One of the most creative minds of his era, and a prolific inventor/designer, Robert LeTourneau first came up with the idea of the Tournatractor in 1946 as a more flexible way of speeding up bulldozer jobs and lowering cost per yard. By Richard Campbell.
Constantly thinking of new ways to improve the earthmoving cycle, LeTourneau figured that a rubber tyred bulldozer could be moved around the jobsite faster, be driven by road (where legal) between job sites without having to wait for a transporter, and give the operator a better ride.
Following his success with the Tournapull, the world’s first self-propelled motor scraper, LeTourneau began experimenting with his rubber tyred dozer concept following World War II.
Conventional track type tractors of the day were good for a top speed of around seven miles per hour but often had difficulty in keeping up with the new high speed scrapers.
A rubber tyred dozer offered a top speed of some 15 miles per hour, more than enough to cope with the new scrapers, this also meant that they could quickly travel to where they were needed.
If the jobs were separated by public roads, then it was no problem for the Tournadozer to travel there under its own power.
Of course, there is no perfect tractor, and the Tournadozer was not suitable for all jobs, particularly those where high flotation was a requirement.
The original production run of Tournatractors were supplied on narrow base tyres and this caused some problems in the field before LeTourneau reverted to a wider base tyre.
Interestingly, one of the trickier underfoot conditions that the Tournadozer handled very well was sand, and sand is a material that wore conventional track-type tractor tracks out very fast.
Following some in-house testing and several prototypes being trialled on select customer jobs, the first ‘production’ Model C Tournadozer was introduced in September 1946.
From its introduction, until it was finally discontinued in 1972, development of the type was continuous and saw many alterations and tweaks being made to keep the machine current and viable. This was especially because opposition manufacturers saw the unique benefits that a rubber tyred bulldozer could offer and began to offer their own versions of this type of machine, imitation they say, is the kindest form of flattery!
(There were also Model A and Model B Tournatractors, but these fall outside the scope of this article).
One of the very early proponents of the Model C Tournatractor was the U.S. Military which saw the obvious potential and mobility that a machine of this type could offer; many examples were sold to the Army, Air Force and Marines where they were utilised worldwide.
Overseas customers were not slow in realising the potential of the Tournatractor either, and export sales of machines to South America, India and North Africa were very strong.
In 1953, Westinghouse Air Brake bought out LeTourneau; the company becoming LeTourneau-Westinghouse, the Model C was carried over in production as the LeTourneau-Westinghouse Model C Tournatractor.
The final version of the machine was the Model CH Tournatractor, which featured a hydraulically operated blade (all previous models having cable operated blades).
Robert LeTourneau must have shuddered at this version as he had a known aversion to hydraulic systems.
The Model C Tournatractor in detail
Like most of LeTourneau’s early designs, the Tournatractor was simplicity itself.
The entire chassis was a rectangular, welded, metal tub into (or onto) which all the necessary components were inserted or attached.
The underside of the ‘tub’ was completely smooth and, therefore, safe from rocks and other projections.
Initial production machines were powered by a six-cylinder Buda 6-DC844 diesel engine.
However, subsequent machines could have either a six-cylinder General Motors 6-71 diesel or a six-cylinder Cummins HBIS600 diesel, the predominant powerplant being the GM 6-71.
LeTourneau designed and built the four-speed Tournamatic powershift transmission with a torque converter that was bolted directly to the engine’s flywheel giving the machine a top speed of approximately 17 miles per hour in top gear.
Initially this transmission gave a fair bit of trouble as it had air operated clutch packs that were prone to leakage.
This usually resulted in more than one gear being selected at once with the inevitable catastrophic consequences.
Final drives were bull gear and pinion, totally encased in box section side frames which kept everything in alignment.
The Tournatractor steered much like todays skid-steer loaders; utilising a set of multiple plate disc brakes on each wheel with a central steering clutch to effect gradual or spot turns – it was effectively able to turn in its own length.
Sitting very close to the front of the machine, the operator had an excellent view of the blade and work area.
LeTourneau trialled a system of push button switches for transmission shifting on early machines but quickly changed to a manual system when reliability of the switches was found to be very wanting.
A wide range of attachments could be hung off the Tournatractor to equip it for work.
The standard dozer blade was a 12 foot wide, electrically activated, cable operated type and a similarly sized angle blade could also be fitted.
These were reeved very cleverly so that the electrically operated winch could apply a measure of downforce, if needed, for penetration.
Scraper push plates, a rear mounted double drum cable control, a towing winch, snow plow, rail wagon coupler, tree pusher and a scrub rake were all advertised as available options to equip the Tournatractor for its intended tasks.
An enclosed cab for the operator was also offered as an option.
Ready for work, a Model C Tournatractor weighed approximately 17 tons.
At least eight Tournatractors were imported into New Zealand by (then) franchise holders of the time, Earlo Tractor Co and ,latterly, Frederic W Smith Ltd.
Two of these worked on the construction of Wellington Airport in 1956, but complete records of owners no longer exist and even photos of them working in New Zealand are rare.
For the model collector
There are several models in 1:50 scale of 1950s-era Model C Tournatractors produced by EMD Models (and available through Buffalo Road Imports, USA).
While not cheap models, they are accurate and well made with realistic tyres for the time period.
Back in the good ‘ol 1950s, there was also an approx. 1:20 scale tinplate model of the Model C Tournatractor (produced as a child’s toy) by Nylint in the USA and Boomaroo in Australia.
These are actually pretty good representations of the real thing but can be a little expensive if you find one.