The reference for locomotives and railcars
Southern Pacific class MC-1
United States | 1909 | 2 produced
collection Taylor Rush

In 1909, the Southern Pacific ordered two Mallets from Baldwin in the 2-8-8-2 wheel arrangement, which were the heaviest locomotives in the world at the time. They were intended to haul ever heavier freight trains across the Sierra Nevada. In the test runs with the two machines, the aim was to gain experience for later series production.

Since the Schmidt superheater had not yet fully established itself, a different design was chosen for the very large boiler. First there was a feedwater heater with an area of 1,221 sq ft. The high-pressure cylinders were then operated with saturated steam, which was passed through a 655 sq ft reheater before being passed on to the low-pressure cylinders.

During operation, it quickly became clear that the smoke produced by these powerful locomotives in the many tunnels posed a serious danger to the crews. Thus, the following classes from the MC-2, as well as the AC series, were built as Cab Forward. The two MC-1s were also converted into MC-2s in 1923. In 1931 they were converted to simple expansion and scrapped in 1947 and 1948 respectively.

Axle config2-8-8-2 (Mikado Mallet) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase56 ft 7 in
Fixed wheelbase15 ft
Total wheelbase83 ft 6 in
Service weight425,900 lbs
Adhesive weight394,145 lbs
Total weight606,100 lbs
Axle load50,260 lbs
Water capacity10,800 us gal
Fuel capacity3,420 us gal (oil)
Power sourcesteam
Estimated power3,000 hp (2,237 kW)
Optimal speed22 mph
Starting effort85,039 lbf
with start valve102,047 lbf
Power Plant
Driver diameter57 in
Boiler pressure200 psi
Expansion typecompound
Cylindersfour, HP: 26 x 30 in
and LP: 40 x 30 in
Grate area68.4 sq ft
Firebox area232 sq ft
Tube heating area4,941 sq ft
Evaporative heating area5,173 sq ft
Superheater area655 sq ft
Total heating area5,828 sq ft
Calculated Values
steam locomotive
last changed: 03/2023

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