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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 | 4664-3 and 4 |
| Built | 1942-1943 |
| Manufacturers | ALCO |
| Wheel arrangement | (2C)C2 ma |
| Gauge | 1435 mm |
| Length | 37157 mm |
| Service mass | 284403 kg |
| Top speed | 113 km/h |
| Power | |
| Engine |
General
| Property | Union Pacific class 3900 “Challenger”4664-3 and 4 |
|---|---|
| Built | 1942-1943 |
| Manufacturers | ALCO |
| Wheel arrangement | 4-6-6-4 (Challenger) |
| Gauge | 1,435 mm |
Dimensions and weights
| Property | Union Pacific class 3900 “Challenger”4664-3 and 4 |
|---|---|
| Length | 37.16 m |
| Wheelbase | 18.40 m |
| Total wheelbase | 32.51 m |
| Service mass | 284.4 t |
| Adhesion mass | 183.1 t |
| Total mass | 482.4 t |
| Rigid wheelbase | 3.71 m |
| Axle load | 30.5 t |
| Water capacity | 94,635 l |
| Fuel capacity | 25.4 t (coal) |
Boiler
| Property | Union Pacific class 3900 “Challenger”4664-3 and 4 |
|---|---|
| Grate area | 12.263 m² |
| Firebox surface | 55.928 m² |
| Tube heating surface | 391.587 m² |
| Evaporative heating surface | 447.514 m² |
| Superheater surface | 218.787 m² |
| Total heating surface | 666.3 m² |
Power plant
| Property | Union Pacific class 3900 “Challenger”4664-3 and 4 |
|---|---|
| Driver diameter | 1,753 mm |
| Boiler pressure | 19.3 bar |
| Expansion type | simple expansion |
| Cylinders | four, 533 x 813 mm |
Power
| Property | Union Pacific class 3900 “Challenger”4664-3 and 4 |
|---|---|
| Power source | steam |
| Estimated power | 4,325 kW (5,880 PS) |
| Top speed | 113 km/h |
| Starting effort | 433.0 kN |
Calculated values
| Property | Union Pacific class 3900 “Challenger”4664-3 and 4 |
|---|---|
| Factor of adhesion | 1 : 4.15 |
| Optimal speed | 61 km/h |
| Power-to-weight ratio | 15.2 kW/t |
| Heating Surface Equivalent | 1,164.7 m² |
| Cylinder volume/HSE | 1 : 623.76 |
| Adhesive weight/Total | 1 : 1.55 |
| Tractive force/Heating surface | 1 : 13.57 |
| Grate area/Heating surface | 1 : 54.33 |
| Firebox/Tube surface | 1 : 7.00 |
| Total/Superheater | 1 : 2.05 |
