| abstract | - The International T-9 and TD-9 replaced the unstyled McCormick-Deering T-35 and TD-35. The new models continued the styling theme introduced in 1938 on the big TD-18 crawler. All of the new International crawlers had engine side screens with horizontal silver stripes, matching three silver grille bars dividing sections of red cross bars. The T-9 looked almost identical to the T-6, except scaled up. The main visual clue from a distance is the presence of two top track idlers on the T-9/TD-9 vs. one on the T-6/TD-6. Instead of the 6-cylinder gasoline engine of the T-35, the T-9 used a new 335 ci 4-cylinder gasoline engine, governed at 1400 rpm, with a 5-speed transmission. This engine and transmission were shared by the McCormick-Deering W-9/WD-9 series wheel tractors. In 1940 the T-9 competed with the Caterpillar R-4 and Cletrac BG-6 but was more powerful than both. International dropped the T-9 in 1956. The TD-9 used a diesel version of the 335 ci 4-cylinder of the T-9 instead of the 414 ci diesel of the TD-35. When it introduced the TD-9, International was trying to compete with the Caterpillar D-4 and so it designed a very similar tractor. Both tractors were the same size and powered by 4-cylinder diesel engines running at 1,400 rpm with 5-speed transmissions. Caterpillar used its pony motor starting system while the International started on gasoline and then switched to diesel. The basic International was crank started with an electric starter optional. In 1940 the TD-9 had a slightly larger engine than the D-4, 335 ci vs. 312 ci, and developed slightly more power, 44 vs. 40 belt hp. The only other tractor in this class was the Cletrac BD-6, which developed 46 belt hp from a 298 ci 6-cylinder Hercules diesel running at 1,400 rpm. The Cletrac had only a 3-speed transmission. In 1947 Allis-Chalmers brought out its new HD-5, the most powerful tractor to date in this class with 48 belt hp. Caterpillar increased the engine size of the D-4 to 350 ci, boosting it to 48 belt hp also. International responded in 1951 with a small upgrade to the TD-9 that developed 47 belt hp. About the same time the tractor lost its engine side screens and silver bars in the grille. In 1955 Caterpillar went to 59 hp, Oliver to 57 hp, and Allis-Chalmers to 61 hp. Clearly the TD-9 was falling behind its competition so, in 1956, International brought out the revised International TD-9 Series 91 .
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