US Railroad Administration Heavy Mountain
Chesapeake & Ohio class J-2 and Norfolk & Western class K2
One of the USRA standard types intended for lighter, fast freight trains was the Heavy Mountain. Compared to the Light Mountain, it had the same wheel diameter and boiler pressure, but a cylinder diameter increased by one inch. Compared to the Mikados, which were also intended for lighter freight trains, they had a driver diameter that was seven inches larger and were therefore designed for higher speeds.
Only 15 of the Heavy Mountain were built, five of which were built as the class J-2 of the Chesapeake & Ohio and ten as the class K2 of the Norfolk & Western. A total of 37 copies were built in 1923 and 1926, differing in details from the USRA standard design. The Norfolk & Western's twelve K-2a already had higher boiler pressure and larger drivers.
Technical data
General
| Property | Chesapeake & Ohio | Norfolk & Western K-2a |
|---|---|---|
| Built | 1918 | 1919 |
| Manufacturers | ALCO, Baldwin | |
| Wheel arrangement | 4-8-2 (Mountain) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | Chesapeake & Ohio | Norfolk & Western K-2a |
|---|---|---|
| Wheelbase | 12.19 m | |
| Total wheelbase | 23.08 m | |
| Service mass | 159.9 t | 163 t |
| Adhesion mass | 110.2 t | 112.6 t |
| Total mass | 248 t | 334.8 t |
| Rigid wheelbase | 5.56 m | |
| Axle load | 27.6 t | 28.1 t |
| Water capacity | 37,854 l | |
| Fuel capacity | 14.5 t (coal) | |
Boiler
| Property | Chesapeake & Ohio | Norfolk & Western K-2a |
|---|---|---|
| Grate area | 7.089 m² | |
| Firebox surface | 34.653 m² | 34.281 m² |
| Tube heating surface | 398.833 m² | 380.996 m² |
| Evaporative heating surface | 433.486 m² | 415.277 m² |
| Superheater surface | 100.8 m² | |
| Total heating surface | 534.3 m² | 516.1 m² |
Power plant
| Property | Chesapeake & Ohio | Norfolk & Western K-2a |
|---|---|---|
| Driver diameter | 1,753 mm | 1,778 mm |
| Boiler pressure | 13.8 bar | 15.2 bar |
| Expansion type | simple expansion | |
| Cylinders | two, 711 x 762 mm | |
Power
| Property | Chesapeake & Ohio | Norfolk & Western K-2a |
|---|---|---|
| Power source | steam | |
| Estimated power | 2,535 kW (3,447 PS) | 2,629 kW (3,574 PS) |
| Starting effort | 257.8 kN | 279.5 kN |
Calculated values
| Property | Chesapeake & Ohio | Norfolk & Western K-2a |
|---|---|---|
| Factor of adhesion | 1 : 4.19 | 1 : 3.95 |
| Optimal speed | 60 km/h | 58 km/h |
| Power-to-weight ratio | 15.9 kW/t | 16.1 kW/t |
| Heating Surface Equivalent | 808.4 m² | 788.3 m² |
| Cylinder volume/HSE | 1 : 748.96 | 1 : 768.03 |
| Adhesive weight/Total | 1 : 1.45 | |
| Tractive force/Heating surface | 1 : 10.08 | 1 : 11.31 |
| Grate area/Heating surface | 1 : 75.37 | 1 : 72.80 |
| Firebox/Tube surface | 1 : 11.51 | 1 : 11.11 |
| Total/Superheater | 1 : 4.30 | 1 : 4.12 |
