T55 Gun Motor Carriage

Development

The T55 Gun Motor Carriage has it origins in the experimental 8x8 desert vehicle designed by Cook Brothers. They started by building a chassis that joined two powered 4x4 bogies, each with its own engine, into an 8x8 vehicle. This unusual vehicle steered by pivoting the entire front bogie.

It became known as Cook’s Cozy Cabin because of its box-like shape. Little interest was shown in this all-terrain vehicle by the US Army, but Cook Brothers began work on an experimental tank destroyer.

This Cook Interceptor mounted a 3-inch gun. Two water-cooled Cadillac 8-cylinder engines were placed in the rear end of the vehicle and heavy-duty tires were fitted to cope with the extra weight. In an effort to gain a contract from the army, it was designed to be capable of fulfilling the functions of armored car, tank destroyer or armored personnel carrier. In August 1942 they received a contract for further development of the tank destroyer as the T55.

During tests in December 1942 the T55 was pitted against competing tank destroyer designs including the T48 57mm GMC half-track (later used by the Red Army as the SU-57). After testing, modifications were made to the vehicle resulting in the T55E1. This revised design was sent for further testing at the desert proving ground at Fort Irwin. Meanwhile, production of the T55 for the US Army started with the Allied Machinery Manufacturing Company.

Hypothetical Combat Service

The T55 3” Gun Motor Carriage was shipped to Tunisia in 1943 for field testing. Its eight-wheeled chassis and high ground clearance made it ideal for the open valleys and rocky mountainous terrain of Tunisia. Fighting alongside the M10 tank destroyer, this new vehicle proved itself and would soon be in action again in Italy.

In Flames Of War

The Cook Interceptor has turned out to be an excellent light tank destroyer. The M3 75mm GMC is equally small and light, but its gun is no match for the new 3-inch gun. This armament is the same as that in the much heavier M10 3” GMC, carried in a mount with far better mobility on road and in the open desert.

The T55 3” GMC is smaller and lighter than most tank destroyers, yet packs an extreme punch.

The Cook Interceptor wheeled tank destroyer is light and fast. Its high road speed makes it an ideal fit to tank destroyer doctrine as large numbers can quickly race to the site of any German armored breakthrough. In the open desert it is tactically more mobile than tracked tank destroyers.