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Military


Christie Tanks

J.Walter Christie was an innovative designer of tanks, engines and propulsion systems. Although his designs did not meet US Army specifications, other countries used his chassis patents. Despite inadequate funding, the Ordnance Department managed to develop several experimental light and medium tanks and tested one of Walter Christie's models by 1929. None of these tanks was accepted, usually because each of them exceeded standards set by other Army branches. For instance, several light tank models were rejected because they exceeded the 5-ton cargo capacity of the Transportation Corps trucks, and several medium tank designs were rejected because they exceeded the 15-ton bridge weight limit set by the engineers. Christie simply would not work with users to fulfill the military requirements but, instead, wanted the Army to fund the tanks that he wanted to build. Paton later worked closely with J. Walter Christie to improve the silhouette, suspension, power, and weapons of tanks.

In 1931, the Army purchased a group of tanks designed and built by the fabled J.Walter Christie. He was 66 years old at the time and famous for his pre-World War I front-drive racing cars; front-drive conversions to motorize horse-drawn fire engines; and World War I-era experimental tanks and self-propelled artillery designs.

The Christie tank embodied the ability to operate both on tracks and on large, solid-rubber-tired bogie wheels. The tracks were removable to permit operation on wheels over moderate terrain. Also featured was a suspension system of independently sprung wheels. Christie had developed his so-called “convertible tank,” which could run on tracks or on its own road wheels, in 1928, but he called this remarkable innovation the “Model 1940” because he felt it was years ahead of its time. This was not a complete tank because it lacked any armament and had no turret, but it was an astounding machine that by 1929 could run 45 mph on its tracks and 70 on its road wheels, although at these speeds the tank could not carry full equipment. This was possible because it only weighed 8.6 tons, and it was powered by a 338-horsepower Liberty aircraft engine.

Christie’s Wheeled Track Layer Corporation only built one Model 1940, but it did so well in tests the Army was determined to obtain a perfected version. The Army bought seven redesigned Christie tanks in 1931. To comply with federal law that limited tanks to the Infantry Branch, three were designated Infantry Medium Tanks T3 and the other four “Cavalry Combat Cars T1,” but they were all practically identical. They weighed 10.5 tons and had the 338-horsepower Liberty engine. They incorporated the Christie convertible principle and could run on either their road wheels or on tracks. They used Christie’s unique coil-spring suspension. The Army had to build their turrets because Christie did not design ordnance systems.

The Christies proved only marginally satisfactory. The tank’s complex dual road-wheel drive, steering-track system was troublesome. So was the chain final drive. With its suspension components, each Christie independent road wheel extended almost a foot out from either side of the hull, crowding the interior and making turret-mounting difficult. The track life, like that of most tanks of the period, was poor – only some 500 miles. And the Christies tended to throw tracks in violent maneuvering.

While the new components were undergoing test and development, the Army was also pursuing Christie’s designs. In 1933, Rock Island Arsenal redesigned the T1 Combat Car/T3 Medium. The Army believed Christie’s ideas had merit, but his designs were far from perfect. The Army decided to pursue several other lines of development besides Christie’s because of these problems. In 1934, the Army redesigned the Christie and had American-LaFrance – the fire-truck manufacturer – build one T3E4 Medium. While it was a vast improvement, it was not as good as other experimental tanks built about the same time.

The Army still thought the Christie convertible idea had merit, so in 1936 one last model was designed, the T6 Combat Car. However, due to the success of the other new designs, it was not built. One last Christie was built when, in 1936-1937, Rock Island Arsenal took an M1 Combat Car hull and mounted it on a Christie convertible suspension. This was the T7 Combat Car, but testing proved it inferior to the new production-model tanks. In 1939, the U.S. Army discarded the Christie design in favor of the much better tanks it had in production.

To the infantry and cavalry the Christie was the best answer to their need for a fast, lightweight tank, and they were enthusiastic about its convertibility. On the other hand, the Ordnance Department, while recognizing the usefulness of the Christie, was of the opinion that it was mechanically unreliable and that such dual-purpose equipment generally violated good engineering practice. The controversy over the advantages and drawbacks of Christie tanks raged for more than twenty years, with the convertible principle being abandoned in 1938. But the Christie ideas had great impact upon tank tactics and unit organization in many countries and, finally, upon the US Army as well.

Rock Island Arsenal used many of Christie’s ideas in its 1931 T2 Combat Car. This 8.5-ton machine used a novel power plant: a 165-horsepower Continental radial air-cooled aircraft engine. Although this tank was extensively rebuilt as the T2E1 in 1933, it was an unsuccessful vehicle. A similar T3 Combat was designed in 1932 but was never built because of the T2’s failure.



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Page last modified: 27-07-2016 18:53:33 ZULU