The reference for locomotives and railcars
Southern Railway (USA) class Ms-2
United States | 1915 | 7 produced

For the well-known Saluda grade of more than four percent, the Southern was looking for a locomotive with a particularly high tractive effort. This is where the idea came up of accommodating additional driven axles in the tender and thus using the tender as an additional adhesive weight. There were several designs, of which only the Ms-2 made it to seven.

As with all of these experimental machines, the Ms-2 was created from a conventional steam locomotive and the frame of another, older locomotive, on which a tender body was mounted. The modern class Ms Mikado was used as the locomotive, while the frame of the tender came from an older Consolidation. The five machines assembled in this way left the Southern Railway workshops in Spencer, North Carolina in 1915. A pipe went directly from the superheater exit into the tender, supplying steam to the rear engine when needed.

While the locomotive's coupling wheels were 63 inches, the tender's coupling wheels were only 50 inches, which must have led to an unusual exhaust noise. The tender's cylinders were bushed from the original 20 to 18 inches in diameter. The cylinders of the locomotive were also bushed from 27 to 26 inches to save steam. Compared to the original Ms, 1,400 instead of the previous 1,100 tons could now be towed on a gradient of 1.7 percent.

In addition to the Ms-2, other Mikados were built with a tender with a 2-6-0 wheel arrangement or locomotives with a 2-10-2 wheel arrangement with a tender with a 2-6-0 wheel arrangement. What they all had in common was the clearly decreasing tractive effort as the tender emptied. While tank locomotives still have a significant weight even with almost empty supplies, the empty weight of the tender was very low. In addition, the exhaust from the rear engine was blown into the air above the tender, which must have reduced the draft in the boiler. Just a few years later, the Ls-1 class Mallets took over the Saluda grade.

ManufacturerSouthern Railway
Axle config2-8-2+2-8-0T (Duplex) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase34 ft 9 in
Fixed wheelbase16 ft 6 in
Service weight502,940 lbs
Adhesive weight215,700 lbs
Axle load54,940 lbs
Water capacity7,500 us gal
Fuel capacity24,000 lbs (coal)
Power sourcesteam
Estimated power2,200 hp (1,641 kW)
Optimal speed29 mph
Starting effort47,883 lbf
Booster23,134 lbf
Power Plant
Driver diameter63 in
Boiler pressure175 psi
Expansion typesimple
Cylinderstwo, 26 x 30 in
Grate area53.3 sq ft
Firebox area212 sq ft
Tube heating area3,019 sq ft
Evaporative heating area3,231 sq ft
Superheater area699 sq ft
Total heating area3,930 sq ft
Calculated Values
steam locomotive
powered tender
J. Hainen
last changed: 02/2024

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