Allis-Chalmers Crawlers: An Impressive Track Record

Tracing the history of the Allis-Chalmers crawler and its parent companies.

AC Crawler

The Allis-Chalmers HD-11 diesel crawler is shown in this 1957 photo with a hydraulic dozer blade. This mid-sized crawler was built from 1955 to 1970, and was one of the first to introduce the 6-cylinder, 4-cycle Allis-Chalmers/Buda engine.

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I love crawler tractors. I’ve always been a huge fan of them. I think it’s genetic, as my grandfather bought a J-T crawler in 1918 and family members down through the line have been “cat skinners” all along, including my uncle who served with the Seabees in World War II.

The first vehicle I remember driving, at about age 9, was an Allis-Chalmers crawler. My father – a forest ranger – was discing a fire lane, and I was along for the ride. I suppose he got bored with it and offered me the controls. The feeling of irresistible power got hold of me then and has never let go. My dad worked for the Wisconsin Conservation Department, where Allis-Chalmers, one of two major tractor makers in the state (along with Case), was a featured supplier. During World War II, brands such as Cletrac and Caterpillar were also used.

I did own a crawler for a time, a 1959 John Deere 440C bulldozer, and I know that a collectible crawler is more of a commitment than a wheel tractor. They are generally too heavy for your pickup and trailer, they churn up your turf and driveway, and something always seems to be wearing out in the boggie wheels or track pins. Nevertheless, this hobby includes a dedicated group of crawler collectors.

Foundation laid by Holt, Best & Monarch

Soft bottomland soil, mud, hillsides and snow caused traditional wheel tractors to bog down. Enter the crawler tractor with its larger footprint for better flotation and decreased soil compaction. The first of these were made by the Holt and Best companies for farmers in the northern California delta country. Holt and Best eventually merged to become Caterpillar, but crawlers with many other names followed, including Monarch, which was later taken over by Allis-Chalmers.

Monarch Tractor Co. was organized in Watertown, Wisconsin, in 1913. The first products were a 10 hp Lightfoot developed for the smaller farm and a 20 hp Neverslip aimed primarily at the logging industry. Production facilities were in Watertown and Berlin, Wisconsin; Passaic, New Jersey; and Brantford, Ontario, Canada. The company reorganized in 1919 as Monarch Tractors, Inc. Varied sizes were offered, powered by Beaver, Stearns and LeRoi engines. Features included patented double-tooth sprockets, link chain final drive and the use of a steering wheel, rather than levers to release drive clutches for steering. The company again reorganized in 1925 as Monarch Tractor Corp. and moved to Springfield, Illinois. Allis-Chalmers acquired Monarch in 1928.

Good timing moves new company forward

E.P Allis & Co. and Fraser & Chalmers Co. had roots going back well into the first half of the 19th century, but they did not come together as Allis-Chalmers Co. until 1901. A new trademark advertised “A-C the Company of the Four Powers – Steam, Gas, Water and Electricity.” Products included steam power plants, sawmills and mining equipment. By 1913, that diversity led to inefficiencies resulting in bankruptcy and the appointment of a receiver, one Brig. Gen. Otto H. Falk, who was retired from service in the Wisconsin National Guard.

Falk, a scion of one of Milwaukee’s many prosperous German brewing families, reorganized the company, streamlining operations and simplifying product lines. Seeing the future in the tractor business, Falk made tractors his pet project until his retirement in 1932. He hired Harry Merritt to manage tractor activities. In 1928, Merritt acquired the Monarch crawler tractor line. A year later he chose to paint Allis-Chalmers tractors their trademark Persian Orange color.

At the time of the acquisition, the 75 hp Monarch Model F and the 50 hp Model H were in production. The Monarch name was retained for a time, but in 1929 the name was dropped and the characteristic Monarch steering wheel was replaced by steering levers. A-C had several wheel tractors in production, but profits from that line were scarce. The addition of Monarch, Henry Ford’s termination of U.S. production of the popular Fordson, and the 1931 merger with Advance-Rumely (which brought with it an agricultural dealer network) put Allis-Chalmers tractors on solid footing.

Developing new models: A-C K and L crawlers

In 1929, the original Monarch Model 35 (later called the Model K) came out. Aimed at farmers, it was equipped with a rear PTO for operation of balers and other harvesters becoming popular at the time. Under A-C, it was powered by an Allis-Chalmers 4-cylinder engine. An orchard version was offered with the seat and controls moved aft and downward. A K-W wide-track version was also available, as was a K-O model in 1935 (the “O” standing for “oil,” in a version with a semi-diesel engine).

A-C was reluctant to make the switch to full diesels like Caterpillar and International Harvester, and instead used engines with higher compression, but not high enough for auto-ignition. These used fuel injectors and spark plugs burning cheaper diesel fuel, fuel oil or kerosene, rather than gasoline. The K was produced until 1943.

In 1929, the displacement of the LeRoi engine in the Model F was increased by enlarging the bore diameter by 1/4-inch. In 1930, the Model H’s Stearns engine was replaced by an A-C engine with increased displacement.

The all-new Allis-Chalmers Model L (probably standing for “Large”) replaced the Monarch Model F in 1931. At 26,000 pounds, it weighed less than the Caterpillar D-8 (33,000 pounds), produced the same brake horsepower (109), but used half again more gasoline at maximum power than the diesel D-8, although the Model L-O (oil engine) did slightly better on fuel consumption.

Interestingly, the operator station of the L was offset to the left, rather than being in the middle of the cockpit. As on all A-C crawlers of that period, a hand master clutch was used. The L had dual carburetors and exhausts. A canopy was standard, but enclosed cabs were optional. Multiple disc steering clutches were used, probably the best in the industry. Production of the L ended in 1942.

Models M and S meet market needs

The Allis-Chalmers Model M crawler came next, in 1932. It shared its engine with the Model U wheel tractor and was about one-fourth the size of the L. That proved to be the right size for forestry operations and most Midwestern farms. With almost 15,000 sold by the time production ended in 1942, the M was the most popular A-C crawler of the period. The M was offered with wider tracks for hillside operation, and as orchard and logger specials. Gasoline was the standard fuel, but a low-compression kerosene version was an option (started on gasoline and switched over when warm). Engine displacement was increased in 1936 from 301 to 318 cubic inches. A 4-speed transmission was provided. A starter, lights and canopy were optional.

The Allis-Chalmers Model S was introduced in 1937. The S (and the oil-engine S-O) was another large crawler, weighing in at more than 20,000 pounds. It was an 84 hp machine that fit the gap between the 62 hp Model K and 108 hp Model L. The Model S/S-O used a 4-cylinder engine, a 5-speed transmission and a 12-volt electrical system. It was rated for eight 14-inch plow bottoms and could be equipped with a rear PTO or a belt pulley. The gasoline version could easily go through a barrel of fuel in a day’s work. The oil engine was not quite as thirsty and the fuel was cheaper, but Caterpillar and International Harvester were eating Allis-Chalmers’ lunch with their thrifty diesels. For A-C, the diesel handwriting was on the wall.

Allis enters new era with GM Detroit Diesel

Allis-Chalmers finally saw the light in 1940. A new design dropped the oil engine and adapted the General Motors Co. Detroit Diesel 71 Series 2-cycle, blower-scavenged engine to a new line of crawlers. The GM Detroit Diesel engine was first produced in 1938. It was available in both inline and V-configurations, with the inline models including one, two, three, four and six cylinders, and the V-types including 6, 8, 12, 16 and 24. The “71” in the model series designation refers to the cylinder displacement in cubic inches with the bore and stroke at 4-1/2 by 5 inches. Other size series were also available.

Inline models were “symmetrical,” meaning that blower, exhaust, water manifold, starter, etc. could be mounted on either side of the basic block to fit a particular application. A number of models could also run either clockwise or counter-clockwise (and were known as “right hand” or “left hand” engines).

Normally, 2-cycle engines use crankcase aspiration; that is, as the piston continues downward past the intake port, it forces intake air and fuel through the crankcase into the intake port and, at the same time, forces spent combustion products out the exhaust port. In the case of the GM Detroit Diesel engine, only an intake port is used and conventional exhaust valves in the head are provided. A Rootes-type blower is used to purge exhaust gasses from the cylinders and supply air for combustion. It also provides a small measure of supercharging. Later high-performance versions were available with turbochargers, as well. GM discontinued production of this engine type in 1995 in favor of 4-cycle diesels.

Being a 2-cycle engine, the GM has combustion every time a piston comes up. That makes it sound like it is turning twice as fast as a comparable 4-cycle engine. The high-speed firing, coupled with the howl of the blower, generates a sound you’ll not soon forget. Owners loved them because of their dependability and fuel frugality, but operators preferred the mellow, resolute sound of the slow-turning Caterpillar engine. Also, the Cat’s torque curve was relatively flat almost to stall, while the GM engine “fell out of bed” if the rpms were allowed to drop. Operators said that the only way to run one was to be mad at it, and if the tractor had a cab, you should slam your hand in the door a few times to get yourself in the proper mood!

Tractor torque converter unveiled

Allis-Chalmers’ first application of the GM Series 71 engine was in their new 29,000-lb. Model HD-14 in 1939. It used an inline, 6-cylinder version with a total displacement of 426 cubic inches and produced a PTO output of 145 hp. A 6-speed transmission was standard, but in the HD-14C version (after 1946) a 3-speed with torque converter was used, the first use of a torque converter in a tractor. Another first for a diesel tractor: straight electric starting.

Also in 1940, the HD-7 – the smallest of the HD series – was introduced. Weighing in at just under 14,000 pounds, it used a 3-cylinder 3-71 engine and a 4-speed transmission. An agricultural version used a spring front support, while the industrial version did not. About 5,000 HD-7’s were used by the military in World War II and more than 18,000 were built by production-end in 1950.

The third in the pre-war series was the HD-10 with a 4-71 engine and a 6-speed transmission. The 21,000-pound unit was about the same size as the old S-O crawler. PTO horsepower was 98. Electric starting and lights were standard equipment. A belt pulley was an option.

Making the transition to Buda diesel

The years after World War II saw new and innovative crawlers from Allis-Chalmers using the GM Series 71 engine. The “little brother” 6-ton HD-5, introduced in 1946, used a 2-71 engine and a 5-speed transmission. The HD-19 was introduced in 1947; the HD-15 and HD-9 in 1951. Also in 1951, the HD-20 was introduced with a GM 6-110 engine of 175 hp.

The HD-5 was replaced in 1955 by the HD-6. It was similar to the HD-5 except it used a 4-cylinder, 4-cycle Buda diesel engine, A-C having bought Buda Mfg. Co. in 1953. A torque converter and 2-range shifter were options. In fact, as of 1955, the GM Detroit Diesel engine was discontinued from the entire line, replaced by versions of the 4-cycle Buda power plant. 1960 saw the introduction of the H-3 and HD-3 crawlers based on the Allis-Chalmers D-15 wheel tractors. (See the table for details on these Allis-Chalmers crawlers).

Finally, in 1970, the massive HD-41 was unveiled. At that time the world’s largest crawler, the HD-41 weighed in at 101,500 pounds. It was powered by a Cummins turbocharged V-12 engine of 1,710 cubic inch displacement, producing 524 hp. A 3-speed power-shift transmission with torque converter was used. A 20-foot wide bulldozer blade was optional. An online video shows the HD-41 at a tractor pull. The HD-41 was flagged to a stop as it was about to pull the drag apart and leave the fairgrounds. It showed no signs of slowing up to that point.

Allis-Chalmers crawlers had a reputation for dependability and ease of maintenance. Many major sub-assemblies could be removed for service without disturbing their neighbors. The positive-seal bearings for track rollers and idler wheels were permanently lubricated and did not even have grease fittings. Hydraulically assisted steering, in the late 1950s, made the larger A-C crawlers as easy to handle as the smaller ones.

In 1974, Allis-Chalmers merged with Fiat, and then in 1985 it became Deutz-Allis, later Allis-Gleaner, then AGCO, which it remains at this writing. FC


After 36 years in the aircraft industry, Bob Pripps returned to his first love and began writing about tractors. He has authored some 30 books on the subject and several magazine articles. Pripps has a maple syrup farm near Park Falls, Wisconsin. In harvesting the maple sap, he relies on a Ford Jubilee and a Massey-Ferguson 85.