Meyer's valve gear was the main feature on this successful design. Using a by-now standard gab rod arrangement, Meyer added an auxiliary valve that allowed the fixed cutoff inherent in the gab rod arrangement to be varied by the driver. Reder (1974, pl 54) has an excellent illustration.
The benefit lay in reduced fuel consumption. Trials saw L'Esperance consume only 13.3 lb of coke fuel per train mile, at least 27% less than competitive engines. He notes that the railroad was sufficiently pleased to order Le Succes as a sister and Meyer himself built the Mulhouse at his own expense.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | L'Esperance |
| Locobase ID | 4817 |
| Railroad | CF de Alsace |
| Country | France |
| Whyte | 2-2-2 |
| Number in Class | 3 |
| Road Numbers | |
| Gauge | Std |
| Number Built | 3 |
| Builder | Jean-Jacques Meyer |
| Year | 1842 |
| Valve Gear | Meyer |
| 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) | |
| 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) | |
| 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) | 72 / 1829 |
| Boiler Pressure (psi / kPa) | 75.40 / 520 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 15" x 17.99" / 381x457 |
| Tractive Effort (lbs / kg) | 3603 / 1634.30 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 125 - 1.811" / 46 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 8.53 / 2.60 |
| Firebox Area (sq ft / m2) | 53.37 / 4.96 |
| Grate Area (sq ft / m2) | 8.93 / 0.83 |
| Evaporative Heating Surface (sq ft / m2) | 501 / 46.54 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 501 / 46.54 |
| Evaporative Heating Surface/Cylinder Volume | 136.16 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 673 |
| Same as above plus superheater percentage | 673 |
| Same as above but substitute firebox area for grate area | 4024 |
| Power L1 | 1888 |
| Power MT | |