Data from "SZD-Baureihe P38" in Wikipedia at [], last accessed 3 November 2019.
The only Mallets built for either Russian or Soviet railroads. Two engines built. A relatively light and late articulated that had high maintenance costs and was difficult to work in cold weather. A photo shows that above the usual array of drivers and valve gear and pistons and whatnot, the boiler had a streamlined nose much like a 1950s automobile from a Detroit design studio.
NB: The driver wheelbase given in Locobase is correct. Five of the six intervals between axles measured 1,625 mm (5 ft 4 in). The rear engine's wheelbase was longer than the front because of a 175 mm greater distance (1,800 mm/5 ft 10 3/4 in total ) between the third and fourth axles.
Despite the shortcomings, these big articulateds may have served the Soviet State for decades except for a decision at the 20th Party Congress of the CPSU (Communist Party of the Soviet Union) in February 1956. A defensible argument for ending steam locomotive production in favor of widespread electrification meant all design efforts would stop.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | P38 |
| Locobase ID | 733 |
| Railroad | Soviet State |
| Country | Soviet Union |
| Whyte | 2-8-8-4 |
| Number in Class | 4 |
| Road Numbers | P38.0001-P38.0004 |
| Gauge | 5' |
| Number Built | 4 |
| Builder | Putilov |
| Year | 1954 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 32.55 / 9.92 |
| Engine Wheelbase (ft / m) | 63.88 / 19.47 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.51 |
| Overall Wheelbase (engine & tender) (ft / m) | |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 45,107 / 20,460 |
| Weight on Drivers (lbs / kg) | 355,782 / 161,380 |
| Engine Weight (lbs / kg) | 470,995 / 213,640 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 15,840 / 60 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 38.50 / 35 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 74 / 37 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 59.10 / 1501 |
| Boiler Pressure (psi / kPa) | 213.20 / 1470 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 22.64" x 31.5" / 575x800 (4) |
| Tractive Effort (lbs / kg) | 99,018 / 44913.86 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.59 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 20.34 / 6.20 |
| Firebox Area (sq ft / m2) | |
| Grate Area (sq ft / m2) | 115.17 / 10.70 |
| Evaporative Heating Surface (sq ft / m2) | 4266 / 396.32 |
| Superheating Surface (sq ft / m2) | 2548 / 236.71 |
| Combined Heating Surface (sq ft / m2) | 6814 / 633.03 |
| Evaporative Heating Surface/Cylinder Volume | 145.33 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 24,554 |
| Same as above plus superheater percentage | 33,639 |
| Same as above but substitute firebox area for grate area | |
| Power L1 | |
| Power MT | |