Brake Testing Technology
E-Squared Engineering staff have conducted research and
served in an advisory capacity on the Federal Highway Administration Performance
Based Brake Testing (PBBT) Technology Working Group. This effort was
established to evaluate the effectiveness of various technologies and develop
standards that will help ensure uniform testing procedures. Brake
violations are the number one safety violation on trucks on the road
today. The FHWA, State DOTs, motor carriers, vehicle manufacturers and
insurance companies all realize the positive role that PBBTs can play in
increasing safety - IF they are used correctly. At E-Squared Engineering,
we have the expertise to help our clients understand PBBT capabilities and
limitations - AND we can provide training on how to use them correctly.
Below are some examples/pictures of the Flat Plate
Brake Tester and the Roller Dynamometer Brake Tester.
Flat Plate Brake Tester
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The Flat Plate Brake Tester has 4 plates and measures weight, horizontal, and
vertical forces. Roughly speaking, the test is conducted by having the
driver roll each axle over a plate at a very slow speed and apply the brakes at
full force. The computer, using both the horizontal and vertical forces
measured by the plate sensors, calculates the actual braking force applied at
each axle. This performance based measurement tells the inspection
personnel and the driver the actual braking capability for the vehicle AS
LOADED. This is a departure from current testing measures which can
only predict braking force at an arbitrary design loading. Some
states are using PBBT devices for screening purposes to identify vehicles with
non-functional brakes.
Roller Dynamometer Brake Tester
The roller dynamometer is another PBBT that measures the braking
capability of the vehicle AS LOADED. This system works a little
differently than the flat plate brake tester. The 'roller dyno' works
by connecting pressure lines to the the truck's brake lines (to measure
pressure). The driver then drives each axle on top of the 'roller dyno'
and stops. The rollers on the machine then turn the truck tires (which
are in neutral). The driver is then instructed to slowly apply the
truck's brakes while the rollers are spinning the tires. The 'roller
dyno' measures the physical resistance that the truck's brakes are applying
to the 'roller dyno'. At the same time, the pressure in the brake
lines are measured by the computer system. The computer uses the
recorded pressure in the brake lines accompanied by the physical resistance
that the truck's tires are applying against the 'roller dyno' to calculate
the braking force. This process is repeated for each axle of the truck
to determine the AS LOADED braking capability of the vehicle. Again,
this is NOT a predictive test. It is actually measuring the 'true'
braking capability of the vehicle. In essence, a performance based
test. Two additional important features of this type of machine are that some models are portable (like the one shown), and they can also
diagnose anti-lock braking system (ABS) problems and failures. This
latter point is especially important because ABS tests today consist of
checking to see if a light comes on (predictive test) rather than an actual
test of the ABS brake performance (performance based test).
For more information on PBBTs or how E-Squared
Engineering can help you achieve your organizational goals - give us a call or
type us a note. We look forward to the opportunity. After all, we
can't be successful unless we help our clients become successful - first.
(see the home page for contact information)
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