The B&E broke off from the Great Western in 1849. When it came time to order express engines for the "Flying Dutchman," then the fastest service in the world, the B&E's locomotive superintendent ordered these unparalleled engines. They had the tallest drivers ever in regular service on a steam engine; moreover, they were flangeless.
Remarkably for such an unusual arrangement (unique as far as Locobase knows), these engines gave very good service. Hollingsworth (1982) notes that when they were rebuilt 14 years after service entry, the original plans for these "9-footers" were sufficient. Beginning in 1876, however, the Great Western rebuilt these locomotives as 4-2-2s.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | Pearson |
| Locobase ID | 2544 |
| Railroad | Bristol & Exeter |
| Country | Great Britain |
| Whyte | 4-2-4 |
| Number in Class | 8 |
| Road Numbers | 39-46 / 2001-2004 |
| Gauge | 7' |
| Number Built | 8 |
| Builder | Rothwell & Bolton |
| Year | 1853 |
| Valve Gear | |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | |
| Engine Wheelbase (ft / m) | |
| Ratio of driving wheelbase to overall engine wheelbase | |
| Overall Wheelbase (engine & tender) (ft / m) | 30.75 / 9.37 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 41,500 / 18,824 |
| Weight on Drivers (lbs / kg) | 41,500 / 18,824 |
| Engine Weight (lbs / kg) | 112,000 / 50,802 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 1720 / 6.52 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 2.20 / 2 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 69 / 34.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 106 / 2692 |
| Boiler Pressure (psi / kPa) | 120 / 830 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 18" x 24" / 457x610 |
| Tractive Effort (lbs / kg) | 7483 / 3394.24 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 5.55 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 180 - 1.313" / 33 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 11 / 3.35 |
| Firebox Area (sq ft / m2) | 146 / 13.57 |
| Grate Area (sq ft / m2) | 23.10 / 2.15 |
| Evaporative Heating Surface (sq ft / m2) | 1235 / 114.78 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 1235 / 114.78 |
| Evaporative Heating Surface/Cylinder Volume | 174.72 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 2772 |
| Same as above plus superheater percentage | 2772 |
| Same as above but substitute firebox area for grate area | 17,520 |
| Power L1 | 5893 |
| Power MT | 313.06 |