Canadian National class U-1-a and U-1-b
Canada 1923 37 produced
The classes U-1-a and U-1-b of the Canadian National consisted of a total of 37 Mountains with a driver diameter of 73 inches. The a and b subclasses were essentially identical, but U-1-a designated the 16 locomotives built in 1923 and U-1-b designated the 21 built in 1924. All U-1-a and some U-1-b were built with a Robinson superheater, while the rest got one of the Schmidt design. Later, more were rebuilt to the Schmidt variant. They were retired between 1951 and 1962. Today, only U-1-a is still existing and on display at Jasper, Alberta.
Technical data
General
| Property | U-1a, b Robinson superheater | U-1b Schmidt superheater |
|---|---|---|
| Built | 1923 | 1924 |
| Manufacturers | Canadian Locomotive Co. | |
| Wheel arrangement | 4-8-2 (Mountain) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | U-1a, b Robinson superheater | U-1b Schmidt superheater |
|---|---|---|
| Length | 27.54 m | |
| Wheelbase | 12.73 m | |
| Total wheelbase | 24.13 m | |
| Service mass | 160.7 t | 161.3 t |
| Adhesion mass | 106.8 t | 106 t |
| Total mass | 269.9 t | 273.9 t |
| Rigid wheelbase | 5.94 m | |
| Water capacity | 37,854 l | |
| Fuel capacity | 15.4 t (coal) | |
Boiler
| Property | U-1a, b Robinson superheater | U-1b Schmidt superheater |
|---|---|---|
| Grate area | 6.203 m² | |
| Firebox surface | 29.636 m² | |
| Tube heating surface | 346.529 m² | |
| Evaporative heating surface | 376.165 m² | |
| Superheater surface | 75.252 m² | 98.199 m² |
| Total heating surface | 451.4 m² | 474.4 m² |
Power plant
| Property | U-1a, b Robinson superheater | U-1b Schmidt superheater |
|---|---|---|
| Driver diameter | 1,854 mm | |
| Boiler pressure | 14.5 bar | |
| Expansion type | simple expansion | |
| Cylinders | two, 660 x 762 mm | |
Power
| Property | U-1a, b Robinson superheater | U-1b Schmidt superheater |
|---|---|---|
| Power source | steam | |
| Estimated power | 2,312 kW (3,143 PS) | 2,386 kW (3,244 PS) |
| Starting effort | 220.6 kN | |
Calculated values
| Property | U-1a, b Robinson superheater | U-1b Schmidt superheater |
|---|---|---|
| Factor of adhesion | 1 : 4.75 | 1 : 4.72 |
| Optimal speed | 64 km/h | 66 km/h |
| Power-to-weight ratio | 14.4 kW/t | 14.8 kW/t |
| Heating Surface Equivalent | 674.8 m² | 720.7 m² |
| Cylinder volume/HSE | 1 : 773.54 | 1 : 724.28 |
| Adhesive weight/Total | 1 : 1.51 | 1 : 1.52 |
| Tractive force/Heating surface | 1 : 10.21 | 1 : 9.71 |
| Grate area/Heating surface | 1 : 72.77 | 1 : 76.47 |
| Firebox/Tube surface | 1 : 11.69 | |
| Total/Superheater | 1 : 5.00 | 1 : 3.83 |
