The Steam Wheel Tank

by Tim Rigsby
 

 

The Steam Wheel Tank was the third heavy tank designed in the United States during the First World War. Its predecessors were the Holt Gas Electric, built in a joint venture by Hold and General Electric; the Steam Tank, built by the Army Corps of Engineers in conjunction with Stanley Steamer, famous for their Steam Cars.

The Steam Wheel Tank's design was laid down between late 1916 and early 1917.  One prototype was completed in February of 1918, and was put through a series of evaluation test between March and May of 1918, at Aberdeen Proving Ground, Aberdeen, Maryland.  Some reports of these tests state the Steam Wheel Tank became stuck after 50 ft, and thus ended it's evaluation.  This statement is not accurate.  The Steam Wheel Tank would get bogged down under it's enormous weight.  However, once enough pressure was build up in it's two kerosene fired boilers, it would pull itself free.

The Steam Wheel Tank was designed on the basis of the early "Big Wheel" Landships, put forth by Great Britain in 1915.  It also resembles the German "Treffas-Wagen" of 1917.  It had two large 8 ft by 3 ft wheels, located at the front on each side of the substructure.  They were made out of several sheets of pressed steel.  (They were not specially built wheels, they were used on Holt combines of that period).  At the rear, was a roller type wheel, (resembling a metal barrel ) used for steering.  To this a small steel skid plate (Tail ) was attached to aid in crossing a trench.

Power for this Mammoth was achieved by two Doble 2 cylinder 75 Hp steam engines.  Produced by Abner Doble, famous for his Doble Steam Cars, he produced in association with the General Electric Company in 1916.

The engines were mounted horizontally, each running it's own wheel, drive was taken from the pistons to driving and roller pinions, which engaged internal gears fixed to the front wheels.  Boilers were carried behind each engine; ventilation was achieved by using exhaust louvers in the rear of the vehicle, in addition to a fan driven by steam from the boilers, and a radiator which acted as a condenser for the engines.  Exhaust was through two small openings behind the main housing near the rear of the vehicle.

A crew of six was planned to man the Steam Wheel Tank.  Main armament was a 2.95" (75mm) mountain howitzer mounted in the front.  Additional armament was two Browning machine guns located in small ball mounts on both sides of the main fighting compartment.  The Steam Tank was 22 ft 3 in long, 10 ft 1 in wide and 9 ft 10 in high.  Armour was .23 to .63", weight was 17 tons.

The Steam Wheel Tank is known as many names:  the Hold 150 ton Field Monitor (so nicknamed as to hide its design feature from Germany and its allies );  the 3 Wheeled Steam Tank, the Holt Steam Tank;  but, its official name as designated by the Army is the Steam Wheel Tank.  Thus ends the mystery.