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The reference for locomotives and railcars

Gotthard Railway A 3/5 No. 931 to 938

Switzerland 1908 8 produced
No. 938 on the SLM data sheet SBB Historic CC BY-SA 4.0

After the first type A 3/5 express locomotives, the Gotthardbahn had Maffei develop another variant of this type in 1908. Although it was primarily intended for use on the company's valley lines, it was also intended to pull lighter trains on the mountain lines and, like its predecessors, was therefore given relatively small wheels with a diameter of 1,610 mm. Maffei used the basic construction of the Bavarian P 3/5 as a basis.

Thus, the locomotives had a bar frame and a long, narrow firebox that lay between the wheels of the second and third coupled axle. The roof of the firebox sloped backwards so that it was always sufficiently covered with water when running downhill on the 2.7 percent mountain grade. To increase efficiency, a Crawford-Clench steam dryer was used, which was replaced by the Schmidt smoke tube superheater from 1913 onwards.

The dimensions of the cylinders and parts of the valve gear corresponded to the type C 4/5 freight locomotive also supplied by Maffei in 1906 in order to reduce the number of spare parts to be kept on hand. All cylinders acted on the first coupled axle according to the Von Borries design. A piston valve was used on each side, which simultaneously controlled one high- and one low-pressure cylinder. While this arrangement was efficient, over time it resulted in damage to the valve gear.

Maffei delivered four locomotives, four more were delivered by SLM in Winterthur in the same year. On the valley lines, they could transport 350-tonne trains at one percent at 60 km/h, and at 2.7 percent on the mountain line, it was still 150 tonnes at 40 km/h. The Gotthard railway was nationalized as early as 1909, so that the locomotives were now operated by the SBB. After the Gotthard Railway was electrified, it was scrapped as early as 1925.

Sectional drawing with dimensions Die Lokomotive, June 1909

Technical data

General

Built
1908
Manufacturers
Maffei, SLM
Wheel arrangement
4-6-0 (Ten-wheeler)
Gauge
1,435 mm (Standard gauge)

Dimensions and weights

Length
17.46 m
Length loco
11.69 m
Wheelbase
8.64 m
Empty mass
70.4 t
Service mass
79.8 t
Adhesion mass
49.5 t
Total mass
117.8 t
Rigid wheelbase
3.90 m
Axle load
16.5 t
Water capacity
17,000 l
Fuel capacity
5 t (coal)

Boiler

Grate area
3.34 m²
Firebox surface
15.4 m²
Tube heating surface
173.2 m²
Evaporative heating surface
188.6 m²
Superheater surface
50.84 m²
Total heating surface
239.4 m²

Power plant

Driver diameter
1,610 mm
Boiler pressure
15 bar
Expansion type
compound
Cylinders
four, HP: 395 x 640 mm and LP: 635 x 640 mm

Power

Power source
steam
Indicated power
1,221 kW (1,660 PS)
Top speed
90 km/h
Starting effort
114.0 kN
Starting effort simple
136.8 kN

Calculated values

Factor of adhesion
1 : 4.26
Optimal speed
66 km/h
Power-to-weight ratio
15.3 kW/t
Heating Surface Equivalent
367.3 m²
Cylinder volume/HSE
1 : 978.92
Adhesive weight/Total
1 : 1.61
Tractive force/Heating surface
1 : 9.95
Grate area/Heating surface
1 : 71.69
Firebox/Tube surface
1 : 11.25
Total/Superheater
1 : 3.71
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