| SBB-CFF-FFS Ae 4/8 | |
|---|---|
| Power type | Electric |
| Builder | SLM Winterthur, BBC Baden |
| Build date | 1922 |
| Total produced | 1 |
| UIC classification | 1′Bo1′+1′Bo1′ |
| Gauge | 1,435 mm (4 ft 8 1⁄2 in) |
| Wheel diameter | 1,610 mm (5 ft 3 in) |
| Trailing wheel diameter |
950 mm (3 ft 1 in) |
| Length | 21,000 mm (68 ft 11 in) over buffers |
| Weight on drivers | 73 tonnes (72 long tons; 80 short tons) |
| Locomotive weight | 127 tonnes (125 long tons; 140 short tons) |
| Electric system | 15 kV 16⅔ Hz AC |
| Current collection method |
Pantograph |
| Traction motors | Four |
| Transmission | Buchli drive, Tschanz drive |
| Multiple working | Not available |
| Top speed | 90 km/h (56 mph) |
| Power output | Continuous: 1,620 kW (2,170 hp) at 65 km/h (40 mph) One hour: 1,885 kW (2,528 hp) at 62 km/h (39 mph) |
| Locomotive brakes | Air |
| Train brakes | Air |
| Safety systems | Signum |
| Career | SBB |
| Number | 11100 (11300 from 1929) |
| Nicknames | Bastard, Tatzelwurm, Grandmother |
| Withdrawn | 31 December 1964 |
The Ae 4/8 was a prototype locomotive of the Schweizerischen Bundesbahnen (Swiss Federal Railways) (SBB) for the testing of the electrical operation. The locomotive was equipped with two different drives - therefore the nickname Bastard. Because of its three-part locomotive body it obtained the nickname Tatzelwurm too.
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During First World War the SBB decided to establish the electrical operation on the main lines as fast as possible. Therewith one wanted to become independent of the coal supplies of the warring neighboring countries. Since the technology of the electrical railway service was still new, suitable locomotive constructions had to be found.
Therefore the SBB procured several prototype locomotives. Beside the Be 3/5 12201, Be 4/6 12301, Be 4/6 12302 und Ce 6/8I 14201 with coupling rods the SBB procured the Be 2/5 prototype locomotive with fully spring-loaded drives. For the execution of testing in the operation environment this locomotive was too faint and too slow. Therefore the SBB ordered already 1919 a second prototype locomotive at SLM and BBC. As the Be 4/6 this prototype locomotive should have four drive axles. The requirement specifications corresponded to those of the Be 4/6. However, for the operation in the express train service, a maximum speed of 90 km/h was required.
The Be 4/6 utilized the maximum axle load of 20 t completely. The motors for the Ae 4/8 were heavier than those of the Be 4/6. Therefore the Ae 4/8 was planned with two more idle axles from the beginning. In contrary to the Be 4/6 Bogie locomotive the Ae 4/8 was built as a frame locomotive with a twice articulated body. This articulated layout allowed good operation in courves, even with the heavy, frame mounted motors. Because of this layout the locomotive was nicknamed Tatzelwurm too.
The locomotive consisted of three bodies connected with gaiters. The two outer bodies had short cabinets. The chassis consisted of two short-coupled frames. Each of them contained two drive axles, one leading Bissel axle and one trailing Adams axle.The frames were – as at the Be 4/7 – coupled directly with a connecting rod and two auxiliary couplers. Else than the outer bodies, which were fixed with the frames, the center body laid on a bridging slab, which did not transfer any tension or pressure forces. The bridging slab shored up on the outer frames over a pivot and horizontal springs between the inner drive axles and the Adams axles.
The transformer was mounted in the center part of the locomotive. For dismounting the transformer the roof of the center locomotive body was removable. The roofs of the outer parts of the locomotive body were removable separately left or right side. The side elements of the tree parts of the locomotive body were removable segmentually. The center body including the bridging slab was liftable as a whole. The cabinet at cab I contained two compressors. The brake-transformer was located in the cabinet at cab II. A lifting jack and a toolbox were stored in this cabinet too.
The locomotive was equipped was four identical motors which were mounted fixed in the frames. But the fully spring-loaded drives were different at each frame. Therefore the locomotive was also nicknamed as Bastard. On side I Tschanz drives were mounted. The basic feature of this drive was the gimbal principle for the transmission of the torque between the big gearwheel, which was part of the gearbox connected to the unsprungly mounted motor and the suspended drive axle. Due to the fact, that the gimbal-drives succeeded to be very short, it was possible, to omit – different than at the Be 2/5 – the hollow shaft to the other side of the locomotive. The diameter of the big gearwheel was limited by the loading gauge. Therefore the cog transmission had to be cascaded in two steps because the engine speed of all four motors was identical. The locomotive side II contained – as the single side mounted Tschanz drives in side I – single side mounted Buchli drives. Due to the very heavy weight of those drives they were mounted transversal. The use of both side installation of the drive – as used in the Be 2/5 – was not considered as necessary anymore.
The brake equipment of the locomotive was as follows:
The total weight of the locomotive of 127 t – incidentally the same as the one of the later built Ae 4/7 – lead to a total weight of 18.6 t at the drive-wheels. The limit of 20 t was therefore fulfilled. Incidentally the axle load was quite disharmonious. The locomotive part I standed out by obvious higher axle loads. The axle loads, started at the Bissel axle of the locomotive-part I are shown consecutively:
14.0 t – 18.3 t – 18.6 t – 14.5 t – 14.2 t – 18.1 t – 17.9 t – 11.2 t
Therefore the sand distributor was of very high importance. Each drive wheel could be assisted with sand in both directions of motion by using compressed air.
The electrical part was adopted from the Be 4/6 12303.
The following components were different:
Transformer, oil propulsed main switch and stepping switch were located in the center body. The power supply from the catenary occurred over the two diamond-shaped pantographs mounted on the two end bodies. At the beginning of service both pantographs had to be lifted since they were equipped only with a single sliding bar without rocker. The cabinets for the reversing pole shunts and the brake resistors were mounted in front of the pantographs towards the end of the outer bodies of the locomotive.
The 18-steps flat track BBC stepping switch was mounted to the transformer. It was driven by a battery supplied direct-current motor. At the beginning the stepping switch was controlled by a crank handle, later by a control-wheel. It was possible to move the stepping switch by hand, but only inside of the center locomotive body at the stepping switch.
The cooling of the transformer oil was carried over cooling tubes located on both sides under the center locomotive body. An oil pump was used for the circulation of the oil. Each tube system was mounted in a shaft. A fan pressed air from the interior of the body through this system.
The motors in the end bodies were connected in series circuit. The electrical separation of one locomotive side was possible by blocking the respective reversing switch.
The electrical brake was an alternative current excited resistor brake. Together with the reversing pole shunts they were mounted on the roof over the cabs, where they were cooled by the head wind.
The locomotive was equipped with the following auxiliary systems:
At the beginning of the electrical traction the look of electrical locomotives was unfamiliar for the railroaders. The air grilles reminded them about wrinkles. Therefore the locomotive was sometimes also nicknamed as “grandmother”.
After delivery in March 1922 the locomotive was used first on the Bern (Berne) – Thun line, because this line was the first one electrified with 15 kV 16 ⅔ H. But the locomotive was – as the prototype locomotives with rod drives – never busy on the adjacent Lötschbergbahn (Bern-Lötschberg-Simplon railway) from Thun to Brig. The home of the locomotive in Berne did not last long time. The services around Berne were followed by a test phase without fixed service plans including the Gotthardbahn (Gotthard railway).
1925 the locomotive was assigned to the Basel (Basle) depot. This assignment was not changed anymore until the retraction of the locomotive.
The roster of 1927 included – together with two Ae 4/7 – the lead of two fast train pairs Basle – Zürich and back with a daily performance of 416 km. Shortly after the Ae 4/8 disappeared from the rosters. With its performance definition, which was about 90% of the Ae 4/7, the locomotive was universally operatable. The maximum speed of 90 km/h allowed to lead fast trains. Therefore the locomotive was used very often in cases of a capacity needed duplication of a fast train. In this function the locomotive lead fast trains to Zurich, Chur, Luzern, Berne and Spiez.
Usually the Ae 4/8 was leading freight trains to Zurich and Winterthur. During the last years of service the locomotive was used for services Basle – Zurich – Winterthur, then commuter trains around Olten and freight trains around Solothurn. 1961 the locomotive was even new cogwheels were mounted in the Tschanz-drives.
Oktober 7th 1964 a locomotive driver reported sparks at the flat track switch. As a consequence of this the locomotive was towed to the Zurich Repairing Shops. But the shop was too busy because the duties it had to provide for the additional services for the National Exhibition 1964 (EXPO 1964). Therefore the locomotive was parked for the time being. The General Management of the SBB had promised to discharge all the veterans after the EXPO 1964. For this reason the Ae 4/8 immediately scrapped.
The technical importance of the locomotive was marginal. At the moment of the handover of the Ae 4/8 six Be 4/7 with the Westinghouse-drive and the first few Ae 3/6I with the BBC-drive were already in service. Due to its complexity the Tschanz-drive was not pursued anymore. Astonishingly the last parts of this drive were scrapped only 1967 in the main shop in Zurich.
Originally the locomotive carried – as a lot of the electrolomotives of the SBB – a brown paint. Later it was replaced by a green one. At the procurement 1922 the locomotive was named and numbered as Ae 4/8 11000. 1929 the service number was changed to 11300. The same number was assigned later to a Re 4/4II.
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