Renault R 40

The biggest weakness of the Renault 35 was its chassis. The rubber hoops of the running wheels wore out quickly and the weight distribution of the tank was not equal on all wheels. This caused very poor driving characteristics in unpaved terrain. Therefore, several proposals were made to modify the chassis of this tank.

Lorraine's proposal copied the chassis of the Lorraine 37L artillery tractor, but modifying the chassis would weigh too much. Another unacceptable thing was that 118 new holes would be required in the hull to mount the chassis components. It was not considered that the advantages of such a chassis would produce an acceptable effect, so this proposal was rejected.

AMX's design was strongly reminiscent of the Renault D2 chassis, where the wheels were mounted in vertical hinges. The chassis was based on the "Holt" concept used by, for example, the B 1. The chassis consisted of 12 double rolling wheels. This solution allowed an efficient distribution of weight to the individual running wheels.
The company itself Renault had up to three designs. The first proposal was to double the number of running wheels (5 vs. 10). Each wheel was replaced in position by a pair of smaller wheels. The horizontal suspension remained identical. However, the result of the tests revealed that this solution was even worse than the original one. The second design consisted of mounting nine running wheels in vertical suspensions. It was similar to the AMX design, but the suspension was not external but internal. Chassis replacement was not complicated and could be done by the regimental field workshops, but the weight of the modifications was up to 2 tons. This weighed heavily and Renault chose the AMX solution. A third proposal by Renault should be mentioned, which was to extend the conventional chassis by one running wheel. It was the same running wheel as the first running wheel but mounted the other way around. This sixth wheel took the position of the tension wheel and this was mounted in a sort of extended body. This solution increased the weight of the tank by 700 kilograms.

The first comparative tests of the original Renault 35 with the AMX design and the extended version by Renault took place on 19 May 1938. The clear winner in terms of stability, hill climbing, obstacle clearance and track clearance was the AMX design. However, the top speed was not increased and the range was reduced. The reason was the increase in the weight of the tank. After a third series of tests on 16 February 1939, the AMX chassis was declared the winner and serial production was ordered. Originally the modified tank was to be called "Char léger modèle 1935 R modifé 1939" (later renamed Renault R 40). A modified version was to be produced after the 1500 was produced. R 35R 35. The assumption was that it would be produced in 2/1940, but due to the slow implementation of the changes in the production process, production was delayed by a month and around 40 more tanks were produced in the old Renault 35 form. The first identified production R 40 tank was the vehicle with registration number 51549, which was the 1549th machine (theoretically, the first R 40 could have had registration number 51541).
The total number of R 40 tanks produced is not known exactly. It ranges between 120 and 140 units. The last machine delivered on 15.6.1940 to the main depot in Gien was a tank of registration number "51649". However, there is evidence of continued production at the Renault factory in Saint Etienne, where the last known registration number was "51658". This would bring the number of tanks produced closer to the figure of 120. However, some time ago a photograph was found showing a tank with registration number "51669". There is also a photo in the source with the highest documented number "51670". This would bring the number of tanks produced closer to the number 130. Francois Vauvillier lists a total of 155 tanks produced.

Francois Vauvillier - The encyclopedia of French tanks and armoured vehicles 1914-1940, Histoire & Collections, published in 2014, ISBN: 978-2-35250-322-4
Pascal Danjou - Renault R35/R40, Tracstory No.4, Editions du Barbotin, published in 2005, ISBN: 2-9520988-3-2
Ivo Pejčoch - Obrněná technika 7, France 1919-1945, published by Ares, Prague 2007, ISBN 978-80-86158-47-1

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Tank crew repairing the engine cover

R-40 on a heavy transporter

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