THE 200-TON ROLLER

The 200-ton roller

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New Ashford, Massachusetts 01237

An article on fairly modern tractors and equipment, 1950 era, may seem out of place in an old engine magazine; however, articles of this type do approximate points on the development curve line for this type of mechanical power. By projecting this line, taking in the effects of fuel scarcity, conservation, economic and environmental conditions, one can envision nuclear and solar electric powered tractors operated by a computer while owners are out playing golf or fishing. On the other hand numerous high-priced studies may discover a renewable fuel and renewable power formerly known as hayburning horse and mule power, so let us get back to an old subject: the 200-ton roller or compactor and diesel powered tractors.

Pneumatic tired rollers of various types and sizes up to 100 tons had been around since before World War II but the 200-ton is a one-of-a-kind especially built for testing and producing maximum compaction of the subgrade for the heavy duty runways required by the then new B52, a military plane weighing 207 tons fully loaded, and the new line of large cargo and passenger carrying jet planes. To support planes of this size and value, pre-testing is a must as one cannot afford a failure under use. So the specifications called for six passes, one on top of the other, of a 200-ton roller on a forward and reverse pattern over every square yard of the subgrade. This is the cut or fill grade that is prepared for the base courses and pavement. It is based on the old professor's accolade, 'A road is only as good as its foundation.' Therefore, if the subgrade will support a 200-ton roller now, when gravel and base courses and 18-24 inches of pavement are added, it will support 200 plus ton planes in any weather condition. We did pick up numerous weak areas which had been readily passing a 25-ton roller. Some areas did not fail until three or four passes were made. Then the bottom fell out and it was quite a job to pull out a 200-ton roller! Of course, all areas were corrected and re-tested.

By referring to photo #1, notice the method of assembly to move the roller from one job to another required three flat cars, one for each two-wheel half-section and one for the front drawbar, rear connecting link and pig iron ballast. When assembled empty, it weighed 125 tons, then 75 tons of ballast equaled the 200 tons. Space was also available for another 50 tons of ballast, if needed.

Both Allis Chalmers HD 21s and Caterpillar D8s were used for hauling. They were the big boys at the time and quite common on construction jobs. If any buildup of earth formed in front of the roller wheels two tractors were required, one pulling and one pushing. After the surface ironed out, one could haul it forward but could not begin to back it without jack-knifing, so the rear tractor on a quick cable hookup was used as it could be quickly unhooked and used as a pusher if necessary. Did all this pay off? Yes, after 24 years of use by yesteryear's planes, the B52 is now becoming obsolete, and after today's larger planes, this runway held up remarkably well.

The locale is Westover Field, Chicopee Falls, Mass. The construction is a 300 X 10,000 foot (three hundred plus feet wide and 10,000 feet long) runway with a 1,000 foot paved overrun on each end, actually over 2 miles long, with one of the world's largest hangers, fuel tank farm and pumping facilities. The time 1954-1956. Yours truly was resident engineer in charge.