Data from 1930 Locomotive Cyclopedia and confirmed by CV 1957 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange; and American Locomotive Company, Order No S-1630, "Class 2104 S 419" data card and builder's photo.. (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error and for his 19 February 2024 email supplying the Alco builder's card and booster tractive effort..) Works numbers were 67671 in October 1928, 67672-67678 in November, 67767-67768 in December.
Firebox had 80 sq ft (7.4 sq m) in thermic syphons and 22 sq ft (2 sq m) in three Security arch tubes. The inverted wagon top boiler used Elesco's familiar K-50 cylindrical open feed water heater mounted on the shelf ahead of the smokebox top. Valve gear had limited cutoff, Standard BK mechanical stoker fed the firebox, Franklin C-2 50% cutoff-limited trailing-truck booster supplied additional starting tractive effort.
The Cyclopedia table shows Walschaert, the diagram showed Baker Long Lap valve gear . The builder's photo settled the question in favor of the Baker version.
They were relatively light, small, and low-drivered. Nevertheless, these engines rattled windows and shook the ground, according to a December 1993 Trains recollection. And they weren't kind to the rails.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | T-3a |
| Locobase ID | 94 |
| Railroad | Central Vermont (CNR) |
| Country | USA |
| Whyte | 2-10-4 |
| Number in Class | 10 |
| Road Numbers | 700-709 |
| Gauge | Std |
| Number Built | 10 |
| Builder | Alco-Schenectady |
| Year | 1928 |
| Valve Gear | Baker |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 22 / 6.71 |
| Engine Wheelbase (ft / m) | 44.20 / 13.47 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.50 |
| Overall Wheelbase (engine & tender) (ft / m) | 82.19 / 25.05 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 285,000 / 129,274 |
| Engine Weight (lbs / kg) | 419,000 / 190,055 |
| Tender Loaded Weight (lbs / kg) | 269,600 / 122,289 |
| Total Engine and Tender Weight (lbs / kg) | 688,600 / 312,344 |
| Tender Water Capacity (gals / ML) | 13,500 / 51.14 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 20 / 18 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 95 / 47.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 60 / 1524 |
| Boiler Pressure (psi / kPa) | 250 / 1720 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 27" x 32" / 686x813 |
| Tractive Effort (lbs / kg) | 82,620 / 37475.85 |
| Booster (lbs) | 13,100 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.45 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 33 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 192 - 3.5" / 89 |
| Flue/Tube length (ft / m) | 22 / 6.71 |
| Firebox Area (sq ft / m2) | 423 / 39.30 |
| Grate Area (sq ft / m2) | 84.40 / 7.84 |
| Evaporative Heating Surface (sq ft / m2) | 4703 / 436.92 |
| Superheating Surface (sq ft / m2) | 2208 / 205.13 |
| Combined Heating Surface (sq ft / m2) | 6911 / 642.05 |
| Evaporative Heating Surface/Cylinder Volume | 221.74 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 21,100 |
| Same as above plus superheater percentage | 27,852 |
| Same as above but substitute firebox area for grate area | 139,590 |
| Power L1 | 31,459 |
| Power MT | 1216.76 |
