Great Northern (US) class L-3
Great Northern (US) classes M-1 and M-2
In order to prevent individual chassis groups from slipping on slow freight trains, the Great Northern ordered a Mallet with unequal axle distribution. The front group consisted of a leading axle and three driving axles, while the rear group consisted of four driving axles. After ten locomotives from 1909, another 25 followed, which had a larger firebox and superheater. Under the new scheme, they were designated class M-1.
They were converted to simple expansion to save complexity from 1926 and were designated class M-2. The rear cylinders remained slightly larger in order to be able to convert enough power for the additional driving axle. The existing feedwater heater was also removed. The locomotives had a choppy running that made speeds over 25 mph (40 km/h) difficult to run. 22 were scrapped from 1929 and their parts used for new O-7 class Mikados, while the remaining 13 partially survived until 1954.
Technical data
General
| Property | first series | second series | rebuilt M-2 |
|---|---|---|---|
| Built | 1909 | 1910 | 1926-1928 |
| Manufacturers | Baldwin | Great Northern | |
| Wheel arrangement | 2-6-8-0 | ||
| Gauge | 1,435 mm (Standard gauge) | ||
Dimensions and weights
| Property | first series | second series | rebuilt M-2 |
|---|---|---|---|
| Wheelbase | 13.39 m | ||
| Total wheelbase | 23.23 m | 26.04 m | |
| Service mass | 167.2 t | 182.8 t | |
| Adhesion mass | 158.8 t | 174.2 t | |
| Total mass | 237.1 t | 264.4 t | |
| Rigid wheelbase | 3.81 m | 4.57 m | |
| Axle load | 23.3 t | 22.7 t | 25.4 t |
| Water capacity | 30,283 l | 37,854 l | |
| Fuel capacity | 11.8 t (coal) | 17,034 l (oil) | |
Boiler
| Property | first series | second series | rebuilt M-2 |
|---|---|---|---|
| Grate area | 7.246 m² | ||
| Firebox surface | 20.903 m² | 23.969 m² | |
| Tube heating surface | 447.31 m² | 462.843 m² | |
| Evaporative heating surface | 468.213 m² | 486.812 m² | |
| Superheater surface | 44.594 m² | 53.791 m² | 138.426 m² |
| Total heating surface | 512.8 m² | 522.0 m² | 625.2 m² |
Power plant
| Property | first series | second series | rebuilt M-2 |
|---|---|---|---|
| Driver diameter | 1,397 mm | ||
| Boiler pressure | 13.8 bar | 14.5 bar | |
| Expansion type | compound | simple expansion | |
| Cylinders | four, HP: 584 x 813 mm and LP: 889 x 813 mm | four, 559 x 813 mm | |
Power
| Property | first series | second series | rebuilt M-2 |
|---|---|---|---|
| Power source | steam | ||
| Estimated power | 1,864 kW (2,534 PS) | 2,013 kW (2,737 PS) | 2,386 kW (3,244 PS) |
| Starting effort | 325.1 kN | 447.2 kN | |
| Starting effort simple | 390.1 kN | ||
Calculated values
| Property | first series | second series | rebuilt M-2 |
|---|---|---|---|
| Factor of adhesion | 1 : 4.79 | 1 : 3.82 | |
| Optimal speed | 35 km/h | 39 km/h | 32 km/h |
| Power-to-weight ratio | 11.1 kW/t | 12.0 kW/t | 13.1 kW/t |
| Heating Surface Equivalent | 661.9 m² | 680.3 m² | 883.5 m² |
| Cylinder volume/HSE | 1 : 1,420.51 | 1 : 1,382.10 | 1 : 902.48 |
| Adhesive weight/Total | 1 : 1.05 | ||
| Tractive force/Heating surface | 1 : 13.24 | 1 : 13.01 | 1 : 14.94 |
| Grate area/Heating surface | 1 : 70.77 | 1 : 72.04 | 1 : 86.29 |
| Firebox/Tube surface | 1 : 21.40 | 1 : 19.31 | |
| Total/Superheater | 1 : 10.50 | 1 : 8.70 | 1 : 3.52 |
