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Chesapeake & Ohio H-8 “Allegheny” 2-6-6-6
The Complete Technical & Operational Biography
1941–1956
The most powerful single-unit steam locomotive ever built — 7,500 hp on the dynamometer — and the last great coal-hauler of the Appalachians.
1. The Problem (1936)
The C&O’s Alleghany Subdivision climbs 2,072 ft in 113 miles from Hinton, West Virginia to Clifton Forge, Virginia, topping out with a 13-mile ruling grade of 0.57 %. In the late 1930s the railroad was moving 11,500-ton coal trains at 12–15 mph with triple-headed 2-8-8-2 Mallets plus pushers.
Goal: one locomotive class that could take the same train up the hill at 45 mph.
2. Lima’s Answer: Super-Power Taken to the Limit
Lima Locomotive Works enlarged its proven 2-6-6-4 “Super-Power” formula, added a six-wheel trailing truck to carry an even deeper firebox, and delivered the heaviest single rigid-frame steam locomotive ever built.
3. Construction & Delivery
- 1941: 10 units, 1600–1609 (cost $230,600 each)
- 1948: 50 units, 1610–1659 (post-war price $392,500 each)
- Total built: 60 — the largest single class of 2-6-6-6 in the world
4. Technical Specifications (1948 batch)
| Item | Value |
|---|---|
| Wheel arrangement | 2-6-6-6 simple articulated |
| Builder | Lima Locomotive Works |
| Engine-only weight | 751,830 lb (341.1 t) — heaviest single rigid unit ever |
| Total weight engine + tender | ~1,247,000 lb (565 t) |
| Axle load (first driver) | 86,700 lb — highest ever |
| Driver diameter | 67 in |
| Boiler pressure | 260 psi |
| Cylinders (4) | 22½ × 33 in |
| Grate area | 135 sq ft + 118 in combustion chamber |
| Starting tractive effort | 110,211 lbf |
| Drawbar horsepower (1948 Lima test) | 7,498 hp peak — 6,700–6,900 hp sustained at 45 mph |
| Tender capacity | 25 tons coal + 25,000–26,500 gal water |
5. Operational Career 1941–1956
Primary territory: Hinton – Clifton Forge (Alleghany Sub) and Thurmond – Russell (New River Sub)
Typical train: 140 cars, 11,500 tons, double-headed
Single-unit capability: 13,500 tons on level track
Service speed: 45 mph sustained on 0.57 % grade
Last run: 1956 — dieselization complete
6. Head-to-Head vs Union Pacific Big Boy
| Category | Big Boy 4-8-8-4 | Allegheny 2-6-6-6 | Winner |
|---|---|---|---|
| Starting TE | 135,375 lbf | 110,211 lbf | Big Boy |
| Drawbar HP | ~6,300 hp | 7,498 hp (record) | Allegheny |
| Speed on grade | 50–60 mph on 1.55 % | 45 mph on 0.57 % | Big Boy |
| Years in service | 18 | 15 | Big Boy |
| Survivors | 8 (one running) | 2 (both static) | Big Boy |
| Still operating 2025 | Yes — 4014 | No | Big Boy |
7. Survivors Today (December 2025)
| Number | Year | Location | Status |
|---|---|---|---|
| 1601 | 1941 | Henry Ford Museum, Dearborn, MI | Indoor static — centerpiece exhibit |
| 1604 | 1941 | B&O Railroad Museum, Baltimore, MD | Indoor static — survived 1985 flood |
All others scrapped 1952–1960.
8. Why No Allegheny Ever Returned to Steam
- 86,700 lb axle load — too heavy for almost every heritage railroad in America
- No existing C&O/Chessie/CSX steam program
- Cost of restoration estimated >$15 million (2025 dollars)
- Both survivors indoors and treated as museum artifacts
9. Final Thought
The Allegheny produced more raw horsepower than any other single steam locomotive ever tested. For fifteen glorious years it dragged the heaviest coal trains in the world up the mountains that gave it its name.
But when the diesels came, the mountains didn’t need giants anymore.
End of story.
The mountains are quiet now.
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