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Union Pacific class 3900 “Challenger”
In the 1930s, the Union Pacific was looking for a more powerful locomotive that could haul heavy passenger and freight trains faster over mountain lines like the Wasatch Grade. Although a twelve-coupled locomotive was...
| Union Pacific class 3900 “Challenger”Remove | |
|---|---|
| Variant | CSA-1, CSA-2 |
| Built | 1936-1937 |
| Manufacturers | ALCO |
| Wheel arrangement | (2C)C2 ma |
| Gauge | 1435 mm |
| Length | 37157 mm |
| Service mass | 257165 kg |
| Top speed | 113 km/h |
| Power | |
| Engine |
General
| Property | Union Pacific class 3900 “Challenger”CSA-1, CSA-2 |
|---|---|
| Built | 1936-1937 |
| Manufacturers | ALCO |
| Wheel arrangement | 4-6-6-4 (Challenger) |
| Gauge | 1,435 mm |
Dimensions and weights
| Property | Union Pacific class 3900 “Challenger”CSA-1, CSA-2 |
|---|---|
| Length | 37.16 m |
| Wheelbase | 18.26 m |
| Total wheelbase | 30.14 m |
| Service mass | 257.2 t |
| Adhesion mass | 181.4 t |
| Total mass | 397.8 t |
| Rigid wheelbase | 3.71 m |
| Axle load | 30.3 t |
| Water capacity | 68,137 l |
| Fuel capacity | 20 t (coal) |
Boiler
| Property | Union Pacific class 3900 “Challenger”CSA-1, CSA-2 |
|---|---|
| Grate area | 10.057 m² |
| Firebox surface | 50.911 m² |
| Tube heating surface | 441.847 m² |
| Evaporative heating surface | 492.758 m² |
| Superheater surface | 153.29 m² |
| Total heating surface | 646.0 m² |
Power plant
| Property | Union Pacific class 3900 “Challenger”CSA-1, CSA-2 |
|---|---|
| Driver diameter | 1,753 mm |
| Boiler pressure | 17.6 bar |
| Expansion type | simple expansion |
| Cylinders | four, 559 x 813 mm |
Power
| Property | Union Pacific class 3900 “Challenger”CSA-1, CSA-2 |
|---|---|
| Power source | steam |
| Estimated power | 3,729 kW (5,070 PS) |
| Top speed | 113 km/h |
| Starting effort | 432.8 kN |
Calculated values
| Property | Union Pacific class 3900 “Challenger”CSA-1, CSA-2 |
|---|---|
| Factor of adhesion | 1 : 4.11 |
| Optimal speed | 53 km/h |
| Power-to-weight ratio | 14.5 kW/t |
| Heating Surface Equivalent | 1,053.9 m² |
| Cylinder volume/HSE | 1 : 756.57 |
| Adhesive weight/Total | 1 : 1.42 |
| Tractive force/Heating surface | 1 : 13.99 |
| Grate area/Heating surface | 1 : 64.24 |
| Firebox/Tube surface | 1 : 8.68 |
| Total/Superheater | 1 : 3.21 |
