Donaldson Company: Meeting Tougher Standards in a Noisier World
16 March 1999
Donaldson Company: Meeting Tougher Standards in a Noisier World
MINNEAPOLIS, March 16 -- As noise pollution becomes an
increasing concern, the trucking industry faces growing vehicle noise
regulations on federal, state and local levels. The Donaldson Company's
new Silent Partner silencer, introduced Sunday evening, will help
truckers to effectively meet -- and surpass -- these requirements in a cost-
effective manner.
The modern world is a noisy place -- and it seems to be getting louder.
On a daily basis, we're subjected to louder, harsher sounds from sources as
diverse as jet aircraft and boom boxes. Loud noises aren't just uncomfortable
and annoying -- they've been proven to be hazardous to health and quality of
life. Besides hearing loss, loud noises can cause or aggravate conditions
like high blood pressure, stress, anxiety, insomnia, and nausea. And
prolonged exposure can result in everything from chronic fatigue to reduced
workplace performance and lost productivity.
In response to this growing din, federal, state, and even local regulators
are enacting ever-tighter noise restrictions. And one of the areas they have
concentrated on is heavy-duty trucks.
EPA standards only address loudness, and not noise quality. But a growing
number of municipalities have stepped in to draft regulations designed to
control unpleasant noises within their jurisdictions. Again, trucks have been
singled out -- for the loud, rasping sound made during engine braking. As a
consequence, "No Engine Brake" signs are becoming a frequent sight along
United States and Canadian roads.
Vehicle noise raises yet one more concern: driver performance and health.
Drivers frequently exposed to exceptionally loud noises, such as engine
braking, can contract the health problems listed above. Also, sharp, loud
noises distract the attention of the driver behind the wheel, and disrupt the
sleep of an off-duty driver. Besides possible safety risks, other
consequences can include driver dissatisfaction and potentially increased
workman's compensation costs.
The entire industry, as well as individual fleets, can ignore this issue
only at their own peril. Non-compliance with noise regulations means more
than citations and fines. It is already leading to an increase in additional
regulation, most notably the bans on engine braking. And every excessively
loud truck on the road serves to aggravate trucking's already embattled image
with the public.
To meet increasingly stringent noise control requirements, truckers have
resorted to several alternatives, none of which have proven truly
satisfactory. Exhaust brakes reduce engine braking noise, but also limit
engine braking performance. Bigger mufflers provide some relief, but at a
sizable weight penalty. And better cab insulation helps drivers, but does
nothing to reduce drive-by noise.
There had to be a better solution. And after years of research, design,
and testing, Donaldson engineers created it: the Silent Partner silencer, the
first muffler-type product designed to decrease the distinct noises produced
during acceleration and engine braking.
Although it shares the same exterior dimensions as conventional mufflers,
Silent Partner technology is so different that its design and performance
claims are patent pending. The unique Silent Partner combines, for the first
time in a diesel exhaust product, four separate acoustic technologies that
comprehensively reduce noise levels -- while at the same time "shaping" harsh
engine braking sound into a warmer, more pleasant tone:
* Reactive silencing creates sound waves that actually cancel out the
unpleasant noise frequencies created during engine braking.
* Resistive silencing reduces low frequency exhaust pressure variations
that help create the distinctive "barking" sound made by engine brakes.
* Adsorptive silencing reduces sound levels by transforming sound energy
into thermal energy.
* Body shell noise dampening keeps the Silent Partner shell from vibrating
and resonating -- a source of exhaust noise with conventional mufflers.
Consequently, Silent Partner provides a level of noise control which
standard mufflers simply cannot match. Silent Partner greatly reduces both
acceleration and engine braking noise. Most notable is the braking noise
reduction. A Silent Partner-equipped truck during engine braking is barely
louder than a conventionally-muffled truck under acceleration!
As important as the reduction in noise level is the improvement in noise
quality. The four acoustic control technologies smooth out the rough octave
bands produced by engine braking, thereby eliminating the harsh sound that has
led so many communities to ban engine brake use.
Silent Partner will allow fleets to meet current and future noise
regulations in an efficient, reliable, and cost-effective manner. For any
fleet that's serious about maintaining fleet compliance, driver satisfaction
-- and company image -- it will be absolutely essential.