Data from Birmingham & North Western Locomotive Diagrams supplied in 2025 by Allen Stanley from his extensive Rail Data Exchange. Works number was 5510 in February 1881.
This small Eight-wheeled American-type locomotive was a one-off for the M&O, joining a handful of older Philadelphia-built 4-4-0s. Regardless of its unicorn quality, which included a relatively tiny grate,, the 77 remained on the M&O roster for decades. In 1885, the M&O converted from its original five-foot gauge to standard gauge.
25 years later, successor Gulf, Mobile & Ohio sold the 77 (possibly renumbered 72) to short-line Birmingham & North Western as their #10.. Running over 48 1/2 miles, all in Tennessee, the line linked Jackson to Dyersburg.
The 10 disappeared from the roster by 1927, when the Gulf, Mobile & Northern absorbed the B&NW .
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 77 |
| Locobase ID | 16686 |
| Railroad | Mobile & Ohio |
| Country | USA |
| Whyte | 4-4-0 |
| Number in Class | 1 |
| Road Numbers | 77/72 |
| Gauge | 5' |
| Number Built | |
| Builder | Baldwin |
| Year | 1881 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 8.54 / 2.60 |
| Engine Wheelbase (ft / m) | 22.54 / 6.87 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.38 |
| Overall Wheelbase (engine & tender) (ft / m) | 48.79 / 14.87 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 54,000 / 24,494 |
| Engine Weight (lbs / kg) | 86,000 / 39,009 |
| Tender Loaded Weight (lbs / kg) | 75,000 / 34,019 |
| Total Engine and Tender Weight (lbs / kg) | 161,000 / 73,028 |
| Tender Water Capacity (gals / ML) | 3000 / 11.36 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 10 / 9.10 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 45 / 22.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 56 / 1422 |
| Boiler Pressure (psi / kPa) | 140 / 950 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 17" x 24" / 432x610 |
| Tractive Effort (lbs / kg) | 14,739 / 6685.51 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.66 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 182 - 2" / 51 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 13 / 3.96 |
| Firebox Area (sq ft / m2) | 107.80 / 10.01 |
| Grate Area (sq ft / m2) | 11.10 / 1.03 |
| Evaporative Heating Surface (sq ft / m2) | 1348 / 125.23 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 1348 / 125.23 |
| Evaporative Heating Surface/Cylinder Volume | 213.63 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 1554 |
| Same as above plus superheater percentage | 1554 |
| Same as above but substitute firebox area for grate area | 15,092 |
| Power L1 | 3908 |
| Power MT | 319.10 |