Renault UE Chenillette - Projects

Projects

One of the six Renault UE prototypes had a rubber track; in 1932 this line of development was taken further by rebuilding a vehicle into the Renault UE Neige ("snow") or Renault UE N. For better traction this type had a more robust suspension with a broader rubber track, powered by a stronger six-cylinder engine.

In the mid-thirties Chaubeyre produced the prototype of a smoke-laying vehicle, the generator using a thousand litres tank placed on a Renault UK trailer. The system was to be controlled from the commanders position of the main vehicle.

After the larger orders had been made in 1937, both AMX and the Renault design bureau, that had not been nationalised, tried to introduce further modifications to improve the production series. Several of these would indeed be incorporated into the UE 2 production run, but these were of a minor nature; there were however much more fundamental changes proposed, aimed at solving the structural suspension problems, that were the reason Berliet and Fouga still tried to obtain approval of their chenillette projects, even after a choice had been made for the Renault UE2: they hoped that eventually the Renault UE would be abandoned altogether. To be able to present immediate alternatives, should the occasion arise, AMX and Renault developed stronger suspension systems.

In February 1938 Renault presented stronger tracks and more resistant road wheels, with an improved device to keep the axles waterproof, to the Commission de Vincennes. These were tested from 12 February until 6 July and again from 21 September until 21 November.

In July 1938 a prototype of a lengthened chenillette was presented by Renault. It had a fourth bogie in the suspension to reduce track pressure and a third return wheel. To save weight and better dampen shocks the number of leaves in the leaf springs was reduced from six to three. The tracks were obviously longer too, with 156 instead of 131 links. The bin was also "longer" at 72 centimetres, but less "wide" with 123 cm. Internally a new centrifugal ventilator type was fitted. The total length increased to 335 cm, the weight to 3.67 metric tons. Trials took place between 13 July 1938 and 8 February 1939, during which the vehicle was again modified. The top speed without trailer transpired to be reduced to 32.7 km/h; unsurprisingly the trench crossing ability was improved to 160 cm. As the air outlets had been placed higher, the wading capacity was improved to 45 cm. However, the main purpose: ameliorating suspension reliability, was not really achieved. Tracks were still thrown, track guides bent, springs broke and entire bogies were sheared off, just as with the series model.

On 22 November 1938 AMX presented its new track fitted only to the right side of a trials vehicle so that direct comparisons could be made with the old track type. After 1500 kilometres the normal track was completely worn out and the AMX track was now fitted to a second vehicle; after testing had resumed on 9 January 1939 only after 3700 km on 21 March the new track was worn. The commission concluded that the new type was clearly superior in durability, but that this was caused by the use of chrome steel that made it 70% more expensive, too pricy for the French Army.

On 27 September 1939 AMX presented its new suspension system. It resembled that of the Renault R35, with two bogies, horizontal springs — be it here of the oil type — and five road wheels per side. The prototype also had a new Chausson radiator and more comfortable suspended crew seats. The new type however was not tested immediately; only after also Renault had presented another prototype, this time with seven road wheels — an extra wheel having been inserted in the space created by moving the bogie assembly twenty centimetres backward — both types were simultaneously compared between 7 and 23 February 1940. It was shown that the AMX suspension, though much sturdier, had a negative influence on the performance: speed and range fell with about 15%, mostly due to an incorrect weight distribution. The new seats, though clearly adding to crew comfort, were too high, preventing a soldier of normal length from closing the hood. However the new Renault suspension offered no clear advantages over the older model in terms of vibration level and crew fatigue, so both models were in the end rejected as possible modification projects of existing vehicles; AMX's type on 11 April 1940 was judged not to be acceptable for future production.