Big Wheels
IMAGINE GETTING STUCK BEHIND THIS ON A HIGH way. It is twice as wide as a semitrailer and 572 feet long. Its 54 giant rubber tires each stand 10 feet high, and their treads are 4 feet wide. Every wheel contains a DC electric traction motor in its hub; they’re powerful, but they still can’t propel the massive vehicle at more than 20 miles an hour. Fortunately, it was never intended for use on highways. It was designed for off-road transport operations over rough and hilly terrain, and only in very remote corners of the world.
The Jeep and military personnel are there because the giant vehicle had to do with the U.S. Army. It was the product of a joint venture of the Army and the R. G. LeTourneau Company, of Longview, Texas, between 1955 and 1962.
Army studies done at the end of World War II had shown the need for a new kind of transport to serve the highly mobile and fast-moving infantry of the future. The idea of using self-powered wheels was proposed by Robert G. LeTourneau, who had developed big electric wheels for use on all kinds of giant machines, from cranes and gantries to earthmoving equipment and off-road haulers. His electricpowered wheels were ideal for massive multiwheeled vehicles. They didn’t need transmissions, so there was no mechanical loss of power; they ran on electricity carried by cables from onboard generators powered by diesel engines. The Army classified the vehicle as a logistical cargo carrier, and it produced two of the largest rubber-tired vehicles in the world, first the prototype LCC-1 and then the MK-II in the picture.
LeTourneau had been fascinated by big rubber-tired wheels with electric hub motors for years. He had begun his career at a variety of jobs and eventually became an independent contractor on large land-leveling and dirt-moving projects. In 1924 he opened a small factory to build his own machines. He was so successful with innovative earthmoving machinery that his business grew into an international company with five manufacturing plants. The idea of rubbertired, self-powered wheels came early on. Nonpowered machines of the time, such as graders and scrapers, rode on steel wheels and were pulled along by steel-wheeled tractors. Their operating efficiency depended upon soil conditions; loose and sandy ground caused them to bog down frequently, and they weren’t allowed at all on paved roads, over which they had to be hauled on trailers to their job sites. To reduce his hauling costs, LeTourneau gave such machines interchangeable wheels, with rubber tires for towing and steel wheels for the steel wheels for the job.
During one job in Southern California, a contractor became frustrated with the continual bogging down of a LeTourneau scraper machine, and LeTourneau sent him another scraper that had rubber tires only; the steel wheels were left behind at the factory. To the contractor’s surprise, the rubber tires performed trouble-free and in fact got the job done much faster on a fraction of the fuel steel wheels required.
LeTourneau realized that if he could find a way to selfpower such a machine, he would be able to eliminate the tractor that pulled it. He started experimenting with traction motors in the wheel hubs. They worked but weren’t powerful enough. Very large wheels with big powerful motors did not yet exist, and a great deal of research and development work would be required to achieve them.
LeTourneau couldn’t do it. During World War II, the company’s plants were fully occupied making earthmoving equipment for the military. An estimated two-thirds of all the angle dozers, push dozers, scrapers, and rooters used by the Allies in the war were built at LeTourneau plants. When the war ended, he revived his dream of giant selfpowered electric wheels, but he was going to need funding.
In 1953 he sold his earthmoving-machine business to the Westinghouse Air Brake Company for about $30 million. He kept two of his plants, at Vicksburg, Mississippi, and Longview, Texas, but with the understanding that he would stay out of earthmoving equipment for five years. The sale gave him the cash he needed. He poured millions of dollars into R&D and built all kinds of non-earthmoving machines, including log stackers and missile transporters. When he learned of the Army’s interest in developing a huge new transport vehicle for the resupply of Distant Early Warning (radar) stations above the Arctic Circle, he suggested his electric wheels, and the joint venture followed.
He built the prototype LCC-1 at his plant in Longview, Texas, in 1955, meeting detailed specifications developed by the U.S. Army Transportation Research Command. It consisted of an articulated control car with two compartments. The one in front held heated living accommodations for a crew of three. The rear one held electric generators, a 600-horsepower diesel engine, a fuel tank, and a jib crane to facilitate wheel changing and connection and disconnection of cargo cars. The 174-foot-long train traveled on 16 rubber wheels, each 10 feet high and 4 feet across.
After trials on beaches and snowdrifts, the LCC-1 was shipped to the Greenland icecap for exhaustive operational testing while carrying supplies to the Distant Early Warning stations. It became known as the Sno Train. The project team then turned to preparing the MK-II, the Overland Train, which would be much larger and carry more than three times the cargo. Incorporating many improvements and constructed of welded aluminum, it had a control car, 10 cargo cars, and two power-generating plants. It could haul 150 tons of cargo over rough terrain at speeds up to 20 miles an hour for 400 miles without refueling. It generated its electric power in the two end cars using three gas turbine engines that produced a total output of 3,510 horsepower at 1,800 rpm.
The control car now had living quarters for six and an auxiliary engine for independent operation when the car was detached from the train. A single operator controlled it all, using two levers to regulate speed, power, and braking. Steering was done by turning the front axle of the articulated control car. All the other cars automatically tracked and turned on precisely the same spot, thanks to a unique mechanical linkage between each car. The result: the logistical supply equivalent of an entire fleet of 60 two-and-a-half-ton Army trucks.
Following preliminary tryouts in Texas, the big machine was delivered to the Army test station at Yuma, Arizona, and in April 1962 special arrangements were made with the Arizona and California state highway patrols to permit it to travel by highway to the Yuma County fairgrounds for public exhibit. After that it was moved to Ogilby, California, for sand-dune tests. The results were favorable, but the Army was growing concerned over the vehicle’s cost. Also, there were a lot more mechanics than electrical-system specialists in the field to support transport operations. The Army decided to forgo further tests. The MK-II and its prototype were taken out of service.
Today, the Overland Train exists only in memory. Big self-powered wheels are still manufactured, though, at the LeTourneau plant in Longview. They end up on giant LeTourneau machines of many kinds all over the world.
