NOB A 2/4 (Winterthur) - NOB A 2/4 (Winterthur)

NOB A 2/4
Locomotive A 2/4 Number 116
Locomotive A 2/4 Number 116
Numbering: NOB 101-121
SBB 151-200
Number: 50
Manufacturer: SLM
Year of construction (s): 1898–1906
Ausmusterung: 1917–1925
Axis formula : 2'B
Type : Two-cylinder compound
Gauge : 1435 mm (Normalspur)
Length over buffers: 15820 mm
Fixed wheelbase: 2600 mm
Total wheelbase: 7200 mm
Learning Mass: 27.3 t (from 176, 29.2 t)
Service mass with tender: 81.3 t (from 176, 84.5 t)
Friction mass: 31.7 t (from 176, 13.8 t)
Driving wheel diameter: 1830 mm
Number of cylinders: 2
HD cylinder diameter: 460 mm
LP cylinder diameter: 680 mm
Piston stroke: 660 mm
Boiler overpressure: 13 Atm.
Number of heating pipes: 220
Heating pipe length: 3800 mm
Grate area: 2,2 m²
Radiant heating surface: 10,5 m²
Evaporation heating surface: 128,6 m²
Water supply: 12 m³ (ab 176, 13.8 m³)
Fuel supply: 6 t (coal)

The Swiss Northeast Railway ( NOB ) acquired A 2/4 type A 2/4 steam locomotives with a tender for express train service from 1895 . 25 locomotives were ordered by the NOB. Because the SBB ordered a further 25 machines, 50 identical locomotives of this type were ultimately delivered by SLM .


It was a two-cylinder compound machine. It was the only machine at the NOB to have an internal engine, which was expected to be smoother. The development was able to fall back on the experiences made with the JS A 2/4 (1892) and SCB A 2/4 (1997) as well as their own B 3/4 (1892). It was decided that, as with the JS, a two-cylinder engine would be sufficient and, in contrast to the SCB, a four-cylinder engine was dispensed with.

The boiler was 2430 mm above the top of the rail. The first 40 locomotives did not have a steam dome, but a steam collecting pipe. The boilers of numbers 191-200, however, were constructed a little differently. They received a steam dome and normal SBB slide regulators. The safety valve was mounted on the rear boiler. The first machines received a Ramsbottom safety valve, from the 181 a Popp safety valve was installed instead. The slide regulator, which was located in the smoke chamber, could be operated from the rear wall of the boiler using an offset lever. The inflow and overflow pipes were also built into the smoke chamber, which explains their length of 1400 mm. The last 25 locomotives that the SBB had already ordered were equipped with a tilting grate.

The inner frame was 25 mm thick and had to be pulled 65 mm apart in the area of ​​the cylinders, as the boiler pressure of 13 atm did not allow smaller cylinders at the desired output. Smaller cylinders would have required a higher boiler pressure of 15 to 16 atm, but the NOB did not want to get involved.

Express train locomotive A 2/4 No. 193 of the SBB built according to the plans of the NOB in 1906
Data sheet of the penultimate series A 2/4.

The leaf springs of the drive axles were suspended under the axle bearings and are supported on evolutionary springs . They were connected to one another inside with longitudinal levers. The axles of the bogie had independent leaf springs over the axle bearings. The bogie with a 2200 mm wheelbase could be moved sideways. It was pressed into the central position with the help of two counter-tensioned leaf springs.

The cylinders were inclined at a ratio of 1:35. The drive rods were connected to the first cranked coupling axle. The piston rods were passed forward. The outside of the coupling rods was offset by 180 ° to the inner drive rod. The Walschaerts control was inside, but it was driven by counter cranks that were attached to the outside of the crank pin. The movement was transmitted via transverse waves. The steam supply to the Trickkanal flat slide is via the outer edge. When the controls were in the forward position, the rocker blocks were on top. A starting aid based on the Von-Bories-Winterthur principle enabled the low-pressure cylinder and the high-pressure cylinder to get steam out of the boiler if the crank was in an unfavorable position.

The three-axle tender with an outer frame also differed slightly. From no. 176 the water tank was enlarged from 12 m³ to 13.8 m³ and changed again for the last 10 machines.

The Westinghouse brake acted with eight brake blocks on the coupling axles, and on the last 10 pieces also on the axles of the bogie. In addition, the tender's 12 brake blocks were used, on which the Westinghouse and spindle hand brakes worked.

The speedometer was of the Klose design. In addition, all machines had a facility for steam heating the passenger cars.

Serie NOB
SBB from
Construction year Manufacturer Discarded Remarks
A 2/4 101–
151 1154–
1898 SLM 1917
A 2/4 104–
1899 SLM 1925 (156, 157; † 1917)
(158, 160–162; † 1924)
A 2/4 113–
1900 SLM 1925
A 2/4 117–
1901 SLM 1925 (168; † 1917)
(170; † 1924)
A 2/4 121–1251 171–
1902 SLM 1925 (174; † 1924)
A 2/4 176–
1903 SLM 1925
A 2/4 181–
1904 SLM 1925 (188; † 1924)
A 2/4 191–
1906 SLM 1925 (193, 199; † 1924)

1 Ordered by the NOB, but delivered to SBB.


Under the management of the SBB, the numbers 151–162 and 191–200 were assigned to District IV and the Rorschach workshop for maintenance purposes, the remaining locomotives to District III and the Zurich workshop.

The usual load on the plain was 300–600 tons, on a 12 per mille gradient 200–240 tons. It was considered the more economical locomotive of the three A-2/4 types for the SBB.


The locomotive number 116 was shown at the World Exhibition in Paris in 1900.


  • Alfred Moser: The steam operation of the Swiss railways 1847-1966 . 4th updated edition, Birkhäuser, Stuttgart 1967, pp. 73 ff.