Southern Pacific class M-4
United States 1899 105 produced
A total of 105 of these Moguls were put into service by the Southern Pacific beginning in 1899. They were from ALCO, most of them from Cooke and the rest from Schenectady. Starting in 1920, they were rebuilt with a superheater. They were used in mainline service up until the 1940s and as switchers into the 1950s. Preserved today is number 1673, which is in Tucson, Arizona and has been cosmetically restored since 2000.
Technical data
General
| Property | as built | superheated |
|---|---|---|
| Built | 1899-1901 | 1920-1922 |
| Manufacturers | Cooke, Schenectady | Sacramento |
| Wheel arrangement | 2-6-0 (Mogul) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | as built | superheated |
|---|---|---|
| Wheelbase | 7.09 m | |
| Total wheelbase | 14.24 m | |
| Service mass | 64.7 t | 71.6 t |
| Adhesion mass | 56.1 t | 61.1 t |
| Rigid wheelbase | 4.62 m | |
| Axle load | 18.7 t | 20.4 t |
| Water capacity | 17,034 l | |
| Fuel capacity | 9.1 t (coal) | |
Boiler
| Property | as built | superheated |
|---|---|---|
| Grate area | 2.81 m² | |
| Firebox surface | 15.608 m² | 14.493 m² |
| Tube heating surface | 180.882 m² | 125.419 m² |
| Evaporative heating surface | 196.49 m² | 139.912 m² |
| Total heating surface | 196.5 m² | 164.9 m² |
| Superheater surface | 24.991 m² | |
Power plant
| Property | as built | superheated |
|---|---|---|
| Driver diameter | 1,600 mm | |
| Boiler pressure | 13.1 bar | |
| Expansion type | simple expansion | |
| Cylinders | two, 508 x 711 mm | |
Power
| Property | as built | superheated |
|---|---|---|
| Power source | steam | |
| Estimated power | 634 kW (862 PS) | 820 kW (1,115 PS) |
| Starting effort | 127.7 kN | |
Calculated values
| Property | as built | superheated |
|---|---|---|
| Factor of adhesion | 1 : 4.31 | 1 : 4.69 |
| Optimal speed | 31 km/h | 39 km/h |
| Power-to-weight ratio | 9.8 kW/t | 11.4 kW/t |
| Heating Surface Equivalent | 274.5 m² | 262.4 m² |
| Cylinder volume/HSE | 1 : 1,050.14 | 1 : 1,098.86 |
| Adhesive weight/Total | 1 : 1.15 | 1 : 1.17 |
| Tractive force/Heating surface | 1 : 13.57 | 1 : 16.18 |
| Grate area/Heating surface | 1 : 69.93 | 1 : 58.68 |
| Firebox/Tube surface | 1 : 11.59 | 1 : 8.65 |
| Total/Superheater | 1 : 5.60 |
