United Swiss Railways B 3/4
originally A3T
Switzerland 1890 15 produced
The first compound locomotives ordered by the VSB were ten express locomotives from the years 1890 to 1897. They had the wheel arrangement 2-6-0 and were designated A3T by the VSB, but are better known under their later SBB designation B 3/4.
After the first batch of ten locomotives, five more were built from 1900. Not only were the cylinders larger, but they also received a new boiler. This had higher pressure and a larger firebox at the expense of the tube heating surface. The first batch was retired between 1913 and 1924, the last disappeared in 1929.
Technical data
General
| Property | 1890 variant | 1900 variant |
|---|---|---|
| Built | 1890-1897 | 1900-1901 |
| Manufacturers | SLM | |
| Wheel arrangement | 2-6-0 (Mogul) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | 1890 variant | 1900 variant |
|---|---|---|
| Length | 13.38 m | |
| Wheelbase | 6.00 m | |
| Total mass | 74.6 t | |
| Rigid wheelbase | 3.52 m | |
| Axle load | 12.7 t | 12.8 t |
| Water capacity | 9,600 l | 10,600 l |
| Fuel capacity | 4 t (coal) | |
Boiler
| Property | 1890 variant | 1900 variant |
|---|---|---|
| Grate area | 1.7 m² | 1.9 m² |
| Firebox surface | 7.7 m² | 9.2 m² |
| Tube heating surface | 130.9 m² | 123 m² |
| Evaporative heating surface | 138.6 m² | 132.2 m² |
| Total heating surface | 138.6 m² | 132.2 m² |
Power plant
| Property | 1890 variant | 1900 variant |
|---|---|---|
| Driver diameter | 1,590 mm | |
| Boiler pressure | 12 bar | 13 bar |
| Expansion type | compound | |
| Cylinders | two, HP: 450 x 650 mm and LP: 640 x 650 mm | two, HP: 465 x 650 mm and LP: 680 x 650 mm |
Power
| Property | 1890 variant | 1900 variant |
|---|---|---|
| Power source | steam | |
| Indicated power | 515 kW (700 PS) | |
| Top speed | 75 km/h | |
| Starting effort | 56.5 kN | 66.6 kN |
| Starting effort simple | 67.8 kN | 79.9 kN |
Calculated values
| Property | 1890 variant | 1900 variant |
|---|---|---|
| Optimal speed | 56 km/h | 47 km/h |
| Power-to-weight ratio | 6.9 kW/t | |
| Heating Surface Equivalent | 177.1 m² | 178.2 m² |
| Cylinder volume/HSE | 1 : 1,174.08 | 1 : 1,281.79 |
| Tractive force/Heating surface | 1 : 8.51 | 1 : 10.51 |
| Grate area/Heating surface | 1 : 81.53 | 1 : 69.58 |
| Firebox/Tube surface | 1 : 17.00 | 1 : 13.37 |
