Renault UE Chenillette - Development of The Renault UE2

Development of The Renault UE2

From 1935, in reaction to the German rearmament, the French Infantry embarked on a major expansion and modernisation programme. Part of this was the project to replace the Chenillette Modèle 31 with an improved type, which however should remain within the weight limit of the earlier vehicle or 2.6 metric tons. Interest from the side of the French industry was high and during 1937 five companies proposed prototypes: Lorraine, Hotchkiss, Fouga, Berliet and Renault.

Lorraine de Dietrich, a company specialised in locomotive construction, presented a tractor and trailer to the Commission de Vincennes on 23 April 1937. The prototype was tested between 28 April and 10 June. Though at four tons heavier than specified, the type is approved by the commission on 8 July, with the period of testing extended to 23 August. Compared to the Modèle 31, the Lorraine chenillette is much more a dedicated supply vehicle, the larger size of which allows for a superior carrying capacity, crew comfort and range, while its suspension with two bogies and four large road wheels ensures a good tactical mobility. On 8 September the commission concludes that there are no objections to series production; already the prototype had on 25 August been presented to the Commission de l'Infanterie at Mourmelon for tactical evaluation. Clearly the Infantry favoured this type but eventually it was decided to use all production capacity for the longer Lorraine 37L, as there was a lack of heavier movers; a first order of a hundred made early 1939 was in September changed into one for the other type.

On 3 November 1937 Hotchkiss presented the prototype of a tractor; on 10 December of a trailer. On both elements however the manufacturer had not done any testing, the vehicles having been transported to Vincennes as soon as they were finished. Therefore the commission delayed its trials until 27 December to allow Hotchkiss to make final adjustments on the base area. The tractor was tested until 10 February 1938. The type closely resembled the general outline of the Renault UE. The main difference was the presence of two bins instead of one, able to tilt sideways, positioned over the back of the mudguards. This doubled the carrying capacity. Instead of the small hoods, two very large armoured covers, retractable to the back, served as both entrance hatch and visor. The engine, differential and steering system were judged to be acceptable. The suspension system however was considered to be too weak, not having been reinforced to match the larger cargo mass to avoid surpassing the specified total weight. It consisted of two bogies, each with two small road wheels, sprung by narrow horizontal coil springs. A large tension wheel trailed on the ground, which lowered ground pressure to compensate for the larger weight of the bins but also increased track resistance and vibration. The cross-country speed was just 15 km/h. As even during testing when fully loaded entire bogies collapsed, the prototype was rejected.

The Fouga aircraft company submitted a prototype tractor and trailer on 2 February 1939. It was tested until 8 May. This vehicle also closely resembled the Renault UE, but had a higher roof, making hoods unnecessary and enlarging the cargo space. Its suspension had two bogies per side with each two road wheels, sprung by leaf springs. The type, its submission too late because a choice had already been made for a rivalling type, was rejected because its mechanical parts were not easily accessible and the vibration level was too high.

Berliet obtained an order for a prototype on 4 December 1936. A tractor and trailer were however only presented to the Commission de Vincennes on 6 March 1939, testing starting immediately. The type again resembled the Renault UE but was somewhat higher. It had three bogies per side with two road wheels each, sprung by horizontal coil springs. The weight was 3.05 metric tons, its stop speed 36 km/h, the range 143 kilometres. The first report of the commission was favourable and trials are resumed on 24 April, lasting till 20 May. It transpired that the tractor could attain a top speed of 30 km/h even when pulling the trailer. The commission concluded on 8 June that the Berliet chenillette was superior to the Renault UE in speed, range and mechanical reliability and saw no objection against taking it into production. This however was eventually rejected by the Army in order to concentrate all production facilities into a single type, which had already replaced the UE: the UE 2.

Renault had been further developing the Renault UE from 1931 onwards. Some features had been introduced to the production series, some expressed into new prototypes; others had remained mere paper projects. Renault always strongly lobbied to attain official, and thus financed, state orders for his development projects and on 20 December 1934 he had managed to obtain one for an improved Renault UE, the Renault UE 2. One by one during 1935 and 1936 improved components were submitted to the Commission de Vincennes to be tested and modified according to the wishes of the Army. These included: reinforced pistons; a new gear box with four speeds forward and one reverse; a reinforced differential; longer front mudguards of which the back part bent upwards to form a continuous plane with the glacis, a semi-automatic attachment system for the trailer and a night light at the lower left back of the vehicle. These changes were not very fundamental — the commission was not even aware this was supposed to end in a new type — but Renault used this very fact as an argument to select the UE 2 as the replacement vehicle: the improvements could be introduced without interrupting production, whereas the switch to a completely different design might cause a fatal delay in the rearmament process. This proved to be a decisive consideration for the Army and November 1937 a choice was made for the Renault UE2 to become the type for mass production: the Chenillette de ravitaillement d'Infanterie Modèle 1937 R. An order was placed with AMX — the nationalised former Renault factory — on 3 December. Other manufacturers were employed also: in fact Fouga had already obtained an order on 2 December; Berliet would be given one on 16 March 1938.

These manufacturers however did not immediately take the Modèle 37 into production; they in fact made the Modèle 31 to complete the first production batches; only in the summer of 1939, when the French economy went into full gear to prepare for increased war production, was the gradual transition to the UE 2 really made, though some new features, such as the mudguards, appear already in the summer of 1936; from the summer of 1937 instead of the original Restor headlights the armoured type of Guicherd was fitted. The Army did not discern between the two UE types and eventually in the statistics subsumed all chenillettes received under the denominator Modèle 31. On 1 September 1939 2848 Renault UEs of both models had been manufactured. In 1940 a production of 300 vehicles per month was aimed at. To ensure such a high output Renault bought the SUP factory at Pontlieue, to start another UE 2 assembly line there. On 1 April 1940 AMX had built 1080 Renault UE2s, Fouga 260 and Berliet 310. In May monthly deliveries reached the total number of 509, made possible by emptying the factory matériel stocks; on 1 June 4977 Renault chenillettes of both models had been built, 4557 delivered; total production destined for France was about 5148, on the assumption that about 2300 vehicles had been produced after 1 September. In the seventies it was still assumed that the production realised before December 1937 — mistakenly equated to that of the Modèle 31 — was not included in this number; total production was thus overestimated at about 6200.