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Italian State Railway class 691
The gruppo 691 was created by rebuilding all 33 locomotives of the gruppo 690. Although the 690 had four large cylinders, the boiler could not keep up with their steam demand at speed. So they received the boiler of t...
General
| Property | Italian State Railway class 691Remove |
|---|---|
| Built | 1928-1934 |
| Manufacturers | FS, Breda |
| Wheel arrangement | 4-6-2 (Pacific) |
| Gauge | 1,435 mm (Standard gauge) |
Dimensions and weights
| Property | Italian State Railway class 691Remove |
|---|---|
| Length | 22.64 m |
| Length loco | 13.79 m |
| Wheelbase | 10.95 m |
| Rigid wheelbase | 4.30 m |
| Total wheelbase | 19.84 m |
| Empty weight | 81 t |
| Service weight | 90.5 t |
| Adhesive weight | 54 t |
| Axle load | 18 t |
| Total weight | 150 t |
| Water capacity | 29,000 l |
| Fuel capacity | 4.7 t (coal) |
Boiler
| Property | Italian State Railway class 691Remove |
|---|---|
| Grate area | 4.3 m² |
| Firebox surface | 17 m² |
| Tube heating surface | 220 m² |
| Evaporative heating surface | 237 m² |
| Superheater surface | 67 m² |
| Total heating surface | 304.0 m² |
Power plant
| Property | Italian State Railway class 691Remove |
|---|---|
| Driver diameter | 2,030 mm |
| Boiler pressure | 16 bar |
| Expansion type | simple expansion |
| Cylinders | four, 450 x 680 mm |
Power
| Property | Italian State Railway class 691Remove |
|---|---|
| Power source | steam |
| Indicated power | 1,290 kW (1,754 PS) |
| Top speed | 130 km/h |
| Starting effort | 184.5 kN |
Calculated values
| Property | Italian State Railway class 691Remove |
|---|---|
| Factor of adhesion | 1 : 2.87 |
| Optimal speed | 43 km/h |
| Power-to-weight ratio | 14.3 kW/t |
| Heating Surface Equivalent | 456.0 m² |
| Cylinder volume/HSE | 1 : 948.68 |
| Adhesive weight/Total | 1 : 1.68 |
| Tractive force/Heating surface | 1 : 12.68 |
| Grate area/Heating surface | 1 : 70.70 |
| Firebox/Tube surface | 1 : 12.94 |
| Total/Superheater | 1 : 3.54 |
