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Caledonian class 721 “Dunalastair I to IV”
The increasing weight of the express trains in the 1880s and 1890s also presented the Caledonian Railway with the problem that inefficient double-headings had to be used more and more frequently. John F. McIntosh, who...
General
| Property | Caledonian class 721 “Dunalastair I to IV” Dunalastair II |
|---|---|
| Built | 1897 |
| Manufacturers | St. Rollox |
| Wheel arrangement | 4-4-0 (American) |
| Gauge | 1,435 mm (Standard gauge) |
Dimensions and weights
| Property | Caledonian class 721 “Dunalastair I to IV” Dunalastair II |
|---|---|
| Wheelbase | 7.04 m |
| Rigid wheelbase | 2.74 m |
| Service weight | 53.7 t |
| Adhesive weight | 35.2 t |
| Axle load | 18.2 t |
| Total weight | 93.4 t |
| Water capacity | 18,753 l |
| Fuel capacity | 4.6 t (coal) |
Boiler
| Property | Caledonian class 721 “Dunalastair I to IV” Dunalastair II |
|---|---|
| Grate area | 1.914 m² |
| Firebox surface | 11.028 m² |
| Tube heating surface | 128.327 m² |
| Evaporative heating surface | 139.355 m² |
| Total heating surface | 139.4 m² |
Power plant
| Property | Caledonian class 721 “Dunalastair I to IV” Dunalastair II |
|---|---|
| Driver diameter | 1,981 mm |
| Boiler pressure | 12.1 bar |
| Expansion type | simple expansion |
| Cylinders | two, 483 x 660 mm |
Power
| Property | Caledonian class 721 “Dunalastair I to IV” Dunalastair II |
|---|---|
| Power source | steam |
| Estimated power | 559 kW (760 PS) |
| Starting effort | 79.6 kN |
Calculated values
| Property | Caledonian class 721 “Dunalastair I to IV” Dunalastair II |
|---|---|
| Factor of adhesion | 1 : 4.34 |
| Optimal speed | 43 km/h |
| Power-to-weight ratio | 10.4 kW/t |
| Heating Surface Equivalent | 194.5 m² |
| Cylinder volume/HSE | 1 : 1,242.20 |
| Adhesive weight/Total | 1 : 1.52 |
| Tractive force/Heating surface | 1 : 11.93 |
| Grate area/Heating surface | 1 : 72.81 |
| Firebox/Tube surface | 1 : 11.64 |
