Rollbocks,[1] sometimes calledtransporter trailers, are narrow gauge railway trucks orbogies that allow a standard gauge wagon to 'piggyback' on a narrow-gauge line. The Vevey system enables a coupled train of standard gauge wagons to be automatically loaded or rolled onto Rollbocks, so that the train can then continue through achange of gauge.
The system uses a pair ofnarrow gauge (750 or 1,000 mm) rails laid in a pit that is built in the middle of astandard gauge track, which is elevated by about 30 cm. It allows theRollbock bogies to sit underneath the standard gauge tracks and as theRollbock train is pulled out of theRollbock siding each bogie picks up one axle of a standard gauge wagon as it rises out of theRollbock pit. Thus twoRollböcke are needed for a twin-axle wagon. They were a development of thetransporter wagon (Rollwagen), designed to keep cost and weight down by avoiding the need for a complete wagon.
The original invention goes back to theRollwagen of theSchweizer Maschinenfabrik Winterthur (Swiss Locomotive and Machine Works,Winterthur) or SLM patented in 1880. It is a simple system for light loads that found applications even when the superiorLangbein system was invented in 1881 by theMaschinenfabrik Esslingen (Esslingen Engineering Works) named after Paul Langbein being the director of the facilities inSaronno, Italy.[2]
A similar design appeared on thePaw Paw Railroad in Michigan in the late 1870's as an improvement from theRamsey car-transfer apparatus, and it's inventor C.F. Allen also obtained a patent on his transfer truck in 1880, although the truck would ultimately see limited use in the United States compared to its European counterparts.[3]
TheLangbein system uses pairs of claws which are folded up laterally by hand, to form a yoke around the axles of the standard gauge bogies. When the bogies are pulled out of the pit the standard gauge wheels can sink onto theRollbock to find support. This method enables theRollbock wagons to traverse curves as sharp as 15 m (49.2 ft) radius and, when fully loaded, they could be moved over narrow gauge tracks at a safe speed of 13 mph or 21 km/h.[4]
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In 1974 a refinement of the concept was developed for theYverdon–Ste-Croix railway in Switzerland. Unlike the Langbein system, the Vevey system requires no manual intervention to fix the standard gauge axles over the narrow gauge bogies. In this system, rather than the axle being supported, the wheel flanges of the wagons are cradled in brackets projecting from the side of theRollbock. This lowers the centre of gravity and increases stability. Many modernRollbock users have converted to the Vevey System. They are used with a speed of up to 40 km/h, either loaded or empty. TheVevey Technologies company was bought by Bombardier in 1998.[5]
They are used extensively inSwitzerland and inSpain,[6] in the latter country to transportstandard gauge vehicles onbroad gauge lines.
They are also in use on theHarz Narrow Gauge Railways to transport limestone from the Unterberg quarry toNordhausen, where they are transferred to the DB system at a pit between the station and Hesseröderstraße. Trains are diesel-hauled and typically consist of 12 22 m3 (780 cu ft) Fccpps ballast hopper wagons fromVoestalpine Railpro; theRollböcke are painted bright pink.
Until the 1990s theRollbock sidings atWernigerode were used every day to transport goods to and from the various metallurgical factories attached to theHarz Narrow Gauge Railways in the immediate area. Similarly it was used extensively on the Saxon narrow gauge system west ofDresden to transportchina clay toMeissen.
Using rollbock technology requires that the narrower gauge network must be built to astructure gauge large enough to accommodate theloading gauge of standard gauge wagons, and that negates one of the cost advantages of narrower gauge construction. The system was tested for thenarrow gauge railways in Saxony around 1900 but it found only rare application – tracks requiring higher transport capacity wererebuilt to1,435 mm (4 ft 8+1⁄2 in)standard gauge instead. However it is also possible to use the wagons of the narrow gauge loading gauge type built with standard gauge axles which allows them to run at full speed on standard gauge tracks, piggybacking them on the short section in the mountains byRollbock bogies. This application requires that the receiver of the freight is able to unload those wagons, so they have found only limited use.
