Laffly S 35 T (1937)
308 made 1937-40.
The Laffly S 35 T emerged from a 1935 specification calling for a heavy 6x6 prime mover capable of towing all hevay artillery pieces in the French inventory, notably the ubiquitous 155 mm GPF modele 1917 and 155 mm Howitzer modele 1917. Laffly delivered a ladder-type 6x6 vehicle with a 4-cyl. Otto petrol engine capable of 40 kph on all terrains thanks to its unditching small wheels, winch and spade. 225 were delivered from 1937 to 1940 and it was declined into a recovery vehicle, an armoured transport and an aircraft engine starter vehicle. Ther German captured many and had Laffly delivering from parts 83 more in 1941. It was integrated in the Werhmacht as the Schwere Radschlepper laffly S 15T(f).
The Laffly S35T in brief
The company Établissements LAFFLY in Asnières (Seine) was founded in 1858 and before WWI, started producing Lorries from 1.5 tons to 16 tons payload. In the 1930s, Laffly developmed special rough-terrain vehicles intended for army contracts. Different types were tested and acquired by the French army over the years. Laffly, Licorne and Hotchkiss all took part in the production of off-road artillery tractors for all the range of French ordnance. In 1940, Hotchkiss took over Laffly but this did not changed production which like the rest of French industries were hampered by the post-1936 labour strikes.
Development
The Laffly S 35 T was develiped by the company in 1935 from a precise specification, as the army needed a tractor usable as primary mover for the 155 mm GPF (Grand Puissance Filloux). The latter was the standard heavy gun developed in 1917 and introduced in 1918. This gun was born from the frustration of the French high command towards the lack of range of French artillery, which immense majority was covered by the now aging and small rapid fire "75" born in 1897. The German Army meanwhile could pummel French lines, including rear depots wit the range and power of massive Krupp field guns. France had nothing to compare and after 1916 programs were launched to create a range og heavy artillery pieces.
The vehicle was developed from 1935 following a tender for a heavy tractor to pull the 155mm GPF, but also the 220 mm M1916 mortar and Canon de 155C modèle 1917S howitzer, and usable as heavy recovery vehicle, somewhat like the British
Scamell Pioneer. The first 60 were ordered in April 1935 at the test phase, but deliveries only began in 1937, with further orders. By September 1939, orders piled up to 445 units, but after Hotchkiss purchased Laffly and other issues, only the 60 of the first batch had been delivered. Laffly was ordered to go from a monthly delivery rate if 25 in January 1940 to 65 units by December 1940. Only 165 more were delivered before the Wehrmacht occupied Paris on June 14, 1940 with just a few recovery vehicles.
Towing the 155mm GPF
The most compelling of these was designed by Colonel Louis Filloux and eventually manufactured by Atelier de Puteaux, Bourges and Renault, provuding notably its wheeled indercarriage. This became the standard heavy field gun of the French Army from 1917 until the Second World War, also adopted by the United States as the M1917. The latter was modernized before WW2 and became the M1, and then M1A1 Long Tom, a standard of the US Army artillery in WW2.
Back in France in 1936 the lack of fast tractors suitable for towing the GPF, until then reserved to very slow caterpillar tractors, led to no only work on a new split carriage six wheeled chassis for transport, but also the fast tractor that had the right off-road capabilities to go with it. This carriage was designed in 1939 by Captain Touzard, which radically improved its and also reduced the preparation time. The GPF-T weighted 13.7 tonnes but could be towed at 36 kilometres per hour (22 mph) and so 60 guns were in service in May 1940.
Design
The Laffly S 35 T was propelled by a 6.3 litres four-cylinder engine with rated for 100 HP. It had a bore of 115 mm and a stroke of 150 mm (6232 cm³). In addition to the driver's seat, the driver's cab was large enough for two more seated. The ladder type chassis had had three driven axles (6×6), and the transmission had four forward gears and one reverse gear, plus a countershaft gear.
As a classic trait of Laffly vehicles, they also had two more axles with small auxiliary wheels mounted in front of the front axle and between the front and first rear axle. Their role was to prevent them from getting stuck on uneven terrain. The useful payload in the rear compartment, which housed the gun crew (up to 6) also comprised the ammunitions, up to 1.2 tons. The vehicle could also tow a trailer at the top speed of 40 km/h. A large spade was attached to the rear of the vehicle to maximize the full towing capacity of the cable to be used, with a pulling force of six tons. This was for the recovery vehicle.
| Specs Laffly S35T |
| Dimensions : | 5.50 m x 2.35 m x 2.85 m |
| Total weight: | 8,050 kg max |
| Useful load: | 1,200 kg |
| Crew: | 2 + gun crew |
| Propulsion: | 4-cylinder Otto, 3 litres Gasoline, 120 kN |
| Speed: | 40 km/h on road |
| Suspensions: | Front coil springs, rear leaf springs, independent wheels |
| Range: | Unknown, c400 km |
| Production | 308 (225+83) |
Variants
The experimental 35 TL with its armoured hull by Mike Bell, CC.
-Basic S 35 T primary heavy tractor
-S 35 TD ("Depannage") recovery variant with its winch and rear spade
-Laffly S 35 TL, with an armoured superstructure developed as an APC (prototypes only, 1940)
-Laffly S 35 TL C2 engine starter used by the French Armée de L'air (Air Force).
The Laffly S 35 T in service
The S 35 T were deployed with various heay artillery units organic to the best French infantry divisions in 1939-40. They were notably deployed to Belgium in May. 225 were available, as towing vehicle for heavy artillery guns of the 10 ton class. They indeed tow a variety of ordnance as specified, and aas shown by photos. Some were also deployed in Syria and North Africa. Many vehicles were captured more or less intact, and used for their intended purpose in the Wehrmacht, as artillery towing vehicles (schlepper). On this chapter, Hotchkiss was forced to deliver 83 more for the Wehrmacht under German supervision in the same Laffly plant. Captured Laffly S 35 T were used notably as towing vehicle for the famous 8,8 cm Flak 37 in France and still around in June 1944.