Ummm.. thanks, but that article was posted yesterday, and is what started
off this whole Washboard debate! However, it is good to see that the DML is
becoming much more efficient. We've managed to take the washboard debate
full circle in less than 24 hrs. Very impressive!
Heck, the old 'hand out the window' modification/discussion lasted probably
2 months!
later,
Duff
'95 SLT 4x4 CC 318 4spd/OD - 3.55 LSD
MSD 6AL - MSD Blaster Coil
MSD 8.5 wires - K&N FIPK - F&B Stage I TBI
-----Original Message-----
From: Barret, Matt [mailto:MATT_BARRET@earthtech.com]
Sent: Thursday, March 16, 2000 7:48 AM
To: 'dakota-truck@buffnet.net'
Subject: DML: RE: Washboard...
Ok people, I've seen some pretty humorous answers on this, but here's the
scientific reason.!!
Keith Mather, who was studying nuclear physics in Australia in the early
1960s, wasn't satisfied with the theories of the time: that washboard roads
were caused by "peculiar" soil, wind from passing vehicles, car exhaust, or
impulses from car engines. He doubted all these possible causes because he
noticed that many different surfaces, such as train tracks and ski trails,
also can be afflicted with tiny roller coaster patterns.
Mather set up an inexpensive experiment at his lab in Melbourne. He
assembled a contraption in which a tire connected to a central arm moved in
a circle like the second hand moves on a clock. He covered the floor with
sand and sent the wheel, which was about the size of a lawnmower roller,
circling around the track.
He described the homespun project in his article: "We moved the wheel around
the track by putting a finger behind the shaft and pushing it around the
(track) to the beat of the family metronome. Greatly to my surprise this
produced fairly regular little corrugations several inches apart in the
sand." Mather found that washboard roads developed not only in sand, but
also on "roads" of rice grains, sugar, and split peas. The key, he found,
was that the surface was dry, as Alaska roads often are in the spring.
The faster he spun the wheel, the faster washboard appeared. With repeated
passes of the wheel, he watched the road ripples multiply like snowshoe
hares.
He noticed several keys to the formation of washboard roads: the road
surface had to be non-rigid; the road had to be dry; and washboard tends to
form just beyond an irregularity in the road surface, such as a bump, dip or
small rock.
Bumps in the road surface cause the tire to hop in the air. When the tire
crashes down, it forms valleys by spraying sand and gravel forward and
sideways. The moving tire ramps out of the valley and hops again. Thus, the
washboarding process repeats itself.
The washboard design spreads across the road when other cars repeat the
action of the car that initiated it. Mather pointed out that bumps cause
cars to react in the same way even though vehicles come in different weights
and sizes, and with various suspension systems. He concluded, sadly, that
other than slowing to about 5 miles per hour or using balloon tires to
cushion the road, there isn't much drivers can do to prevent washboard roads
from forming. Mather, who is now 74, retired, and living in Eugene, Oregon,
said he still has heard of no solution.
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