Southern Railway (USA) class Ps-4
The Ps-4 was Southern's premier class of Pacifics and also one of the most famous passenger steam locomotives in the United States. It was based on the USRA Heavy Pacific but had some adjustments such as smaller drivers, a shorter boiler and depending on the batch a Worthington or Elasco feedwater heater. Even with the driver diameter of 73 inches, they could pull 14 cars at 80 mph (129 km/h).
In two batches, a total of 44 Ps-4s were delivered to the Southern, twelve to the Cincinnati, New Orleans and Texas Pacific and eight to the Alabama Great Southern. The second batch locomotives were initially painted in a special Virginia Green and Gold livery following President Fairfax Harrison's visit to Great Britain. Today only number 1401 remains, which is not operational.
Technical data
General
| Property | 1923 variant | 1926 variant |
|---|---|---|
| Built | 1923-1925 | 1926-1928 |
| Manufacturers | ALCO, Baldwin | |
| Wheel arrangement | 4-6-2 (Pacific) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | 1923 variant | 1926 variant |
|---|---|---|
| Wheelbase | 11.00 m | |
| Service mass | 136.1 t | 137.9 t |
| Adhesion mass | 81.6 t | |
| Total mass | 224.8 t | 256.6 t |
| Rigid wheelbase | 3.96 m | |
| Axle load | 27.2 t | |
| Water capacity | 37,854 l | 52,996 l |
| Fuel capacity | 14.5 t (coal) | |
Boiler
| Property | 1923 variant | 1926 variant |
|---|---|---|
| Grate area | 6.54 m² | 6.55 m² |
| Firebox surface | 29.172 m² | 26.942 m² |
| Tube heating surface | 316.358 m² | 315.871 m² |
| Evaporative heating surface | 345.53 m² | 342.813 m² |
| Superheater surface | 79.897 m² | 84.077 m² |
| Total heating surface | 425.4 m² | 426.9 m² |
Power plant
| Property | 1923 variant | 1926 variant |
|---|---|---|
| Driver diameter | 1,854 mm | |
| Boiler pressure | 13.8 bar | |
| Expansion type | simple expansion | |
| Cylinders | two, 686 x 711 mm | |
Power
| Property | 1923 variant | 1926 variant |
|---|---|---|
| Power source | steam | |
| Estimated power | 2,274 kW (3,092 PS) | |
| Top speed | 129 km/h | |
| Starting effort | 211.4 kN | |
Calculated values
| Property | 1923 variant | 1926 variant |
|---|---|---|
| Factor of adhesion | 1 : 3.79 | |
| Optimal speed | 66 km/h | |
| Power-to-weight ratio | 16.7 kW/t | 16.5 kW/t |
| Heating Surface Equivalent | 651.2 m² | 645.7 m² |
| Cylinder volume/HSE | 1 : 806.87 | 1 : 813.75 |
| Adhesive weight/Total | 1 : 1.67 | 1 : 1.69 |
| Tractive force/Heating surface | 1 : 10.38 | 1 : 10.34 |
| Grate area/Heating surface | 1 : 65.05 | 1 : 65.17 |
| Firebox/Tube surface | 1 : 10.84 | 1 : 11.72 |
| Total/Superheater | 1 : 4.32 | 1 : 4.08 |
