GB A 3/5 201–230 - GB A 3/5 201–230

GB A 3/5 201–230
Type designation: A 3/5
Three-cylinder compound engine No. 201 Four-cylinder compound locomotive No. 202-230
GB A 3-5 215.jpg
Numbering: 201 202 203–230
Number: 1 1 28
Manufacturer: SLM
Year of construction (s): 1894 1894 1897–1905
Ausmusterung: 1923–1927
Type : 2'C n3v 2’C n4v
Gauge : 1435 mm (Normalspur)
Length over buffers: 16320 mm 16700–16710 mm[1]
Fixed wheelbase: 3520 mm 3830 mm
Learning Mass: [1] 59,5 t 61,0 t 57,3 t – 58,3 t
Service mass: [1] 66,5 t 68,0 t 63,7 t – 65,0 t
Friction mass: [1] 45,0 t 45,9 t – 46,8 t
Wheel set mass : 15,0 t 15,6 t
Top speed: 90 km / h
Driving wheel diameter: 1610 mm[1]
Number of cylinders: 3 4
LP cylinder diameter: 480 mm[2] 530 mm[2] 570–600 mm[1]
HD cylinder diameter: 440 mm[2] 350 mm[2] 370 mm[1]
Piston stroke: 600 mm
Boiler overpressure: 14 atm 15 atm
Indexed performance : 1400 PS
Tender: 3-achsig
Water supply: [1] 14,4 m³ 17,0 m³
Fuel supply: 5 t
Brake: Double Westinghouse brake
Speedometer: Klose
Type sketch
Sketch of the last part series No. 225–230

The A 3/5 201–230 were wet steam composite - steam locomotives of the Gotthard Railway Company (GB), which were delivered from 1894 to 1905 by the SLM . While the prototype locomotive 201 was a three-cylinder compound machine , the prototype no. 202 and the series locomotives were designed as four-cylinder compound machines of the de Glehn type . At the SBB , the express train locomotives were given the numbers 901–930.


Before the introduction of the A 3/5 from Lucerne to Erstfeld, the express trains on the Lucerne - Chiasso route were hauled by relatively small Ea 2/4 tank locomotives. On the mountain route, powerful but slow D 3/3 and D 4/4 locomotives with separate tender took over the transport of the express trains. Because of the increase in traffic, the trains were so heavy that leader locomotives were often necessary.

To shorten the journey time, the Gotthard Railway needed a powerful express train locomotive for the continuous passage from Lucerne to Chiasso. The new type of locomotive had to be able to transport an express train between Lucerne and Erstfeld with a trailer load of 250 tons and from Erstfeld on the mountain route with a trailer load of 140 tons . With the new machines, pre-tensioning work, changing locomotives in Erstfeld and water tanks on the way should be superfluous.


To meet these conditions, a tender locomotive with three coupled axles and a large boiler with high steam pressure was necessary. A two-axle front bogie was used to guide the winding tracks . A relatively small drive wheel diameter provided a sufficiently high tractive effort, but allowed a top speed of 90 km / h on sections of the valley. The Gotthard Railway was the first railway company in Switzerland to purchase machines with a 2'C wheel arrangement.


The project was presented to various locomotive factories. The Swiss Lokomotiv- und Maschinenfabrik (SLM) in Winterthur initially received the order to build two prototypes in order to find a more suitable drive for the planned use. The three-cylinder machine no. 201 worked in a network on the valley sections. The live steam removed from the boiler was first fed to the high-pressure cylinder located in the middle. Its exhaust steam then reached the two external low-pressure cylinders. The cranks of the locomotive were offset by 120 °, which resulted in an extremely favorable force diagram. On the steep ramps of the mountain route, all three cylinders worked with live steam. The machine no longer worked as economically, but had a noticeably higher pulling force.

In the case of the second test locomotive no. 202 of the de Glehn design , the steam engine, consisting of two high-pressure and two low-pressure cylinders, worked exclusively in conjunction. There was no switchover between valley and mountain line, which made the construction of the locomotive much easier. In the case of difficult approaches, live steam could also be supplied to the two externally mounted low-pressure cylinders on short sections of the route, which briefly increased the pulling force.

After extensive tests with the two prototypes, the decision was made in favor of the four-cylinder engine. Their run with four instead of three cylinders was more balanced, which meant that the crank drive was less stressed. Thanks to the network operation also on the mountain route, she worked more economically.

Description of the locomotives

Image from the A 3/5 data sheet.
An express train with A 3/5 202 in Brunnen. Photographs of this train in Brunnen were used for numerous photo montages for postcards. [3]

The inner frame was made of 30 mm thick sheet metal and was reinforced in addition to the two end beams. The long boiler was supported on these stiffeners. Because of the low-lying boiler, the firebox had to be partially located between the second and third coupling axis. The front axle was cranked as the drive axle of the internal high - pressure engine . It also carried the necessary eccentrics for the Heusinger control. The middle axis was the drive axis of the external low-pressure cylinder. It moved the Heusinger controls of the low-pressure cylinders by means of a counter crank. In the four-cylinder locomotives, the cranks of the high-pressure and low-pressure cylinders were offset by 135 °. If, as an exception, all four cylinders were working with direct steam, the eight exhaust steam strokes were evenly distributed, making the pulling force more even.

Instead of the leaf springs usually used in locomotives , a coil spring was used on the left and right of the axle bearings . It was hoped that the coil springs would give the locomotive a pleasant, smooth run. The spring supports of the first and second drive axles were connected to one another via compensating levers. The two front running axles were combined in a bogie , which was constructed the same as that of the express locomotive A 2/4 of the Jura-Simplon Railway. The pan of the pivot was suspended in two pendulums, so that the bogie could not only rotate but also perform a small lateral movement.

An uphill express train with two A 3/5 locomotives No. 201–230 leaves the Pianotondo spiral tunnel and crosses the Pianotondo viaduct.

A pressure of 14 atm could be generated in the tanks of the prototypes. The series machines were designed for a slightly higher boiler pressure of 15 atm. Four safety valves were mounted on the steam dome and above the fire box. The steam extraction for the pipe , the three injectors , the pressure gauge , the air pump for the brake and the steam heaterwere attached to a common socket in the driver's cab above the fire box. The low-pressure cylinders were located outside the frame between the rear running axle and the front drive axle, while the high-pressure cylinder or cylinders were installed between the frame above the pivot point of the front frame. Like the other locomotives on the Gotthard Railway, the machines were equipped with counter-pressure brakes.

The three-axle tender was coupled to the locomotive with a strong screw coupling and two note irons. The middle axis could move sideways to improve cornering. The horseshoe-shaped water tank was pulled through at a reduced height under the part intended for the fuel. The suspension of the axles was arranged above the axle bearings and, unlike that of the locomotive, consisted of leaf springs.

The Westinghouse air brake and the regulating brake acted not only on the tender wheels but also on the two rear driving axles. The locomotives were also equipped with Friedmann lubricators for slides and pistons, Brüggemann sand spreaders for operation with compressed air, steam heating and the Klose system speedometer .

Express train with two A 3/5 locomotives No. 201–230 below Airolo

The machines, which were very large for the time, were a technical masterpiece. The extremely good running properties of the locomotive and its great performance were excellent. Number 202 was exhibited at the National Exhibition in Geneva in 1896 , number 228 in 1906 at the World Exhibition in Milan .


The coil springs were replaced by leaf springs because their short oscillation period impaired the transmission of tensile force. The bogie brake was introduced on the Gotthard Railway from 1899. The older locomotives that had not yet been equipped with it were retrofitted so that ultimately all A 3/5 had this brake. Since the tender's water supply had proven to be scarce, the tender's water tanks were rebuilt and enlarged to 17 m³.

In 1904, on a trial basis, pumps were installed on locomotive number 222 to lubricate the axle bearings. They worked so well that two years later the other locomotives were also equipped with them. The locomotives 225-230 were finally superheater type Schmidt . After the railway accident in Bellinzona , calcium carbide- powered gas lamps were banned and replaced by petroleum lamps .

Construction year Manufacturer 2. Kessel
Schmidt type superheater
201 901 877 1894 SLM 1923
202 902 878 1894 SLM 1924
203 903 1025 1897 SLM 1924
204 904 1026 1897 SLM 1926
205 905 1027 1897 SLM 1925
206 906 1028 1897 SLM 1925
207 907 1029 1897 SLM 1926
208 908 1030 1897 SLM 1927
209 909 1031 1897 SLM 1925
210 910 1032 1897 SLM 1925
211 911 1123 1898 SLM 1925
212 912 1124 1898 SLM 1925
213 913 1125 1898 SLM 1925
214 914 1126 1898 SLM 1909 1925
215 915 1127 1898 SLM 1925
216 916 1128 1898 SLM 1925
217 917 1129 1898 SLM 1925
218 918 1130 1898 SLM 1925
219 919 1131 1898 SLM 1925
220 920 1132 1898 SLM 1925
221 921 1411 1902 SLM 1925
222 922 1412 1902 SLM 1925
223 923 1413 1902 SLM 1925
224 924 1414 1902 SLM 1925
225 925 1659 1905 SLM 1917 1926
226 926 1660 1905 SLM 1917 1926
227 927 1661 1905 SLM 1917 1926
228 928 1662 1905 SLM 1917 1926
229 929 1663 1905 SLM 1905[A 1]
230 930 1664 1905 SLM 1917 1926
  1. Overheater type Pielock

Operational use

The express train with two A 3/5 has just arrived in Göschenen. The leader locomotive will be put away shortly.

The introduction of the A 3/5 made it possible to shorten the travel time from Lucerne to Chiasso considerably. Thanks to the high performance of the machine, an additional dining car could be carried and the refreshment stop in Göschenen could be shortened. The A 3/5 were able to carry 320 tons in the flat country at a speed of 50 km / h. The trailer load for uphill travel at 40 km / h has been reduced from 140 to 120 tonnes in order to reduce the need to replenish supplies and make it easier to catch up on delays. Another locomotive of the same type was initially used for pre-tensioning, followed by the somewhat larger C 4/5for use. The adaptable express train locomotives could also be observed in front of freight trains.

In 1909 the Gotthard Railway Company was nationalized and the A 3/5 came to the SBB, where they were given the numbers 901 to 930. They were assigned to SBB District V. The Bellinzona workshop was still responsible for maintenance .

When electrical operation began on the Gotthard route in 1920, the SBB no longer had a suitable area of ​​application for the A 3/5. At 90 km / h, their top speed was lower than that of the other SBB A 3/5 express train locomotives. In the years 1923 to 1927 the locomotives were taken out of service and scrapped.


References and comments

  1. a b c d e f g h Gemäss Waldis
  2. a b c d According to Bauzeitung, Volume 24, Issue 26
  3. ^ Simplon Express or Gotthard Express. In: March 2, 2016, accessed June 23, 2019 (French).