International-Harvester’s model TD-15 track type tractor was first introduced in 1958 and replaced its former model TD-14. By Richard Campbell.
The TD-14 had been an extremely successful and popular machine for International, and nearly 45,000 TD-14s were manufactured from 1939 when the model was first introduced, to 1958 when the last machine rolled off the production line, a remarkable achievement.
During its time in production, the type was manufactured in four different versions, each new version incorporating improvements over the previous model.
The TD-14 was especially popular with the US Armed Forces and it was used extensively in the Pacific, European and Korean theatres of operation, as a land clearer, earthmover, and also as a gun carriage!
By the mid-1950s however, the TD-14 was decidedly obsolete and International-Harvester embarked upon designing and building a new tractor to fill its now vacant 10-ton dozer category.
Replacing the TD-14 in 1958 was the new model TD-15.
The 10-ton bulldozer class was a hotly contested market spot and the TD-15 was up against some stiff competition, principally in the form of the Allis-Chalmers HD-11 (which had been launched 3 years earlier), and the newly introduced Caterpillar D6B.
Basic layout of the new TD-15 followed that of the former model TD-14 quite closely, especially the undercarriage, but featured an all-new engine, the 6-cylinder, naturally aspirated International D-554 diesel which produced 105 flywheel horsepower.
Manufactured in two versions, the first was the TD-15 150 series which weighed around 10 tons bare and had a 6-speed sliding gear manual transmission.
Around 3,500 of the TD-15 150 series were manufactured before it was replaced in 1961 by the TD-15 151 series which featured slightly more horsepower and weighed approximately 10.2 tons bare.
Using the same 6-speed sliding gear transmission as the former machine, the TD-15 151 series was only in production for one year (1961-1962) before it was replaced by the completely redesigned TD-15B.
About 2,000 TD-15 151 series machines were produced.
Just as an added bit of interest, the TD-15 was one of the first International track tractors to wear the new “Federal Hi-Way Yellow” paint, which replaced the former bright red that International were known for up until that time.
Ongoing issues with the TD-15 150 and 151 series undercarriage and final drives forced a major rethink by International-Harvester designers.
Their solution was a completely new track frame and undercarriage featuring newly developed planetary final drives and a revised, heavier equalizer bar assembly.
At the same time, an all-new engine was installed in the form of the 6-cylinder, turbocharged International DT-361 diesel which produced 120 flywheel horsepower.
Not content with all these changes, International also installed, for the first time in the TD-15 series, a power shift transmission with 4-speed ranges forward and reverse.
The TD-15B proved to be very successful for International-Harvester, users citing the excellent balance and visibility the machine provided for operators.
Over 10,000 International TD-15Bs were manufactured between 1963 and 1972 when the type was replaced by the TD-15C
By 1972, advances in technology meant that the TD-15B had reached the limit of its development potential and a further upgrade of the machine was required to keep the type competitive with its rivals.
This came in the form of the TD-15C, which was the last of the TD-15 series to be manufactured by International-Harvester itself in the USA.
First order of business was another new engine, this time in the form of the 6-cylinder, turbocharged, International DT-466 which produced 140 flywheel horsepower, and retaining the existing 4-speed powershift transmission.
This was a clever move by International as the DT-466 was used in several other of its machines, meaning that fleet users had a good source of parts commonality.
Some components of the undercarriage were further strengthened to provide more longevity with the ultimate result being that this particular version of the TD-15 was the heaviest so far at approximately 11 tons bare.
Like the previous TD-15B, the TD-15C was a very popular machine, remaining in production until 1984 with over 5,600 examples manufactured.
It is at this point that we will leave the story of the TD-15, as, although the type soldiered on for several more years and at least two more versions, it did so under a succession of new owners due to International-Harvester falling on very hard times.
For decades, International-Harvester relied on outside suppliers for bulldozer blades, cable controls, winches and towed ancillary equipment such as scrapers and rippers.
Prime subcontractors during this period were Bucyrus-Erie, Heil, Carco and to a lesser extent Buckeye (who later became part of Garwood).
International purchased Heil in December 1953, primarily to gain access to Heil’s motor scraper range which International then marketed as its own.
During the 1940s and early 1950s, supplying blades and other equipment for International was a dream arrangement for Bucyrus-Erie as International were shifting a lot of product, and a good percentage of it required attachments, which Bucyrus-Erie were only too happy to provide.
This all changed in 1956 when out of the blue, Bucyrus-Erie decided to focus their attentions more on crane and excavator production and development.
International-Harvester, not wanting to lose the prime source of attachments for its track type tractors, wasted no time in cementing a purchase agreement with Bucyrus-Erie for its machinery attachments division, and began marketing these as its own branded items in short order.
For the model collector.
There have been at least four 1:50 scale models of the International TD-15C version produced to date, all by American diecast maker First Gear, and all in different configurations.
These are excellent little models and well detailed for their size, however, finding one can be a little problematic as First Gear appears to have discontinued the line entirely.
Good luck finding one on Ebay.
Brief specifications – International TD-15C
Engine: International DT-466, 6-cylinder, turbocharged diesel rated at 140 flywheel horsepower at 2500 rpm
Transmission: 4-speed forward and reverse, countershaft powershift transmission
Top Speed: 6 mph
Steering: Planetary type with multi-disc brakes. Constant power to tracks.
Final Drive: Double reduction planetary final drives
Track Gauge: 74”
Track Shoe: 18” single grouser standard, other options available
Track Chain: 39-section, sealed
Rollers: 6 per side with 2 carrier rollers per side
Weight: 14 tons with hydraulic system, S-blade and tilt cylinder