Pennsylvania class K4s
United States 1914 425 produced
The most important express locomotive of the PRR from 1914 until it was replaced by diesel locomotives. It also survived all of its intended successors. Used the same boiler with Belpaire firebox as the L1s Mikado and influenced many other locomotives, including overseas. Number 3768 was fitted with a full streamlining by Raymond Loewy and others received partial streamlining.
Technical data
General
| Property | as built | streamlined |
|---|---|---|
| Built | 1914-1928 | 1936 |
| Manufacturers | Altoona, Baldwin | |
| Wheel arrangement | 4-6-2 (Pacific) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | as built | streamlined |
|---|---|---|
| Length | 25.45 m | |
| Wheelbase | 11.02 m | |
| Total wheelbase | 22.76 m | 26.52 m |
| Service mass | 138.1 t | 153.3 t |
| Adhesion mass | 90.5 t | 101.2 t |
| Total mass | 234.6 t | 285.8 t |
| Rigid wheelbase | 4.22 m | |
| Axle load | 29.5 t | 33.8 t |
| Water capacity | 26,498 l | |
| Fuel capacity | 14.5 t (coal) | |
Boiler
| Property | as built | streamlined |
|---|---|---|
| Grate area | 6.503 m² | |
| Firebox surface | 29.971 m² | 28.335 m² |
| Tube heating surface | 347.03 m² | 347.086 m² |
| Evaporative heating surface | 377.001 m² | 375.422 m² |
| Superheater surface | 87.608 m² | |
| Total heating surface | 464.6 m² | 463.0 m² |
Power plant
| Property | as built | streamlined |
|---|---|---|
| Driver diameter | 2,032 mm | |
| Boiler pressure | 14.1 bar | |
| Expansion type | simple expansion | |
| Cylinders | two, 686 x 711 mm | |
Power
| Property | as built | streamlined |
|---|---|---|
| Power source | steam | |
| Indicated power | 2,450 kW (3,331 PS) | |
| Top speed | 145 km/h | |
| Starting effort | 197.8 kN | |
| Estimated power | 2,431 kW (3,305 PS) | |
Calculated values
| Property | as built | streamlined |
|---|---|---|
| Factor of adhesion | 1 : 4.49 | 1 : 5.02 |
| Optimal speed | 76 km/h | |
| Power-to-weight ratio | 17.7 kW/t | 15.9 kW/t |
| Heating Surface Equivalent | 702.1 m² | 692.3 m² |
| Cylinder volume/HSE | 1 : 748.38 | 1 : 758.94 |
| Adhesive weight/Total | 1 : 1.53 | 1 : 1.52 |
| Tractive force/Heating surface | 1 : 8.89 | 1 : 8.92 |
| Grate area/Heating surface | 1 : 71.45 | 1 : 71.20 |
| Firebox/Tube surface | 1 : 11.58 | 1 : 12.25 |
| Total/Superheater | 1 : 4.30 | 1 : 4.29 |
