TC-12 Dozer: The Legendary 1964 Euclid

Euclid TC-12 Dozer

Companies take a big risk when they introduce something radically different than the norm. When the historical smoke clears, which might be decades down the road, they will be judged heroes or zeros. The legendary Euclid TC-12 dozer, introduced for 1955, was a big departure from the crawler norm. It was designed to knock Caterpillar off it’s dominant perch in the crawler industry but didn’t succeed at that. That doesn’t automatically place it in the zero category.

The story begins in 1952, when GM began hiring engineers with expertise in crawler design. That signaled the industry GM was getting in the game. One of the notable GM hires was R.C. Williams, who was Assistant Director of Research at Caterpillar. Williams had been there since 1935 and was well versed in crawler technology. GM didn’t have an official “crawler division” at the time, so he worked in the GM Truck and Coach Division building the foundations of a new division.

Here you can see how the tractor is split. Look carefully, and you can see the stacks are at different levels meaning the tractor is oscillated.

The project gained big momentum in 1953 when General Motors bought the Euclid Company, of Euclid, Ohio. As a company, Euclid went back to 1907 as Armington Electric Hoist Company, later renamed Euclid Crane and Hoist Company, founded by George A. Armington (1865-1954). In the 1920s, it had branched out into earthmoving equipment and Armington’s five sons helped run the growing and expanding company as it came to dominate parts of the construction equipment industry.

By the early ‘50s, Euclid was still successful but needing an influx of cash to stay dominant. It was also suffering from aging leadership looking to live a quieter life. GM, in its usual fashion, wanted into the business realm Euclid largely dominated and the best way was to buy an existing company in that realm. A deal was reached. George, in his late 80s by then, oversaw the sale, and his youngest son, Ray, stayed on to manage the Euclid Division of General Motors until his retirement in 1960. With the merger, R.C. Williams transferred from the Truck and Coach Division to become the manager of Crawler Tractor Engineering at Euclid.

An interesting side to the TC-12 development was that GM assigned a stylist to the project. Charles M. Jordan was at the beginning of his long and storied career with GM and is probably best known for being the Chief Designer for Cadillac in the 1960s and later GM’s overall Chief Designer in the 1980s.

It’s been said operating a TC-12 is “different” but relatively easy to master and with maneuverability that was a delight. The TC-12 could pivot in place, among many other attributes. Having two engines and transmissions, it has two sets of controls and gauges. Plus the stereophonic sound only a pair of Screamin’ Jimmies can deliver. The TC-12 could be steered via the brakes or the throttles, as well as each transmission. It had three transmission ranges (plus the torque converters) in forward or reverse.

The first two prototypes were operational in 1954 and underwent extensive tests. Later that year, ten more preproduction units were built and loaned to construction outfits around the country for further testing. By the middle of 1955, the first retail units were going out to customers and the marketing people went into overdrive highlighting the TC-12’s many unique features. And they had plenty to tout, including “Dual Power.” TC-12 was powered by no less than two GM 6-71 diesels, each powering one track through an Allison Torqmatic transmission. The powertrains were completely separate, and the tractor was divided into halves that oscillated longitudinally and independently of each other. This differed from more conventional crawlers where the track frames are allowed to oscillate independently.

Even though the pair of 6-71s were conservatively rated at 194 hp each (at 1800 rpm), having 338 total horsepower on tap made the first series TC-12 the most powerful crawler in the world. Even the mighty D9 Cat, recently introduced, had only 287 ponies. With the separate Allison gearboxes, the TC-12 operator could keep one track going ahead and put one in reverse for unparalleled maneuverability and control. The gearboxes had three ranges, the highest of which could run the TC-12 to a blistering top speed of 6 mph (later up to over 7 mph) and at the same speed forwards or back.

In it’s day, the TC-12 was reported to be unequaled in its ability to rip and push dirt. It was also claimed to be well suited to pushloading scrapers. Over the years, some operators have opined they didn’t live up to the performance hype. Not being experts on earthmoving, it’s difficult for us to comment but from research, we can say there is no gray area when it comes to opinions on the TC-12. Operators either loved it or hated it. The same went for maintenance people. The TC-12 was a complex unit, so proper maintenance was an important factor. Any complex piece of equipment will get mixed reviews on reliability, but most agree that a properly serviced TC-12 was reliable and durable, even if “properly serviced” meant “PITA” to those doing the service.

Look closely at the hood and stack levels in these images, plus the dash. The blade also angles with the oscillations. Riding this unique crawler gives you a different look at the work, not to mention being eight feet in the air.

The TC-12 was a challenge to transport, particularly back in the day. The TC-12 was gigantic but it was bigger than the other crawlers on the market…  wider, and heavier (30-35 tons without blade) and therefore a challenge to transport. Euclid solved that by making the TC-12 relatively easy to split into it’s two sections for transport. As larger equipment became more the norm, the TC-12 blended in more.

The first big upgrade came in 1958, with the TC-12-2. Among many other refinements, the 6-71s were unleashed to 227 maximum horsepower at 2100 rpm, delivering over 454 ponies together and 1,212 lbs-ft. By then, the market had begun responding to the TC-12 and bigger and more powerful crawlers entered the market to challenge the Euclid. For 1966, the TC-12 had other upgrades and its designation was changed to 82-80. By then, Euclid had other crawlers in the market. In 1968, GM was hit by an anti-trust suit and eventually had to split up the very successful Euclid Division. The truck division remained under that name and the crawlers and earthmovers moved under the new Terex brand name, “Ter” for Terra and “rex “ for King. Though no longer owned by GM, Terex remains in business, but Euclid does not.

The TC-12 mounted a pair of 6-71s appropriate to their era. In the latter era, they cranked out 227 hp each maximum, with rated power around 220.

The TC-12/82-80 remained in production until 1974 with a total of 901 units built of both types, about half and half divided between TC-12 and 82-80. By ‘74, simpler, single-engine dozers of equivalent or superior horsepower were on the market and the disadvantages of the complex and aging TC-12/82-80 design made it difficult to market.

Today, running TC-12/82-80 are few and far between. As with most big construction equipment, they are generally found in worn out condition and parts are difficult to obtain. Transportation costs for a collector often exceed to purchase price, so most TC-12s are found in the hands of construction company owners with the means to transport them.


1964 Euclid TC-12 
Engine: GM 6-71 (x2)
Displacement: 425 ci (each)
Bore & Stroke: 4.26 x 5 in.
Flywheel Power: 454 hp @ 2100 rpm (both)
Rated Torque: 1,212 lbs-ft @ 1400 (both)
Compression Ratio: 17:1
Transmission: Allison CRT-5531-1 (two)
Weight: 69,500 lbs. (operating)
LxWxH: 16 ft. 3 in. x 11 ft. 5 in. x 8 ft .8 in.
Fuel Capacity: 225 gal.
Tracks: 43 shoes, 27 in. width
Top Speed: 6.80 mph

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