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Northern Pacific class A
The locomotive class that gave the 4-8-4 “Northern” its name was the class A of the Northern Pacific. Introduced in 1926, they were the first locomotives of this wheel arrangement in the USA. ALCO built a total of onl...
| Northern Pacific class ARemove | |
|---|---|
| Variant | Standard |
| Built | 1926-1927 |
| Manufacturers | ALCO |
| Wheel arrangement | 2D2 |
| Gauge | 1435 mm |
| Length | |
| Service mass | 189602 kg |
| Top speed | |
| Power | |
| Engine |
General
| Property | Northern Pacific class A Standard Remove |
|---|---|
| Built | 1926-1927 |
| Manufacturers | ALCO |
| Wheel arrangement | 4-8-4 (Northern) |
| Gauge | 1,435 mm |
Dimensions and weights
| Property | Northern Pacific class A Standard Remove |
|---|---|
| Wheelbase | 14.38 m |
| Total wheelbase | 27.43 m |
| Service mass | 189.6 t |
| Adhesion mass | 113.9 t |
| Total mass | 331.6 t |
| Rigid wheelbase | 6.17 m |
| Axle load | 28.6 t |
| Water capacity | 56,781 l |
| Fuel capacity | 21.8 t (coal) |
Boiler
| Property | Northern Pacific class A Standard Remove |
|---|---|
| Grate area | 10.684 m² |
| Firebox surface | 45.058 m² |
| Tube heating surface | 408.681 m² |
| Evaporative heating surface | 453.739 m² |
| Superheater surface | 185.063 m² |
| Total heating surface | 638.8 m² |
Power plant
| Property | Northern Pacific class A Standard Remove |
|---|---|
| Driver diameter | 1,854 mm |
| Boiler pressure | 14.5 bar |
| Expansion type | simple expansion |
| Cylinders | two, 711 x 762 mm |
Power
| Property | Northern Pacific class A Standard Remove |
|---|---|
| Power source | steam |
| Estimated power | 3,356 kW (4,563 PS) |
| Starting effort | 255.8 kN |
| Starting effort booster | 50.71 kN |
Calculated values
| Property | Northern Pacific class A Standard Remove |
|---|---|
| Factor of adhesion | 1 : 4.37 |
| Optimal speed | 80 km/h |
| Power-to-weight ratio | 17.7 kW/t |
| Heating Surface Equivalent | 1,049.2 m² |
| Cylinder volume/HSE | 1 : 577.06 |
| Adhesive weight/Total | 1 : 1.67 |
| Tractive force/Heating surface | 1 : 8.36 |
| Grate area/Heating surface | 1 : 59.79 |
| Firebox/Tube surface | 1 : 9.07 |
| Total/Superheater | 1 : 2.45 |
