As a successor to the Pacific locomotives of the series 231-011 to 060, starting in 1914 the État had the first batch of the locomotives built, which were later to bear the numbers 231-501 to 783. The new locomotives were also four-cylinder compounds, but were superheated at the same time. The first series comprised ten locomotives, of which only six were delivered when the Germans marched into Lille. The other four locomotives were brought to Germany after completion. Other batches were built by different manufacturers, including the North British Locomotive Company.

When they were delivered, they were already state of the art, which was also found in other French express locomotives. This included a Du Bousquet-De Glehn type layout, in which the high-pressure cylinders were located on the outside and pushed far to the rear because they drove the middle driving axle. Meanwhile, the low-pressure cylinders were on the inside, driving the first driving axle. In addition, they had a cloverleaf-shaped blast pipe and a tender with a scoop for filling water at full speed. Between 1933 and 1949 the locomotives were rebuilt in various forms, resulting in a total of six types. The changes affected different forms of valve gear, but some were also provided with feedwater heaters or a longer smokebox.

Among the total of 283 locomotives that had been manufactured until 1922 were some designated as “Pacific TP” that had been delivered to the PO and the Alsatian Railway during the war as relief. When the SNCF was founded, these were designated 231 C, D, F, G, H and J, together with the six designs delivered to the État. After some lines around Paris had been electrified from 1937, their service area was reduced. After modern diesel locomotives had also taken over the express service on non-electrified lines, the last journey of a 231 G took place in September 1968. One of these 231 Gs is still operational today.

In 1913, the État had a series of 70 Consolidation freight locomotives built by three French manufacturers. The next 200 pieces were to follow from 1916, also from the same manufacturers, but this was not possible due to the change in production during the First World War. Thus the order was given to the British companies Nasmyth-Wilson, North British and the Vulcan Foundry. A further 70 were ordered by the armed forces and also manufactured by North British and the Vulcan Foundry.

Unlike most other heavy French locomotives of the time, they had simple steam expansion engines. The power was transmitted to the third coupled axle. As superheater, the British design according to Robinson was used. The running gear included a Zara bogie that connected the leading axle to the first coupled axle. The maximum deflection of the leading axle was 80 mm on both sides.

Six of the total of 270 engines for the État never went into service because they were already sunk along with their transport ship on the way to France off Cornwall. In 1920, the engines of the armed forces were divided equally between the Est and the PLM. With the creation of SNCF in 1938, the État engines became the 3-140 C, the Est the 1-140 C and the PLM the 5-140 K.

The SNCF relocated almost all of the engines from the former Est to the east of the country. They were not only used in front of freight trains, but also in front of passenger trains and sometimes even in front of express trains. It was not until 1971 that the last passenger service with one of the locomotives was discontinued. On September 24, 1975, the last freight train in France with steam traction was hauled by the 1-140 C 287. Today there are still eight pieces, three of which are still in working order.

In 1912, the État received 20 express 4-6-0 locomotives with an axle load of only 16.3 tonnes from SACM of Belfort which were numbered 781 to 800. The locomotives were used for boat trains from Paris to either Cherbourg or Dieppe and received the nickname “Jocondes”, what stands for “Mona Lisas” in French. They had four simple cylinders mounted in line, which drove the first and second driving axles. The outside cylinders were controlled by the inside ones via rocking levers.

Some locomotives from the series received upgrades like an ACFI feed water heater, a Kylchap exhaust or long-travel valves. They delivered an indicated output of 1.200 hp and six which were rebuilt to a boiler pressure of 14 instead of 12 bars delivered even 1,265 hp. Number 800 received a streamlined casing that was developed with the help of a one-tenth scale model inside a wind tunnel, but this was removed later. The SNCF designated the standard variant 3-230 J, while the six with increased boiler pressure became 3-230 L. 18 were withdrawn and scrapped in 1953 or 1954 and the last two met the same fate in 1956.

To eliminate the oscillations and the hammer blow of steam locomotives, Jean-Jacques Heilmann was the first one to develop an electric transmission for steam locomotives. His first design of 1890 included some sort of generator car that used a boiler that powered a triple-expansion compound steam engine. This turned a 360 kW generator that delivered its power to three carriages with four traction motors each.

The first working prototype of a similar design was completed in 1893 and called “La Fusée Electrique” (“The Electric Rocket”). The steam engine now only had two-stage expansion and was designed with the help of the Swiss SLM. A BBC generator rated at 500 kW powered eight traction motors in the two four-axle bogies of the locomotive. Trial runs over approximately 2,000 km were successful, since they showed very smooth running characteristics and a top speed of 107 km/h.

There was some interest from different countries, but initially there were no orders. Frequently raised points were that these locomotives were too complicated, too expensive and too heavy. Finally, the French Ouest ordered two locomotives which were somewhat heavier than the prototypes. These were completed in 1897 and numbered 8001 and 8002. On test runs, these had no problems hauling a 250 tonne train at 100 km/h. Nevertheless, there were no further orders and these two were scrapped. Similar types of power transmission were only implemented later with internal combustion engines.

In 1860, the Ouest had the first of these tank locomotives made as helpers on ramps. They had the wheel arrangement 0-6-0T and a firebox that overhung the coupled axles at the rear. The coal was carried in pockets in front of the footplate. After the suitability for shunting service became known, their number rose to 104. Some were built to haul freight trains on the Paris Ring and had larger water tanks. Over the years they were upgraded, for example with a cab. The SNCF took over 41 more in 1938 as 1-030 TA and 3-030 TA. In 1950 there were 29 left and the last disappeared in 1967.

At a time when attempts were being made to use the largest possible wheels to achieve high speeds while keeping the center of gravity low, some curious designs emerged. In 1855 Blavier and Larpent built the “L'Aigle” (“The Eagle”) with 9 ft 4 in wheels on the French Ouest. Their goal was to double the speed of the Cramptons. Since these had already reached 120 km/h at that time, this goal was hardly realistic to achieve.

With this wheel diameter, a boiler, which was usually above the axles, would have been very high above the top of the rails. At that time, everyone was convinced that a low center of gravity was the most important criterion for smooth running and developed many long boiler type locomotives, which had a thin and long, overhanging boiler to achieve the lowest possible center of gravity. Since this was not possible with the “L'Aigle”, completely new paths were taken.

The actual boiler, with a small diameter, lay below the axles and was connected to a second, cylindrical barrel, which lay above the axles. Although the boiler had sufficient volume, there were no smoke tubes in the upper boiler body. This made it impossible to produce enough steam for the large cylinders at higher speeds. Thus, the one-off never made it into commercial service and the allegedly achieved speed of 100 mph must be doubted.

Since the No. 2501 to 2540 ten-wheelers had drivers too small for express service, the French Ouest took these as basis for a new type of express locomotives built from 1901. They got larger drivers with a diameter of 1.910 instead of 1.750 mm and were otherwise very similar. Like their basis, they were four-cylinder de Glehn compounds. Of the first 20 locomotives, the first ten were right hand drive and the rest left hand drive.

The next 50 locomotives still had a boiler with a Belpaire firebox and serve tubes, but now had piston instead of slide valves. The last 50 were only built by the German companies Borsig and Henschel and had a superheater. The SNCF designated them 230 C. After the Ouest was taken over by the État, they ordered 85 identical locomotives in 1912 and numbered them 621 to 705.

After the compound locomotives of the Webb type were apparently successful in Great Britain, the Ouest also ordered one locomotive for trials. Like the British locomotives, it had two small outer high-pressure cylinders driving the second driving axle and one large inner low-pressure cylinder driving the first driving axle. These two axles were not coupled to each other. The number 500 was rebuilt in the meantime, but was already retired in 1901.