Tanks in World War I
The continued need for four men to drive the tank was solved with the Mark V which used Wilson's epicyclic gearing in 1918. Also in 1918 the French produced the Renault FT, the result of a co-operation between Estienne and Louis Renault. As mentioned before, it had the innovative turret position, and was operated by two men. At just 8 tons it was half the weight of the Medium A "Whippet" but the version with the cannon had more firepower. It was conceived for mass production, and the FT became the most produced tank of World War I by a wide margin, with over 3,000 delivered to the French Army. Large numbers were used by the Americans and several were also lent to the British.
Armoured fighting vehicle
The term "super-heavy tank" has been used to describe armoured fighting vehicles of extreme size, generally over 75 tonnes. Programs have been initiated on several occasions with the aim of creating an invincible siegeworks/breakthrough vehicle for penetrating enemy formations and fortifications without fear of being destroyed in combat. Examples were designed in World War I and World War II (such as the Panzer VIII Maus), along with a few in the Cold War. However, few working prototypes were built and there are no clear evidence any of these vehicles saw combat, as their immense size would have made most designs impractical.
A flame tank is an otherwise-standard tank equipped with a flamethrower, most commonly used to supplement combined arms attacks against fortifications, confined spaces, or other obstacles. The type only reached significant use in the Second World War, during which the United States, Soviet Union, Germany, Italy, Japan and the United Kingdom (including members of the British Commonwealth) all produced flamethrower-equipped tanks. Usually, the flame projector replaced one of the tank's machineguns, however, some flame projectors replaced the tank's main gun. Fuel for the flame weapon was generally carried inside the tank, although a few designs mounted the fuel externally, such as the armoured trailer used on the Churchill Crocodile.