Data from T Hurry Riches and Sidney B Haslam, "Steam Motor-Car Traffic", Proceedings of the Institution of Mechanical Engineers, 1906, Parts 3-4 (October 1906), pp. 658-659, 664-666.
This was the largest steam motor coach to be built for British service and was designed by the Port Talbot's Locomotive Superintendent, A H Hertz.
Riches and Haslam noted the 6-coupled adhesive footprint and the 3-ft drivers and comment that the grade out of Port Talbot was "...extremely steep." -- a 3-mile stretch of 2 1/2% grade (1 in 40 ft). The rest of the 14-mile run to Pontyrhill had ruling grades of 1%, which of course the steam motor coach would have to scale in the other direction.
At the half-yearly meeting in 1906, Port Talbot's Colonel J R Wright claimed that the new steam rail motor coach had already given "satisfaction." It would "undoubtedly" lead to economy.
NB: Tube length is an estimate based on the calculation of tube surface area by subtracting reported firebox heating surface from reported total evaporative heating surface
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | Steam motor coach |
| Locobase ID | 12312 |
| Railroad | Port Talbot Railway & Docks |
| Country | Great Britain |
| Whyte | 0-6-0T+4 |
| Number in Class | 1 |
| Road Numbers | |
| Gauge | Std |
| Number Built | 1 |
| Builder | R W Hawthorne |
| Year | 1907 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 9.50 / 2.90 |
| Engine Wheelbase (ft / m) | 9.50 / 2.90 |
| Ratio of driving wheelbase to overall engine wheelbase | 1 |
| Overall Wheelbase (engine & tender) (ft / m) | 50 / 15.24 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | |
| Engine Weight (lbs / kg) | |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 600 / 2.27 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 36 / 914 |
| Boiler Pressure (psi / kPa) | 170 / 1170 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 12" x 16" / 305x406 |
| Tractive Effort (lbs / kg) | 9248 / 4194.83 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 69 / 6.41 |
| Grate Area (sq ft / m2) | 13.10 / 1.22 |
| Evaporative Heating Surface (sq ft / m2) | 660 / 61.34 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 660 / 61.34 |
| Evaporative Heating Surface/Cylinder Volume | 315.13 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 2227 |
| Same as above plus superheater percentage | 2227 |
| Same as above but substitute firebox area for grate area | 11,730 |
| Power L1 | 4894 |
| Power MT | |