Vickers Medium Mark I

The Vickers Medium Mark I was a British tank of the inter-war period that Vickers built from 1924. It grew out of the Vickers Light Tank prototypes of the early 1920s, whose unreliable hydraulic transmission led to a more conventional design that was renamed the Vickers Medium Tank Mark I in 1924. It had a low, flat suspension of five bogies on each side, an air-cooled 90 hp Armstrong Siddeley engine derived from an aircraft type, and a cylindrical turret with a three-pounder gun and four ball mountings for Hotchkiss machine guns. Its three-man turret let the commander concentrate on the battlefield, a feature no other maker repeated until the German Panzer III. Weighing about 11.7 long tons, it carried a crew of five behind riveted plating 6.25 mm thick and reached about 24 km/h. Thirty Mark I and fifty Mark IA tanks were built, they served in the Royal Tank Regiments until phased out from 1938, and one survives in South Africa.