Data from "Locomotivas de Vapor de Via Larga"p. 24, posted Posted by Guarda Freio at 18:01, 23 September 2018, at [], last accessed 25 January 2026. Works numbers were 3239-3246 in 1890.
The Manchester builder joined the trend that encouraged the adoption of compound working. They adopted the cross-compound favored by many for its relative simplicity. Steam entered the high-pressure cylinderdirectly. At the end of the stroke, a valve opened to send the exhaust to the larger low-pressure cylinder.
The Portugues octet staked a claim for its use of a compound system and used it on a high-wheeling express American-type Eight-wheeler.
According to the diagram used in this entry, the CP's Lisbon shops began modiifying several of the class beginning in 1908 and 1912-1914. Locobase supposes they switched to a two-cylinder simple setup, but cannot confirm.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 91 |
| Locobase ID | 21317 |
| Railroad | Caminho |
| Country | Portugal |
| Whyte | 4-4-0 |
| Number in Class | 8 |
| Road Numbers | 91-98 |
| Gauge | Via Larga |
| Number Built | 8 |
| Builder | Beyer, Peacock |
| Year | 1891 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 8.50 / 2.59 |
| Engine Wheelbase (ft / m) | 22.08 / 6.73 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.38 |
| Overall Wheelbase (engine & tender) (ft / m) | 41.16 / 12.55 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 34,282 / 15,550 |
| Weight on Drivers (lbs / kg) | 66,580 / 30,200 |
| Engine Weight (lbs / kg) | 111,113 / 50,400 |
| Tender Loaded Weight (lbs / kg) | 75,618 / 34,300 |
| Total Engine and Tender Weight (lbs / kg) | 186,731 / 84,700 |
| Tender Water Capacity (gals / ML) | 3696 / 14 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 4.40 / 4 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 55 / 27.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 78.70 / 2000 |
| Boiler Pressure (psi / kPa) | 201.30 / 1370 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 19.25" x 25.98" / 489x660 (1) |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 27.99" x 25.98" / 711x660 (1) |
| Tractive Effort (lbs / kg) | 14,210 / 6445.56 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.69 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 123 - 2.756" / 70 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 10.40 / 3.17 |
| Firebox Area (sq ft / m2) | 142.08 / 13.20 |
| Grate Area (sq ft / m2) | 22.50 / 2.09 |
| Evaporative Heating Surface (sq ft / m2) | 1065 / 98.94 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 1065 / 98.94 |
| Evaporative Heating Surface/Cylinder Volume | 243.39 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 4529 |
| Same as above plus superheater percentage | 4529 |
| Same as above but substitute firebox area for grate area | 28,601 |
| Power L1 | 5067 |
| Power MT | 335.56 |