Custom Rigs Pro Tips
solving a dyno tech problem
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Pro Tech_OVD0113_PG.indd 1
12/13/12 10:19 AM
Bruce Mallinson
hose of you who have
is the owner
not watched chassis
of Pittsburgh
Power, an engine
dyno operators prepare a
performance
shop in
truck for testing might not
Saxonburg, Pa.
realize that a large chain
around the rear differential and 2-inch front tire straps
with ratchet binders are all that hold the truck in place
during a dyno test. This binding method, which is the
standard in the industry, has some associated problems.
First, there is no weight on the fifth wheel. If the truck
produces high horsepower or has bald tires, there will be
slippage on the dyno rollers, making accurate readings
impossible.
Also, binding the truck with chains is time-consuming,
and the differential chain can chip the differential's
paint. If the truck has a custom rear bumper that is close
to the ground, it may be impossible to put the truck on
the dyno.
My friend Al Hemerson – a farmer and owner-operator
from Iowa – came up with our solution: a floor-mounted
hydraulic apparatus that connects to the fifth wheel
through an extendable boom.
I took his drawings to another friend, Jon Anderson,
who is a welder and fabricator, and told him what I
wanted.
After several months of development, we now have
the world's only chassis-binding system of its kind: The
Anderson-Hemerson hitch, or as some around the shop
call it, The Giraffe. This new
chassis dyno binding system
hooks into the fifth wheel and
can pull the truck up onto the
dyno's rollers to the exact spot
where you want it.
The Giraffe even can pick
the back of the truck up off the
ground, move it to the right or
left and put as much as 100,000
pounds of pressure down on the
drive tires.
We have found that 3,000
to 4,500 pounds of downward
pressure does a great job of
simulating the trailer and stabilizing the truck for a perfect
dyno run with close to real-world
results. Parasitic losses in drive
tire alignment, tire tread pattern
and wheel bearing losses are
observed more accurately with
pressure on the fifth wheel.
— Bruce
42 | Overdrive | July 2013
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6/27/13 5:59 PM
