Data from "Locomotive Engines at the Paris Exhibition", The Artizan, Vol II, 4th Series, #2 (11 February 1868), p. 26, corrected by Ernest Taillard, Exposition Universelle de Paris de 1867-Chemins de Fer-Les Locomotives et le Materiel de Transport, 1ie Volume (Paris: Dunod, 1867), pp.12-21
The report of this locomotive's appearance at the 1867 Paris Exhibition contains one of the earliest detailed descriptions of Walschaert's outside valve gear. The design had a Belpaire firebox. Its water tanks and coal bunker straddled the coupled wheebase to take full advantage of the weight of the fuel and water even as it was drawn off during operation.
It was described as "somewhat similar" to engines used on the Alar del Rey and Santander railways in northern Spain. The Vaessen bogie had a good deal of lateral travel on inclined planes even as the rotational pivot remained stationary. the movement was lever-driven and all of the mechanism was displayed outside. In addition, one of the coupled axles enjoyed lateral play as well.
NB: Locobase uses the singular version for the valve gear and bases that choice on the 1848 Rapports de jury et documents de l'Exposition de l'industrie belger en 1847 (Bruxelles: M. Hayez, Imprimeur de L'Academie Royale, 1848), p. 175, that clearly identifies the railway engineer as "M. Walschaert, Egide". His silver medals were awarded for a valve gear design employed on an steam engine for a yacht.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | Vaessen |
| Locobase ID | 11157 |
| Railroad | |
| Country | Belgium |
| Whyte | 4-6-0T |
| Number in Class | |
| Road Numbers | |
| Gauge | Std |
| Number Built | |
| Builder | SA Saint Leonard |
| Year | 1867 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 9.84 / 3 |
| Engine Wheelbase (ft / m) | 19.52 / 5.95 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.50 |
| Overall Wheelbase (engine & tender) (ft / m) | 19.52 / 5.95 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 28,448 / 12,904 |
| Weight on Drivers (lbs / kg) | 84,223 / 38,203 |
| Engine Weight (lbs / kg) | 108,192 / 49,075 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 1716 / 6.50 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 2.80 / 3 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 47 / 23.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 51.20 / 1300 |
| Boiler Pressure (psi / kPa) | 130.50 / 900 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 18.11" x 23.62" / 460x600 |
| Tractive Effort (lbs / kg) | 16,783 / 7612.65 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 5.02 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 193 - 1.969" / 50 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 12.14 / 3.70 |
| Firebox Area (sq ft / m2) | 97.92 / 9.10 |
| Grate Area (sq ft / m2) | 21.74 / 2.02 |
| Evaporative Heating Surface (sq ft / m2) | 1293 / 120.17 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 1293 / 120.17 |
| Evaporative Heating Surface/Cylinder Volume | 183.61 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 2837 |
| Same as above plus superheater percentage | 2837 |
| Same as above but substitute firebox area for grate area | 12,779 |
| Power L1 | 2819 |
| Power MT | 221.37 |