Perhaps no other track type tractor has quite the aura of mystery, is spoken of in reverent terms or has had so much misinformation published about it quite like the Euclid TC-12. By Richard Campbell
I have had quite a number of requests from readers to do a feature on this tractor, which was in fact featured in the very first historical article that I wrote for Contractor back in 1999.
As this article is now long out of print and in view of the high level of interest which still surrounds the machine I have decided to revisit the Euclid TC-12.
In the intervening years I have accumulated a great deal more information on Euclid’s “big twin”.
History
Prior to its acquisition by General Motors Corp in 1953, Euclid Road Machinery had begun planning a track type tractor suitable for use with its existing line of scrapers.
Unfortunately, research and development costs for a project such as this cost a great deal of money, even in the early 1950s, and Euclid simply did not have the financial resources to undertake anything other than studies.
General Motors also had designs on a very large track type tractor and once the ink had dried on the Euclid/GM merger things began to take shape very rapidly, the first prototype machine being put into testing at GM’s Milford testing grounds in July 1954 and the first series one production machines reaching customers in mid-1955.
With an output of 388 horsepower, these first tractors were far more powerful than anything the competition had to offer. By comparison, Caterpillar’s first D9, also released in 1955, only boasted 287 horsepower.
After only a year, Euclid made some modifications to the TC-12 which resulted in a change in designation to TC12-1
Apart from some cosmetic reworking the most important change was the engines output which was increased from 388 to 436 horsepower. Many of the TC-12-1 machines were delivered as high-powered scraper push tractors rather than bulldozers.
The definitive TC-12, in my opinion, was the model TC-12-2 introduced in 1958.
All of the machines imported into New Zealand were of this type, which featured a new, stronger front end, improved undercarriage and a horsepower boost to 454 horsepower.
Further changes
In 1966 Euclid changed the designation from TC-12-2 to 82-80 (mainly to keep it in with the rest of the ‘82’ family – the 82-30 and 82-40). Very little else about the machine was changed, however, an option was the addition of dual hydraulic lift cylinders for the blade in place of the cable control unit. This would eventually become standard equipment.
The name Terex replaced Euclid in 1968 with the division of the company following an anti-trust suit lodged against General Motors years earlier.
Total production of the Euclid TC-12/Terex 82-80 amounted to just under 1000 machines and the type was finally phased out in favour of the all new model Terex 82-50 in 1972.
All TC-12s and 82-80s were manufactured in the USA.
The TC-12-2 described
Two General Motors Detroit Diesel 6-71 diesels powered the Euclid TC-12. These were rated at 227 flywheel horsepower at 2100 rpm.
Connected to each engine were identical Allison 3-speed powershift transmissions. Unlike other track type tractors the TC-12 did not steer by clutch and brake but by individual control of the transmissions.
A turn to the left for example, could be made by putting the LH transmission into neutral and the RH transmission into 1st forward range. Counter rotational turns could also be made by putting one transmission into forward range and the other into reverse. The TC-12 was very manoeuvrable and responsive for such a big tractor, which in full operating trim weighed over 40 tons.
Unlike traditional track type tractors which have oscillating track frames and a centre equalizer bar, the TC-12 was able to cope with uneven ground conditions by virtue of the fact that the entire machine was split down the middle – a massive pin joined the back halves together while a roller and guide allowed the front of the machine to oscillate up and down over rough ground, thereby keeping both tracks on the ground.
Euclid employed a seven-roller track frame on the TC-12-2 with a 44 section track chain and a choice of track shoes starting at 24 inches wide.
The operator enjoyed a good view, despite the size of the machine and the two air cleaner caps placed directly in front of him. Two separate instrument panels (one on either frame half) gave vital operating information.
As to be expected of a machine designed in the 1950s, the seating was fairly basic.
I had the opportunity of operating a TC-12-2 in 1972 and the sheer brute power of the machine is one I will never forget – along with the sound!
Implements
Garwood provided the bulk of operating attachments for the TC-12. These ranged from front or rear mounted cable control units to the huge semi-U bulldozer blades employed on the majority of New Zealand operated machines.
