Today, we ride the world's largest land vehicle.
The University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
If you ever toured the
Kennedy Space Center, you rode a long broad road
from the NASA assembly building (where the shuttle
is put together) out to the launch pad (where the
shuttle lifts off). Actually, that's only one half
of a very special road. Parallel to it, and a
stone's throw away, is an identical road. The
surface of both is loose stone, with a far deeper
substrate than you'd expect.
Actually, each of those parallel roads carries one
side of the world's largest land transport vehicle.
It's a machine called a Crawler Transporter,
originally created for NASA to carry an assembled
Saturn rocket on its five-mile journey from the
assembly building to the launch pad. And the Saturn
is even larger than the Space Shuttle with its
The Crawler makes more sense as an engineering
accomplishment when we digest the magnitude of the
task. It was designed to carry a
twelve-million-pound rocket and launching derrick
and to keep them within ten minutes of an arc from
pure vertical while it negotiates grades of as much
as five degrees.
This mode of transport was selected in preference
both to a special barge-and-canal system and to a
rail system. What finally emerged was something out
of science fiction. It's 131 feet long and 114 feet
wide. It weighs six million pounds. The structure
rides on four double tracks, each pair the size of
a Greyhound bus. Inside its huge deck are diesel
engines with a total output of almost eight
thousand horsepower. They drive generators that
supply electric motors for the tracks, for the
delicate leveling mechanism, for the cooling
systems, and for other internal functions.
The five-mile journey to the launch pad takes a
highly trained crew of eleven people: a driver,
four observers at different locations who advise
the driver on steering, and six technicians. The
Crawler moves two miles an hour unloaded and one
mile an hour with the rocket in place. Its fuel
economy is about 1/150th of a mile per gallon.
And who do you suppose built this high-tech
behemoth? Actually, two were built originally, and
they were not products of the aerospace industry.
The Crawlers were made for NASA by the Marion Power Shovel Company in
Ohio, a company with experience in heavy
earth-moving equipment. The crawlers cost fourteen
million dollars each in 1967, the year they went
The Crawler Transporter is the twentieth-century
spawn of engineers like Brunel, Eiffel, and
Roebling. Now we leave their heroic 19th-century
renderings in iron, and we take up a technology of
speed, space, and light. The rocket reaches for the
heavens while we and the Crawler stay
gravity-bound. It calls up all the unbearable
contrast of the rocket itself, as it becomes a
golden speck in space.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
The American Society of Mechanical Engineers (ASME)
named NASA's original Crawler Transporters as a
National Historic Mechanical Engineering Landmark on
Feb. 3, 1977, at the John F. Kennedy Space Center.
Information for this episode was originally obtained
from the dedicatory brochure for that ceremony and
later expanded by a great deal of NASA material.
This is a greatly revised version of Episode 25.
The Internet offers a great deal of information
about the Crawler Transporters. Their history is
told by NASA at:
This NASA photo shows Space Shuttle Columbia
leaving the assembly building aboard a Crawler:
This is a NASA photo of a Crawler arriving at the
launch pad with Space Shuttle Discovery aboard it:
And here is a great closeup of the Crawler
For information about the Marion Power Shovel
Photo by John Lienhard
Two one-ton cleats from one tread of the Crawler
The Engines of Our Ingenuity is
Copyright © 1988-1998 by John H.
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