Char Moyen AMX 40

In March 1940, the Workshop of Issy-les-Moulineaux was studying a new medium tank of cavalry, the successor of the SOMUA S-35 and the S-40. The design was never built, due to the Fall of France in June 1940.

The AMX 40 Cavalry was designed as a medium tank, modelled along very futuristic lines. Its rounded hull offers only oblique surfaces; the undercarriage consists of four road wheels which was very modern for a 1940s tank. Its general hullform resembles that of postwar tanks. The tank had a cast steel body, 60mm front armor, side 50 to 30 mm and 40 mm to the rear. Length 5.30 m, width 2.45 m The chassis was composed of four-wheel drive twin 82cm in diameter protected with side shields. The two rear wheels are driven, which could allow the movement without the tracks. There were no return rollers; the drive sprocket is at the rear. Fuel tanks placed above the tracks were expected to help strengthen the lateral protection (the AMX-40 was to be diesel-fueled; unlike gasoline, diesel is not flammable at room temperature).

The AMX was expected to be powered by a diesel engine of 160 hp, low compared to the SOMUA's 190 hp and the S-40's 220 hp engines, for a vehicle with an estimated weight very close to the SOMUA (nearly 20 tonnes). However, the rotation system could save significant weight and provide good performance despite the power deficit. As mentioned earlier, the choice of diesel fuel improves safety.

The two-man turret casting has an ovoid shape reminiscent of the future Russian tanks of the T-54/T-55 family. Access was to be through a 60cm-diameter circular hatch on the back of the turret. The hatch follows the general shape of the turret, which has no protrusions except for two openings in the rangefinder. Visibility was to be provided by a panoramic periscope on top of the turret. No slot vision seems to have been planned. The solution is attractive in terms of protection, but the concentration of the tank's visibility into a single element would have adverse consequences in the event of damage to the periscope.

The main armament was expected to be an SA 35 47mm cannon, placed on the axis of the turret. Turret rotation was hydraulic, rather than hand-cranked. Breaking with the custom of one-man turrets, the AMX-40 was to have a dedicated gunner along with the commander in the turret. Both occupants sat on a swivelled strap with the turret gunner on the left and the commander on the right. In addition to the 47mm gun, the tank had a secondary armament of two 7.5 mm machine guns- one co-axial with the main gun for close defense, and one on a retractable swivel joint in a compartment behind the turret for anti-air defense. The tank could hold up to 156 rounds of 47mm, distributed in the periphery of the turret in rotating part lockers, to facilitate access to ammunition. The ammunition supply is higher by almost 50% than in the SOMUA.