mechanism, increased compression ratio, revised oil feeds, and two water pump replacements. Mark IV, a revised design providing a shaft drive for cooling fans. This replaced the troublesome chain drive. This version also changed the air compressor to run at a lower speed. Mark IVA, the power was increased to by increasing the governor limit to 1,700 rpm, and by fitting a new intake manifold and carburettor for the Cavalier tank. Mark V, a redesigned engine producing the same power as the Mark IVA but for use in the Centaur tank. It revised the oil distribution in the engine, but remained governed to the higher speed of 1,700 rpm. The engine was intended for the Cromwell tank, but the Liberty-based design was dropped in favour of the Rolls-Royce Meteor procured by the Tank Board. Those tanks fitted with Liberty were renamed Centaur, and production was split. Applications Aircraft The primary use of the Liberty was in aircraft. American-built versions of the Airco DH.4 Airco DH.9A Airco DH.10 Amiens Breguet 14 B2 L Caproni Ca.60 Curtiss H-16 Curtiss HS Curtiss NC Curtiss Carrier Pigeon Douglas C-1 Douglas DT Douglas O-2 Felixstowe F5L Fokker T.II Handley Page H.P.20 Witteman-Lewis XNBL The engine was also used in the RN-1 (Zodiac) blimp. Automobile Based on aircraft use the engine provided a good power-to-weight ratio. This made it ideal for use in land speed attempt vehicles. It was selected for two land speed record attempts. Babs, a single engined vehicle White Triplex, mounting three Liberty engines working in tandem Both attempts set new records. Both crashed during further attempts, resulting in the deaths of the drivers and a newsreel cameraman. Tank As early as 1917 the Liberty showed good potential for use in tanks as well as aircraft. The Anglo-American, or "Liberty", Mark VIII tank was designed in 1917–18. The American version used an adaptation of the Liberty V-12 engine of 300 hp (220 kW), designed to use cast iron cylinders rather than drawn steel ones. One hundred tanks were manufactured at the Rock Island Arsenal in 1919–20, too late for World War I. They were eventually sold to Canada for training in 1940, except for two that have been preserved. Inter-war, J. Walter Christie combined aircraft engines with new suspension design, producing a rapid and highly mobile tank. Using Christie's concept, Russian forces selected and copied the Liberty in the BT-2 & BT-5 Soviet