Data from Robert LeMassena, "The First 4-8-4 and 2-6+6-4 (almost)", Railway & Locomotive Historical Society Newsletter, Vol 21, No 1 (Winter 2001 ). pp. 4-5.
As Baldwin turned out dozens of the Erie's new 2-8-4 design, which allowed a bigger firebox than the earlier 2-8-2s, it drafted a design for a locomotive---16-46/46 2/4 DD --that would take that idea even further. And the dimensions and areas of the proposal were simply enormous, later rivalled only by the largest of articulateds.
But the 2-6-6-4 (pace, Mr LeMassena) arrangement never would be popular, mostly because the single-axle leading truck was overmatched by the rest of a very large locomotive. Erie declined to proceed with a prototype and the first 2-6-6-4s would appear five years later on the Pittsburgh & West Virginia (Locobase 301).
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 2-6-6-4 Proposed |
| Locobase ID | 11024 |
| Railroad | Erie (ERR) |
| Country | USA |
| Whyte | 2-6-6-4 |
| Number in Class | 1 |
| Road Numbers | |
| Gauge | Std |
| Number Built | |
| Builder | Baldwin |
| Year | 1929 |
| Valve Gear | Baker |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 24.34 / 7.42 |
| Engine Wheelbase (ft / m) | 59.08 / 18.01 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.41 |
| Overall Wheelbase (engine & tender) (ft / m) | 116.69 / 35.57 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 72,000 / 32,659 |
| Weight on Drivers (lbs / kg) | 432,000 / 195,952 |
| Engine Weight (lbs / kg) | 610,000 / 276,692 |
| Tender Loaded Weight (lbs / kg) | 413,000 / 187,334 |
| Total Engine and Tender Weight (lbs / kg) | 1,023,000 / 464,026 |
| Tender Water Capacity (gals / ML) | 24,000 / 90.91 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 30 / 27 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 120 / 60 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 70 / 1778 |
| Boiler Pressure (psi / kPa) | 250 / 1720 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 25" x 30" / 635x762 (4) |
| Tractive Effort (lbs / kg) | 113,839 / 51636.56 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.79 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 75 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 240 - 3.5" / 89 |
| Flue/Tube length (ft / m) | 24 / 7.32 |
| Firebox Area (sq ft / m2) | 680 / 63.17 |
| Grate Area (sq ft / m2) | 126 / 11.71 |
| Evaporative Heating Surface (sq ft / m2) | 7100 / 659.85 |
| Superheating Surface (sq ft / m2) | 3000 / 278.81 |
| Combined Heating Surface (sq ft / m2) | 10,100 / 938.66 |
| Evaporative Heating Surface/Cylinder Volume | 208.27 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 31,500 |
| Same as above plus superheater percentage | 40,950 |
| Same as above but substitute firebox area for grate area | 221,000 |
| Power L1 | 32,084 |
| Power MT | 982.40 |