When a country goes to war, it’s army needs more than bombers, tanks, cannons, rifles and ammunition. Those are part of what makes the tip of the spear but the best spear tip is of no use without the shaft that carries it to the enemy. That shaft is made up of everything from apple sauce to zerox ink. During World War II, one of the many items making up the shaft was the Heavy Tractor, M1 (IHC TD-18), a military version of the International Harvester TD-18 crawler.

The first TD-18 rolled off the line October 20, 1938 and sales began in 1939. The TD-18 was the big boy in the IH “TracTracTor” line. It had their biggest six-cylinder tractor diesel of the day, the 691 cubic (TD-18 later called the D691), and was designed to compete with the Allis-Chalmers L and others in the big crawler market. Cat would challenge it in 1940 with their D7 and Allis-Chalmers with the HD10W and HD-14 in 1939 and 1940. Anticipating war in some form, an American rearmament push began in the late 1930s and that push included crawlers. It got very much more serious when World War II began for the U.S. on December 7, 1941.


The IH 691ci 6-cylinder diesel debuted about the same time as the TD-18. It was a part of International’s second generation family of diesels and they pushed them in a big way. It had a 461ci, 68 brake horsepower, four-cylinder little brother with the same bore and stroke that was used in the TD-14 crawler and other applications. The 691 saw use in a great many applications beside the crawler, including marine and stationary operation. It was a wet-sleeved, indirect injected, seven-main bearing six and weighed in at 2805 pounds. At 1400 rpm, it made 103 hp. It was rated at 84.66 belt horsepower by IH and 80.44 at Nebraska in a 1938 test but in civilian use, they only ran them to 1200 rpm. The engine was revised several times in it’s long life, to about 1958, and was listed at 125 hp at 1600 in 1958. Like all the period IH diesels, it started on gasoline and then was switched over. It had a direct driven air compressor used for an air brake system fro trailed equipment.

Crawlers of all types and brands had been in widespread use by the U.S. ground forces since World War I. With the combat arms, they were used as artillery prime movers in difficult terrain for big guns like the 155mm. They were also employed as heavy recovery vehicles and for dragging pallets of supplies off a beachhead. Of course they also saw more normal use in construction work, with or without a dozer blade.

The TD-18 was seen in uniform as early as 1940 and was categorized as Heavy Tractor, M1 (IHC TD-18). That last bit was necessary because there were two other “Heavy Tractor, M1” from other makes, namely the Allis-Chalmers Models L (early on) and HD-10W, and the Caterpillar D7. The TD-18 Ordnance Tractor variant came in several different forms during the war, Lots 1, 2, 3 and 4. We could not find all the differences between them, but it’s known the Lot 1 tractors were essentially civilian tractors with a single speed front winch. Lots 2 thru 4 had many updates mandated for government service. Among these were an extra-wide, four-person seat. The winch changed to one with two spooling in and one spooling out speed and the Lot 4 tractors had dual fuel tanks, 120 gallons total.

The front winch in the Lot 4 tractors was a 30,000 pound Gar Wood and it had three speeds, two pulling in and one going out. It carried approximately 300 feet of 3/4 inch wire rope. The winch was used for recovery and moving the large field guns.


This is how the tractor will look when complete. This is a Lot 3 tractor but the difference between Lot 3 and 4 are not apparent until you see the back. The Lot 4 tractors have a second fuel tank behind the existing, about where the bustle basket is now. Note the second pintle hitch about the drawbar. The tractor came with an air system to operate the air brakes on the field guns.

The basic TD-18 was used in many roles during the war, but we are mainly talking about Ordnance Tractors, those used by an artillery branch of either the Army or the Marine Corps. They were typically used to pull either the 155mm M1918 gun, the newer 155 mm “Long Tom” gun or the 8-inch gun over rough terrain. The TD-18 had a top speed of just under 10 mph, so if the guns needed to move fast over roads or longer distances, a heavy 6×6 truck like the Mack NO 7.5-ton might be used. Later the M4 high speed tractor became more common. The Marine Corps used the TD-18 to good effect in the Pacific. As they fought from island to island towards Japan, seldom were there roads and the ground was often soft or sandy, so the big crawlers were needed to drag the field guns into position.

This is the typical load for the M-1 Ordnance tractor, the legendary M-1 155mm Long Tom. It had a 6.1-inch bore and could fire a 45 pound round at 2,800 feet per second up to 15 miles. It fired eight different types of projectiles using bagged charges.. The Armor Piercing round could penetrate up to 7.7 inches of armor plate and the HE round could blast through 6.5 feet of concrete. Rate of fire is listed at 40 rounds per hour, served by a crew of 14. The complete assembly weighed 30,500 pounds. Dsdugan

The tractor shown belongs to Adam Voght. He bought it as a derelict tractor in 2000. It’s a ‘42 Lot 4 tractor built for the Ordnance Branch of the U.S. Army. It’s military history is unclear, but Adam thinks it was operated out of the Jefferson Proving Grounds, near Madison, Indiana, and sold surplus from there. The likely buyer was a nearby coal fired powerplant who converted it into a bulldozer and used it to push coal. Some sources list as many as 7,500 TD-18s in various configurations being built for the war effort. The TD-18 model lasted through several upgrades and evolutions into the late 1950s.

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