AMX 40

France (1940)
Cavalry Tank – None Built

The Char de Bataille AMX 40 modèle 1940, more famously known as simply the AMX 40, is one of the numerous French tank designs which were created in the 1930s and 1940s, but never went past the drawing board, either due to not garnering enough interest, or the unfortunate interruption caused by France’s military woes in 1940. AMX’s cavalry tank project is arguably one of the most famous of those designs, largely due to its appearance and distinct look in a popular video game.

Christie and Cruiser influences

One of the most important trends in worldwide 1930s tank design was the Christie suspension. This system made use of very large road wheels which moved vertically on bell cranks. One of its main advantages was that it enabled very high speeds in tanks and potentially allowed for convertible drive, which allowed the tracks to be removed. Christie-type suspensions were experimented on by a variety of designers in the 1930s, the British and Soviets being the most extensive users of the system with tanks such as the BT-2, BT-5, BT-7, Cruiser A13 Mark I and Mark II.

France was not one of the first countries to experiment with Christie designs, mostly due to French tank designers preferring suspensions which enabled greater cross-road capacities, even at the expense of speed. Nonetheless, Christie suspensions were considered to an extent. A Christie chassis is known to have been trialed in front of the Commission de Vincennes in March of 1938. Later, in April of 1939, there were some exchanges between the French and British technical services, including on the subjects of tanks. Some of the more modern British tanks of the time were the A13 Mark I and Mark II cruisers. Those designs, using Christie-type suspensions, offered faster maximum speeds than French cavalry tanks designs, with 48 km/h. The only French tracked vehicles that offered a better maximum speed at the time were the AMR 33 or AMR 35 reconnaissance light tanks/tracked armored cars, which could only bring to bear a 7.5 mm or 13.2 mm machine gun in a one-man turret, while the A13s featured the potent 2-Pounder 40 mm anti-tank gun in a 3-man turret. Those designs had some considerable influence on Joseph Molinié, chief engineer of the fairly young AMX design bureau, a state-owned tank manufacturer born out of the nationalization of Renault’s tank producing services in 1936.

The AMX 40 project

The influence of the Christie and Cruiser designs pushed the AMX design bureau to make plans for a vehicle that combined these features with some more commonly found in French, but not British designs, such as, notably, a cast construction. The result was the AMX 40, a design presented on 4th March 1940, which could be summed up as the meeting between the British Cruiser tank concept and French industrial techniques. AMX hoped the proposal could potentially become a replacement for the S35/S40 cavalry tanks manufactured by Somua & cie, a subsidiary of Schneider.

Basic characteristics

The AMX 40 proposal was a 16-ton cavalry tank, which featured a 3-man crew, a commander/gunner and a loader in a 2-man ovoid turret, and a driver in a centrally placed driving post. The vehicle would have had a length of 5.33 meters, a width of 2.45 m, and a height of 2.37 m (1.58 m without the turret). The hull, without the suspension, was 2.03 m wide. The vehicle made use of cast construction and featured, as main armament, the 47 mm SA 35 anti-tank gun, featured in a large variety of French tanks of the late 30s, such as the Somua S35 and S40, the B1 Bis, or the second production run of the Renault D2.

Hull design

The AMX 40’s hull used cast construction. In comparison to most other tanks of the era, it had a much rounder shape, which was interrupted by the central driving post. This post featured a large openable hatch, which could be opened to provide vision when outside of combat. In combat, three episcopes, one in the center and one on each side, would provide vision for the driver. To his right was the ammunition stowage for 7.5 mm drum magazines, and to his left batteries and storage.

The tank would have been steered via a steering wheel. One of the various unusual features of the AMX 40 would have been a Robin-Van Roggen continuously variable transmission, an automatic transmission system without individual gears. This transmission was installed on the rear left of the hull, behind the engine. The AMX 40 was, as designed, powered by a 4-cylinder Diesel Aster engine which produced 160 hp at 2,000 rounds per minute, though a larger and more powerful Aster Diesel which had 6-cylinders and would produce 220 hp was considered to replace this first engine. This engine was also installed on the hull’s left-side, with the air filter and radiator on its right; to the right of the transmission, was the tank for engine oil. The exhaust was on the transmission’s left.

The diesel fuel tanks of the vehicle were installed in the hull sides. As the diesel fuel used by the vehicle was less flammable than ordinary fuel, they were thought of as potentially increasing the tank’s protection to a small extent. The armor of the AMX 40’s hull was 60 mm thick at the front, 50 to 30 mm on the sides with additional 15 mm sponsons, and 40 mm at the rear. The use of cast and heavily sloped armor meant that, unless projectiles hit the driver’s post, they would strike the vehicle on sloped armor, heavily increasing the armor’s effectiveness.

In front of the engine compartment but behind the turret, the AMX 40 featured a radio, of which the exact model is unknown. Another very odd feature, the hull-mounted anti-aircraft machine-gun, was mounted in this area of the tank.

Suspension

The AMX 40 project featured a model of suspension based on the Christie design. At the rear of the suspension was the drive sprocket, and at the front, an idler wheel. The suspension featured four large road wheels per side, which had a diameter of 82 cm. Considering their size, there was no need for return rollers.

As with several Christie designs, the AMX 40 was meant to be able to continue operating in the event of a broken track. To this extent, the first two road wheels were driving wheels which could be rotated to an extent, while the two rear wheels were motor wheels.

Most of the suspension was protected by 15 mm-thick side skirts, which would only have left the bottom of the roadwheel, the front of the tender wheel and the rear of the drive sprocket visible.

As a cavalry/cruiser tank, the AMX 40 was planned to reach quite high speeds, with 45 to 50 km/h on-road being the goal. However, with a horsepower of just 10 hp/t with the first Aster diesel engine, whether or not such a maximum speed could be reached is quite questionable.

Turret design

Like the hull, the turret of the AMX 40 had a cast construction. It had an egg-like shape, with the rounded gun mantlet sticking out at the front. This turret was meant to house two men. To the left of the gun, the gunner (who also assumed the role of commander), and to the right, the loader. They were sitting on a strap that rotated with the turret. Though a two-men turret was a quite commendable feature for French designs, which massively used ergonomically catastrophic one-man turrets in the 1930s, the small diameter of the turret ring, with just 90 cm, would likely have made this turret quite cramped.

The turret featured a hydraulic rotation system commanded by a handle in the turret. The tank for the liquid used for this system was located in the rounded top of the turret. There was a single vision source for the turret, a panoramic telescope installed on top of the turret. The two openings on the side of the turret were for the tank’s optical rangefinder. The right opening housed an optical sight which would have allowed for a field of view of 50°, whereas the left opening housed a telemetric sight which would have allowed for a field of view of 15°.

The turret featured a 60 cm wide round hatch on the rear, which could serve to evacuate the vehicle. It may have also allowed the commander to sit on it when opened, and look out of the tank. The turret was protected by 60 mm of armor all around and, as with the hull, its cast construction made it heavily angled, which could have further increased its effective armor.

Armament and ammunition stowage

The main armament of the AMX 40 was a 47 mm SA 35 anti-tank tank installed centrally in the turret, which had a maximum depression of -14° and elevation of +18°.

The standard issue shells for the 47 mm SA 35 were the Obus de rupture modèle 1935, and the obus explosif modèle 1932, both 47×193 mmR.

The Obus de Rupture modèle 1935 was an armor-piercing capped (APC) shell. It weighed 1.62 kg, and had a muzzle velocity of 660 m/s. German testing of the shell showed an armor penetration of 40 mm at an incidence of 30° and a range of 400 m. This was far superior to the penetration capacities of the SA 34.

The Obus explosif modèle 1932 was a high-explosive (HE) shell. It weighed 1.41 kg, including 142 grams of explosives, and was fired at a muzzle velocity of 590 m/s.

The AMX 40 also featured a coaxial machine gun, which, as with the vast majority of French tanks of the era, was a MAC 31E machine gun. It used the standard 7.5×54 mm French cartridge. The MAC31 Type E had a weight of 11.18 kg empty and 18.48 kg with a fully loaded magazine, those being 150-rounds drums. The machine gun was gas-fed and had a maximum cyclic rate of fire of 750 rounds per minute. It had a muzzle velocity of 775 m/s.

One of the vehicle’s odder features, a retractable anti-aircraft 7.5 mm machine gun, most likely the MAC 31E, though the MAC 34 aircraft machine gun is sometimes mentioned instead, was also placed behind the turret. This machine gun would emerge behind the turret, and be used against aircraft to the rear of the vehicle. Though it did feature an anti-air sight, the usefulness of this machine gun in practice is very much questionable: its firing arc was to the rear only, and to operate it, one of the three crewmen would have to leave his post. Though an anti-aircraft mounted on the top of the turret would most likely have been far more effective, with no hatch on top of the turret, this would not have been practical either.

The AMX 40 had two circular racks for 36 rounds each on each side of the hull, behind the turret and in front of the radio and anti-aircraft machine gun. Another ammunition rack for 30 rounds was located just behind the driver’s seat and could be collapsed for easier access from the turret. Two small racks of 10 shells each were located in the hull, in front of the turret, and to the sides of the collapsing rack. This gave the vehicle a total 47 mm ammunition stowage of 122 rounds, none of which were stored within the turret itself.

As for 7.5 mm ammunition stowage, 4 150-round drum magazines were present in the turret, on the side, and to the front of it. In the hull, to the right of the driver, was a rotating chain mechanism that could contain 30 drum magazines. This chain would be rotated as magazines were taken from it, in theory allowing for constant access to new magazines, though the need for such a system was questionable. With 34 150-rounds drum magazines carried, the AMX 40 had 5,100 7.5 mm cartridges at its disposal.

A project which did not go anywhere

The AMX 40 is often said to have been planned as the replacement to the Somua S35 and S40 tanks. This statement ought to be tempered to an extent. It is quite clear that, with the design of a cavalry tank such as the AMX 40, the state-owned tank manufacturer wanted to compete with the privately-owned Somua to provide a cavalry tank for the French Army. However, the AMX 40 was presented in March of 1940, mere months before the fall of France, and by June of 1940, it appears the project was still far from being considered for prototype production. The fall of France would result in a large number of projects being canceled, though the design of new French armored vehicles would continue both openly and covertly, with vehicles such as the Panhard 178 CDM, CDM Armored Car or SARL 42 on the covert side, or improvements of the Somua S40 on the more official side.

Errors with the AMX 40 in World of Tanks

As it is, the AMX 40 was a short-lived cavalry tank project which, while it did include some unusual and interesting features, did not go anywhere near even prototype production, and as such would most likely have remained fairly ignored. This, however, changed drastically when Wargaming’s popular online game World of Tanks (WoT) added French tanks as part of its 7.1 update in January of 2012, with the selection of vehicles added including the obscure AMX cavalry tank project.

The AMX 40, as it is featured in WoT, is in several ways inaccurate. When first unlocked, while the vehicle features its original turret, it is armed with the 47 mm SA 34, a much less potent predecessor to the SA 35, which was mounted in several tanks of the mid-1930s, such as the B1 or first series D2, but was long out of consideration for any new designs years before 1940. The historically accurate 47 mm SA 35 can then be researched. In-game, the armament of the AMX 40 can be upgraded even further though. The original ovoid turret design can be replaced by a new turret that the game calls the “Renault Balland”. This is, in fact, the turret design of the Renault G1R, a medium tank project which reached the mock-up stage, and of which a prototype was to be assembled in the summer of 1940. This turret, however, was a very particular design. The gun mount’s weight was laid on the hull itself, with the mount going to the bottom of the hull, its weight not laying on the turret itself. It is unlikely such an unusual turret design could have been fitted on the AMX 40 without extensive modifications. This is even more noticeable due to the fact that this turret is simply too large for the AMX 40 hull, with some considerable overhang on the side of the driver compartment. When first unlocked, this turret mounts the 47 mm SA 35, though it can later be armed with a 75 mm gun called the “SA 32”. While the turret does follow the historical path of the G1R turret, with evolved from a 47 mm to a 75 mm main armament (as well as from a two-machine gun to a one machine gun commander cupola), the use of the “SA 32” designation for a 75 mm gun is questionable.

Among other inaccuracies present in WoT’s AMX 40 is the engine. The Aster engine the vehicle starts with produces 150 hp, instead of 160 hp. While a historical option for an engine upgrade, the only historically accurate potential upgrade for the AMX 40, exists in the form of the 220 hp Aster engine, Wargaming instead went with a 190 hp “Somua LM” engine. In-game, the AMX 40’s poor engine power translates to very poor mobility, with the tank struggling to reach 20 km/h on even ground. Though the 45/50 km/h maximum speed hoped by its designer was certainly optimistic, this remains a surprisingly low speed for a tank meant for cavalry duties.

Conclusion – an obscure project rendered famous by gaming

The AMX 40 is, as it was historically, a fairly obscure project, which only existed for three months, and as such never really went far at all in its development. It did feature a considerable number of odd and sometimes innovative features. Its cast construction took the general lack of hard angles and use of sloped surfaces on French vehicles to a new level, and its two-man turret was quite significant for a French cavalry tank below 20 tons, though by the time the tank would realistically have entered service if adopted, in 1941 or even 1942, its armament would most likely have been quite lackluster, and the hull’s ability to mount a larger turret was doubtful due to its design.

The vehicle entered a second life due to its introduction in the popular video game WoT, being generally laughed at, though at the same time viewed with affection by the community. This newly-found relevance of the vehicle may also make it confusing, as another project which went much further bears the name of AMX-40 – a major evolution of the AMX-30 MBT offered as an export tank in the 1980s, mounting a 120 mm gun and many system which are now featured in the Leclerc. Though a prototype of the modern AMX-40 remains in Saumur, all that has survived of the WW2 project are the plans.

AMX 40 specifications
Dimensions (l x w x h)	5.33 x 2.44 x 2.37 m
Hull width without suspension	2.03 m
Weight	16,000kg (estimated)
Engine	Aster 4-cylinders diesel producing 160hp at 2,000 rpm; Aster 6-cylinders diesel producing 220 hp considered.
Maximum speed	45 to 50 km/h (estimated)
Power-to-weight ratio (in hp/ton)	10 (Aster 160hp)
Transmission	Robin Van Roggen continuously variable transmission
Fuel Tanks	400 liters
Average hourly fuel consumption	17 liters per hour
Range	< 500km
Suspension	Christie
Crew	3 men (Commander/gunner, loader, driver )
Armament	47 mm SA 35 main gun (122 rounds), coaxial MAC 31E machine gun, hull-mounted MAC 31E or MAC 34 anti-aircraft machine gun (5,100 7.5 mm rounds)
Optics	Panoramic telescope, telemetric & optical sight (turret); episcopes (hull)
Armor	60 mm on the turret & hull front, 50 to 30 + 15 mm on the hull sides, 40 mm on the hull rear

Sources

Tous les blindés de l’armée Française 1914-1940, Histoire & Collection editions, p 118
Char-français
Plans from the Archives de l’Armement via mémoire des hommes