Data from "Compound Locomotive for a Narrow Gauge Tramway", Engineering News (1 September 1888), p 167. See also "The Laon Steep-Gradient Railroad", The Railroad and Engineering Journal, Volume LXIII, No 5 (May 1889), p. 247.
This was one of Anatole Mallet's early designs that included the main ingredients that would characterize the Mallet design throughout the steam era. The rear engine unit was fixed and had HP cylinders. The front engine unit was driven by the LP cylinders that took steam from the HP exhaust. It was free to traverse (over a limited range) and thus negotiate the tight curve radii of small railways. A driver could start the locomotive by admitting live steam to all four cylinders if necessary.
The REJ report notes that the tramway was called upon to scale a difference of 100 metres (328 feet) in 1 3/4 miles, which necessitated tight curves and very steep grades. The rails themselves weighed a scant 19.5 lb/yard (9.75 kg/metre). The Engineering News account includes details of the engine and a detailed engraving. The cars it hauled had two 4-wheel trucks. They held 24 seated passengers and 8 standees.
Laon would later operate a rack railroad.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | unknown |
| Locobase ID | 13492 |
| Railroad | Laon Tramway |
| Country | France |
| Whyte | 0-4-4-0T |
| Number in Class | |
| Road Numbers | |
| Gauge | 60 cm |
| Number Built | |
| Builder | |
| Year | 1888 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 5.58 / 1.70 |
| Engine Wheelbase (ft / m) | 9.19 / 2.80 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.61 |
| Overall Wheelbase (engine & tender) (ft / m) | 9.19 / 2.80 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 6301 / 2858 |
| Weight on Drivers (lbs / kg) | 25,201 / 11,431 |
| Engine Weight (lbs / kg) | 25,201 / 11,431 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 11 / 5.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 23.60 / 600 |
| Boiler Pressure (psi / kPa) | 174 / 1200 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 6.69" x 10.24" / 170x260 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 10" x 10.24" / 254x260 |
| Tractive Effort (lbs / kg) | 3968 / 1799.86 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 6.35 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | |
| Grate Area (sq ft / m2) | 4.52 / 0.42 |
| Evaporative Heating Surface (sq ft / m2) | 254 / 23.60 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 254 / 23.60 |
| Evaporative Heating Surface/Cylinder Volume | 609.68 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 786 |
| Same as above plus superheater percentage | 786 |
| Same as above but substitute firebox area for grate area | |
| Power L1 | |
| Power MT | |