Atlanta & West Point class F
The Atlanta & West Point operated a total of six Mikados of different design, which were designated class F. The first two, numbered 400 and 401, were built in 1918 by Lima. They were of the Harriman Common Standard Mikado design and were built together with two for the Western Railway of Alabama. Three more were built by Lima between 1923 and 1925 which received the numbers 425 to 427. But these were copies of the USRA Light Mikado and again, the Western Railway of Alabama got four from the same batch.
No. 430, built by Baldwin in 1944, was an updated USRA Heavy Mikado copy. Together with another locomotive for the Western Railway of Alabama, they were among the last Mikados built for a US railroad. The total surface in the firebox was much bigger with 57 square feet in the combustion chamber, two thermic syphons of 40 square feet each and 14 square feet in arch tubes. 400 and 401 were retired in 1951 and the others followed between 1952 and 1954.
Technical data
General
| Property | 400, 401 | 425-427 | 430 |
|---|---|---|---|
| Built | 1918 | 1923-1925 | 1944 |
| Manufacturers | Lima | Baldwin | |
| Wheel arrangement | 2-8-2 (Mikado) | ||
| Gauge | 1,435 mm (Standard gauge) | ||
Dimensions and weights
| Property | 400, 401 | 425-427 | 430 |
|---|---|---|---|
| Wheelbase | 10.72 m | 11.25 m | |
| Total wheelbase | 22.02 m | 21.76 m | 24.85 m |
| Service mass | 128.4 t | 132.4 t | 151.4 t |
| Adhesion mass | 97.1 t | 102.3 t | 117.3 t |
| Total mass | 221.6 t | 214.9 t | 302.9 t |
| Rigid wheelbase | 5.03 m | 5.11 m | |
| Axle load | 24.9 t | 25.6 t | 29.3 t |
| Water capacity | 41,640 l | 37,854 l | 68,137 l |
| Fuel capacity | 13.6 t (coal) | 14.5 t (coal) | 16.3 t (coal) |
Boiler
| Property | 400, 401 | 425-427 | 430 |
|---|---|---|---|
| Grate area | 6.54 m² | 6.197 m² | 6.531 m² |
| Firebox surface | 21.832 m² | 26.013 m² | 34.932 m² |
| Tube heating surface | 370.312 m² | 324.882 m² | 336.681 m² |
| Evaporative heating surface | 392.144 m² | 350.895 m² | 371.613 m² |
| Superheater surface | 80.361 m² | 81.941 m² | 118.544 m² |
| Total heating surface | 472.5 m² | 432.8 m² | 490.2 m² |
Power plant
| Property | 400, 401 | 425-427 | 430 |
|---|---|---|---|
| Driver diameter | 1,600 mm | ||
| Boiler pressure | 12.4 bar | 13.8 bar | |
| Expansion type | simple expansion | ||
| Cylinders | two, 686 x 762 mm | two, 660 x 762 mm | two, 686 x 813 mm |
Power
| Property | 400, 401 | 425-427 | 430 |
|---|---|---|---|
| Power source | steam | ||
| Estimated power | 2,088 kW (2,839 PS) | 2,200 kW (2,991 PS) | 2,535 kW (3,447 PS) |
| Starting effort | 236.3 kN | 243.4 kN | 280.0 kN |
Calculated values
| Property | 400, 401 | 425-427 | 430 |
|---|---|---|---|
| Factor of adhesion | 1 : 4.03 | 1 : 4.12 | 1 : 4.11 |
| Optimal speed | 55 km/h | ||
| Power-to-weight ratio | 16.3 kW/t | 16.6 kW/t | 16.7 kW/t |
| Heating Surface Equivalent | 662.0 m² | 644.8 m² | 783.4 m² |
| Cylinder volume/HSE | 1 : 850.34 | 1 : 809.54 | 1 : 766.54 |
| Adhesive weight/Total | 1 : 1.32 | 1 : 1.29 | |
| Tractive force/Heating surface | 1 : 10.44 | 1 : 11.75 | 1 : 11.93 |
| Grate area/Heating surface | 1 : 72.25 | 1 : 69.85 | 1 : 75.05 |
| Firebox/Tube surface | 1 : 16.96 | 1 : 12.49 | 1 : 9.64 |
| Total/Superheater | 1 : 4.88 | 1 : 4.28 | 1 : 3.13 |
