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The Prussian Class P 8 of the Prussian state railways (DRG Class 38.10-40 of the Deutsche Reichsbahn) was a 4-6-0 steam locomotive built from 1906 to 1923 by the Berliner Maschinenbau (previously Schwartzkopff) and twelve other German factories to a design by Robert Garbe. It was intended as a successor to the Prussian P 6, which was regarded as unsatisfactory. == Construction == Because Garbe was an advocate of the simplest possible designs, a straightforward, superheated steam, two-cylinder driving gear was envisaged. The P 8 benefited especially from superheated steam technology, which had just been developed by Wilhelm Schmidt (nicknamed 'hot steam Schmidt'), that led to outstanding performance for those times. The P 8 was a very economical locomotive that did not make great demands on the ability of the engine driver. At the outset Garbe even designed the P 8 as an express train locomotive, with the expectation of attaining a top speed of . As a result, the first units were fitted with low-wind-resistance, tapered driver's cabs. The enthusiasm of crews for the new locomotive was at first muted. The boiler was very effective at evaporation (there was already evidence of a combustion chamber at the front end of the firebox), however against that there were numerous teething troubles, e.g. the driving rod bearings were too small, which continually led to overheating, and the loosely coupled Prussian box tender, which led to disturbing riding qualities when running tender-first. Its riding performance was never fully satisfactory. As a result of poor weight compensation the top speed estimated by Garbe was never achieved and it was eventually assessed at 100 km/h (60 mph). One characteristic feature of the P 8 is the large distance between the centre and rear coupled axles. At the outset the P 8 only had a steam dome behind the sandbox; later a forward feed dome was added. Further constructional changes affected, ''inter alia'', the driver's cab roofs, the smoke deflectors and various external assemblies. There would appear to have been a number of boiler variations. The following combinations can be seen in photographs: 1/. boiler feeds on sides on boiler, steam dome in front of sandbox 2/. boiler feeds on sides of boiler, steam dome behind sandbox 3/. boiler feeds on top of boiler without feed dome, steam dome behind sandbox 4/. boiler feeds on top of boiler with feed dome, steam dome behind sandbox At least some of very early engines (those with the "V" cabs) carried type (1) boilers and this type appears to have been the standard in the early years. Types (3) and (4) do not seem to have appeared until after WWI but ultimately became prevalent. See "100 Jahre Preussische P8" (''Eisenbahn Kurier''). In order to be able to turn the locomotive even on small turntables, the Prussian state railways fitted the P 8 with tenders that originally held 21.5 m³ of water and 7 t of coal. Later the Deutsche Bundesbahn coupled the Class 38 with the tenders of withdrawn wartime locomotives the so-called 'Kriegslokomotiven', especially the bathtub tenders (''Wannentender''), which could carry more fuel. In addition the top speed when running tender-first was increased from to . On the other hand, the Deutsche Reichsbahn also used tenders of DRG Class 17 steam locomotives that had been taken out of service. These were the so-called long-distance tenders. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prussian P 8」の詳細全文を読む スポンサード リンク
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