This British engine had a 4-wheel Bissel truck, in which the truck was centered by inclined lateral planes. (As the wheels entered the curve, the engine's momentum would cause it to slide up the inclined plane on the outside; the resistance increased as the curve tightened, as did the centering effect.) The sloped cylinders were mounted on extensions of the mainframe on either side of the smokebox. A narrow truck wheelbase of 40.3 inches was followed by two widely-spaced driving axles that showed much of the equalizing lever between them.
(Later events proved that 4-wheel Bissel trucks were not as successful as center-pivot designs.)
21 engines with separate tenders and 8 more tank type were built for Tudela-Bilbao. (The tank engines were later operated by Norte as 27-34.)
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | Series 27-34 |
| Locobase ID | 785 |
| Railroad | Tudela-Bilbao |
| Country | Spain |
| Whyte | 4-4-0 |
| Number in Class | 21 |
| Road Numbers | 27 |
| Gauge | 5'6" |
| Number Built | 21 |
| Builder | Beyer, Peacock |
| Year | 1863 |
| Valve Gear | |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 8 / 2.44 |
| Engine Wheelbase (ft / m) | 18 / 5.49 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.44 |
| Overall Wheelbase (engine & tender) (ft / m) | |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 58,212 / 26,405 |
| Engine Weight (lbs / kg) | 84,672 / 38,407 |
| 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) | 49 / 24.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 60 / 1524 |
| Boiler Pressure (psi / kPa) | 102.90 / 720 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 16" x 24" / 406x610 |
| Tractive Effort (lbs / kg) | 8956 / 4062.38 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 6.50 |
| 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) | 14.70 / 1.37 |
| Evaporative Heating Surface (sq ft / m2) | 943 / 87.64 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 943 / 87.64 |
| Evaporative Heating Surface/Cylinder Volume | 168.84 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 1513 |
| Same as above plus superheater percentage | 1513 |
| Same as above but substitute firebox area for grate area | |
| Power L1 | |
| Power MT | |