Zara Bogie
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A Krauss-Helmholtz bogie (''Krauss-Helmholtz-Lenkgestell'') is a
mechanism Mechanism may refer to: *Mechanism (economics), a set of rules for a game designed to achieve a certain outcome **Mechanism design, the study of such mechanisms *Mechanism (engineering), rigid bodies connected by joints in order to accomplish a ...
used on
steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, Fuel oil, oil or, rarely, Wood fuel, wood) to heat ...
s and some
electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a Battery (electricity), battery or a supercapacitor. Locomotives with on-board fuelled prime mover (locomotive), ...
s to improve curve running.


Operation

The
bogie A bogie ( ) (or truck in North American English) comprises two or more Wheelset (rail transport), wheelsets (two Railroad wheel, wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes ...
comprises a carrying axle connected to a coupled axle via a shaft or lever. In straight running, any radial movement of the carrying axle results in a sideways movement of the coupled axle in the opposite direction. However, the carrying axle is centred by means of two heavy duty springs just behind it. In addition the pivot pin may be allowed to move sideways, but again is held centrally by heavy springs. When travelling round a curve, the carrying axle swings to one side causing the coupled axle to move sideways in the opposite direction. In this way radial forces during curve running are more or less evened out on both axles, so that riding qualities similar to those of a normal
bogie A bogie ( ) (or truck in North American English) comprises two or more Wheelset (rail transport), wheelsets (two Railroad wheel, wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes ...
are achieved and wear and tear reduced on wheel flanges and rails. The bogie is a type of pony truck and was named after the locomotive firm of Krauss and the engineer, Richard von Helmholtz. By contrast a Bissel bogie is independently installed in the frame, and sideways guidance of the locomotive is achieved by elastic forces. The distribution of these forces is not tightly defined and, in addition, they are dependent on the curve radius.


Examples of use


Steam locomotives

Because the advantages of a pony truck come into play particularly on tight curves, the Krauss-Helmholtz bogie initially appeared on branch line, ''Lokalbahn'' and
narrow gauge A narrow-gauge railway (narrow-gauge railroad in the US) is a railway with a track gauge (distance between the rails) narrower than . Most narrow-gauge railways are between and . Since narrow-gauge railways are usually built with Minimum railw ...
locomotives. One of the first locomotives of this type was the Bavarian D VIII. On this
tank locomotive A tank locomotive is a steam locomotive which carries its water in one or more on-board water tanks, instead of a more traditional tender (rail), tender. Most tank engines also have Fuel bunker, bunkers (or fuel tanks) to hold fuel; in a #Tender ...
the bogie was located at the rear; however in the majority of cases it was at the front or - if the locomotive had to have equally good riding qualities in both directions - at both ends. Later this pony truck arrangement was also adopted by the DRG standard locomotives ('' Einheitslokomotive'') of the
Deutsche Reichsbahn The ''Deutsche Reichsbahn'' (), also known as the German National Railway, the German State Railway, German Reich Railway, and the German Imperial Railway, was the Weimar Republic, German national Rail transport, railway system created after th ...
, e.g. on the ten-coupled classes: 44, 45, 50 and 85. An exception was the Class 84, that was fitted with Schwartzkopff-Eckhardt II bogies or Luttermöller axle drives. The tender locomotives of classes 41 and 45 only had a Krauss-Helmholtz bogie at the front; the trailing axle was housed in a Bissel bogie. The tank locomotives of Class 85, like some of the Class 64 and 86 engines, had two Krauss-Helmholtz bogies.


Electric locomotives

Even the
electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a Battery (electricity), battery or a supercapacitor. Locomotives with on-board fuelled prime mover (locomotive), ...
s of Reichsbahn classes E 04, E 17, E 18 and E 19 were fitted with comparable pony trucks, known as AEG frames (''AEG-Gestell''). Because the axles had external bearings, the lever linkage also had to be on the outside, a characteristic detail of these locomotives.


Italian bogie

In
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
, the Krauss-Helmholtz bogie was improved around 1900 by Giuseppe Zara, a technician of the Rete Adriatica and later of the Ferrovie dello Stato; by modifying the structure, rearranging the weight distribution and allowing the bogie to also move transversally respective to the locomotive's frames, he obtained the Italian bogie (a lighter and somewhat different version was the later Zara bogie). It saw widespread use, being fitted on many Italian steam locomotive classes, like the FS Class 625, FS Class 740 and FS Class 685. The electrical locomotive
FS Class E.432 FS Class E.432 was a class of Three-phase AC railway electrification, three-phase electric locomotives of the Italian State Railways. Forty of these 1′D1′ locomotives were built in 1928 by Società Ernesto Breda and two have been preserved. H ...
also used this bogie type.


See also

*
Bogie A bogie ( ) (or truck in North American English) comprises two or more Wheelset (rail transport), wheelsets (two Railroad wheel, wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes ...
* Cleminson's patent * Heywood radiating axle locomotives * Lateral motion device * List of DRG locomotives and railbuses *
List of Bavarian locomotives and railbuses This List covers the locomotives and railbuses of the Bavarian railways, excluding those of the Palatinate (region), Palatinate (''Pfalz''). The locomotives and railbuses of the Palatinate when it belonged to Kingdom of Bavaria, Bavaria are in th ...
*
List of Prussian locomotives and railcars This list gives an overview of the locomotives and railcars that were in the Prussian state railways. Also included are the locomotives of the Grand Duchy of Hesse State Railways (''Grossherzoglich Hessischen Staatseisenbahnen'') and the Pruss ...
*
Minimum railway curve radius The minimum railway curve radius is the shortest allowable design radius for the centerline of railway tracks under a particular set of conditions. It has an important bearing on construction costs and operating costs and, in combination with ...


References


External links


Photograph of the bogie on a South African NG 15 (610 mm gauge)
{{Locomotive running gear Steam locomotive technologies Bogie