| Union Pacific Challenger | |
|---|---|
| UP 3985 running through Alton, Iowa in October 2008 | |
| Power type | Steam |
| Builder | American Locomotive Company (ALCO) |
| Build date | 1936-1943 |
| Configuration | 4-6-6-4 |
| UIC classification | (2′C)C2′ h4 |
| Gauge | 4 ft 8 1⁄2 in (1,435 mm) |
| Driver diameter | 69 in (1,753 mm) |
| Wheelbase | 60 ft 4 1⁄2 in (18.402 m) Engine 121 ft 10 7⁄8 in (37.157 m) Engine + tender |
| Weight on drivers | 404,000 lb (183.3 t) |
| Locomotive weight | 627,900 lb (284,800 kg) |
| Tender weight | 446,000 lb (202,000 kg) |
| Locomotive & tender combined weight |
1,073,900 lb (487,100 kg) |
| Fuel type | Coal, UP 3985 converted to No. 5 fuel oil |
| Fuel capacity | 32 short tons (29 t) 6,450 US gal (24,400 l; 5,370 imp gal) UP3985 |
| Water capacity | 25,000 US gal (95,000 l; 21,000 imp gal) |
| Boiler pressure | 280 lbf/in² (1.93 MPa) |
| Heating surface: Tubes |
527 sq ft (49.0 m2) |
| Heating surface: Flues |
3,687 sq ft (342.5 m2) |
| Heating surface: Firebox |
500 sq ft (46 m2) |
| Heating surface: Total |
4,795 sq ft (445.5 m2) |
| Superheater area | 2,162 sq ft (200.9 m2) |
| Cylinders | Four |
| Cylinder size | 21 × 32 in (533 × 813 mm) |
| Top speed | 70 mph (110 km/h) |
| Tractive effort | 97,350 lbf (433.03 kN) |
| Career | Union Pacific Railroad |
| Class | 4664-4 |
| Number in class | 105 |
Built between 1936 and 1943, the Challengers were nearly 122 feet long and weighed more than one million pounds. Articulated like their big brother, the Union Pacific Big Boy, the Challengers had a 4-6-6-4 wheel arrangement. They operated over most of the Union Pacific system, primarily in freight service, but a few were assigned to passenger trains operating through mountain territory to California and Oregon. The 105 locomotives were built specifically by ALCO for Union Pacific having drawn on much of the Big Boy's experience.
The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox. Each set of driving wheels has its own steam cylinder. In essence, the result is two engines under one boiler.
Two examples survive today: Union Pacific 3985, used for excursion services by Union Pacific and Union Pacific 3977, on static display in North Platte, NE.
|
|||||||||||||||||
|
||||||||