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Northern Pacific class Z-3
In 1913, the Northern Pacific had its first superheated Mallets made for the operation of heavy, slow freight trains over the Cascades and in the Rocky Mountains. The ten locomotives came from ALCO-Schenectady and had...
General
| Property | Northern Pacific class Z-3 1917 variant |
|---|---|
| Built | 1917, 1920 |
| Manufacturers | ALCO |
| Wheel arrangement | 2-8-8-2 (Mikado Mallet) |
| Gauge | 1,435 mm (Standard gauge) |
Dimensions and weights
| Property | Northern Pacific class Z-3 1917 variant |
|---|---|
| Wheelbase | 16.82 m |
| Rigid wheelbase | 4.57 m |
| Total wheelbase | 25.46 m |
| Service weight | 219.1 t |
| Adhesive weight | 190.3 t |
| Axle load | 25.8 t |
| Total weight | 312.3 t |
| Water capacity | 37,854 l |
| Fuel capacity | 14.5 t (coal) |
Boiler
| Property | Northern Pacific class Z-3 1917 variant |
|---|---|
| Grate area | 7.832 m² |
| Firebox surface | 34.709 m² |
| Tube heating surface | 475.98 m² |
| Evaporative heating surface | 510.689 m² |
| Superheater surface | 121.239 m² |
| Total heating surface | 631.9 m² |
Power plant
| Property | Northern Pacific class Z-3 1917 variant |
|---|---|
| Driver diameter | 1,448 mm |
| Boiler pressure | 13.8 bar |
| Expansion type | compound |
| Cylinders | four, HP: 660 x 762 mm and LP: 1,016 x 762 mm |
Power
| Property | Northern Pacific class Z-3 1917 variant |
|---|---|
| Power source | steam |
| Estimated power | 2,088 kW (2,839 PS) |
| Starting effort | 378.3 kN |
| Starting effort simple | 453.9 kN |
Calculated values
| Property | Northern Pacific class Z-3 1917 variant |
|---|---|
| Factor of adhesion | 1 : 4.93 |
| Optimal speed | 34 km/h |
| Power-to-weight ratio | 9.5 kW/t |
| Heating Surface Equivalent | 926.7 m² |
| Cylinder volume/HSE | 1 : 1,229.94 |
| Adhesive weight/Total | 1 : 1.15 |
| Tractive force/Heating surface | 1 : 12.50 |
| Grate area/Heating surface | 1 : 80.69 |
| Firebox/Tube surface | 1 : 13.71 |
| Total/Superheater | 1 : 4.21 |
