The Central Mexicano also received a total of 15 locomotives of the US type of the Mason-Fairlie in 1890, which essentially corresponded to the British Single Fairlie. Under the boiler barrel was a bogie that held the cylinders, three driving axles and a leading axle. At the rear, the tender rested on a three-axle bogie. The firebox hang between the bogies and could therefore be built deep enough.

In contemporary depictions, the locomotives were described as a successful design with a comfortable cab. Although they could negotiate the tightest curves with ease, the running smoothness was apparently not particularly good. Nevertheless, all locomotives were already scrapped between 1899 and 1908. This is probably due to the fact that more modern locomotives without moving steam lines were now available.

Unusual for a North-American 4-8-0, the NdeM ordered their classes PR-7 and PR-8 mainly for passenger service. A thought behind this may have been that a Twelve-wheeler had more adhesive weight than a similarly sized Pacific. Their driver diameter of 67 inches or 1,702 mm was larger than that of any US 4-8-0 and matched that of the fast European locomotives of this wheel arrangement.

Baldwin built a single PR-7 in 1924 that was numbered 5-A and later renumbered to 2856. It had the same boiler as the KR-1 Mikados and the MR-6 Pacifics, but this was mounted higher in the PR-7 to make space for the wide firebox above the last set of drivers. Nevertheless, the top of the drivers protruded into the firebox. This was possible since this oil burner did not need a continuous ash pan. In contrast to its sisters with the same boiler, it had an Elesco feed water heater. The cylinders had square dimensions with a bore and stroke of 28 inches each.

Baldwin delivered five more in 1935 which had a larger boiler. These were called class PR-8 and numbered 3000 to 3004. The main increase in the firebox heating surface could be attributed to the thermic syphons. With a service weight of 288,000 pounds or 130.5 tonnes, they were the heaviest 4-8-0 locomotives ever. The dimensions of the cylinders and drivers had not been changed and also the boiler pressure remained unchanged. The PR-7 was retired in 1962 and the last PR-8 was gone in the following year.

The articulated 2-6-6-2 of the class HR-01 were the heaviest locomotives used by the Mexican State Railway on their three-foot narrow gauge network. In general dimensions they were similar to the Uintah Railway No. 50 and 51, but were tender locomotives. Without the need to store water and fuel oil on the locomotive itself, they had a larger boiler. The included a wide firebox with 55 square feet of thermic syphons. The drivers had a diameter of 43 inches and the cylinders measured 15 by 22 inches, controlled by Baker valve gear.

The first six were built by ALCO-Schenectady in 1928 with the works numbers 67707 to 67712. They were initially numbered 240 to 245, but renumbered 361 to 366 in 1930. Numbers 367 and 368 were built in 1934 with the works numbers 68644 and 68645. These were the only ones with an Elesco feed water heater. The final two, numbered 369 and 370, were delivered in 1936 with the works numbers 68773 and 68774. The four locomotives built in the thirties were six tons heavier and had a larger tender that contained 3,000 instead of 2,500 gallons of oil.

They were used in passenger and freight service. On the level they were rated for a train of 800 tons at 60 km/h or 37 mph. On a two percent grade they managed to reach 25 km/h (16 mph) with 410 tons and on four percent, it was 12 km/h (7 mph) with 230 tons. Their tasks became less with the conversion of narrow gauge lines to standard gauge. One was taken out of service in 1951 and the others in 1953.

The Nacional de Mexico received ten Hudsons from ALCO in Schenectady in 1937. With an adhesive weight of 170.000 pounds, they were among the lightest North American locomotives with this wheel arrangement. Thanks to their oil firing, they were able to stay in service well into the 1960s. Number 2708 survives today, retired in 1963 and on display in the Plaza de las Tres Centurias in Aguascalientes.

The Nacionales de México class G-030 consisted of 20 three-foot gauge Consolidations delivered by Baldwin in 1921. The outside frames were designed in such a way that a later conversion to standard gauge would have been possible. They were fired with oil and were designed for lines with gradients of up to 4.5 percent and curve radii of up to 21 degrees (85 meters).

In reality, however, there were only a few modifications that were carried out by the NdeM shortly after delivery. These affected, for example, the blastpipe, the position of the air pump and the fire door. Eight more followed in 1924, which had a larger firebox and were designated class G-033. They became the standard freight locomotive in rural areas and survived until the late 1960s.

The last and heaviest Double Fairlies ordered by the Mexican Railway were the three members of the class R-3, numbered 183 to 185, which were built by Vulcan Foundry in 1911. They were ordered for the Orizabo-Esperanza line and had to haul 300 tons on inclines of 1 in 25, while negotiating curves of five chains (100 metres). To achieve the desired power, they weighed 138 tons with an axle load of 23 tons. This made them the heaviest and most powerful Double Fairlies ever built.

Despite their British builder, they had a typical American appearance. The water tanks above the boiler had a total capacity of 4,800 imperial gallons and made the complete locomotives look very bulky. This was further increased when they were converted to burn oil, with the oil tanks above the water tanks. Their careers ended in 1923 after the line had been electrified.

In 1903, Baldwin built a light three-foot gauge 2-6-0 for the Merida a Peto in Mexico that was numbered 12 and named “Catalina A de Casasus”. It carried the works number 21935 and belonged to the Baldwin type 8-20 D 115. The wood burner weighed 52,000 pounds, of which 43,000 rested on the drivers. At 45,000 pounds, the tender was not much lighter than the locomotive. The railroad became part of the Unidos de Yucatan in 1908 and the locomotive was renumbered to 62.

Five more locomotives were built in 1928 which were nearly identical, but burned oil and were 5,000 pounds heavier. They carried the numbers 75 to 79. 62 was retired in 1948 and 75 and 79 followed in 1962. The other three were sold to the Unidos de Sureste. No. 260, the earlier No. 76, was sold to Disney in 1969 for service at Disneyland in Anaheim, California. For this it was rebuilt in 1971, renamed to “Lilly Belle” and received the number 2.