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Paxman History Pages - Paxman Diesel Engines Since 1934

ZH
ZH engine and generatorIntroduced in 1954, this was a horizontal or 'flat' 6 in-line cylinder engine. Evolved from the YH, it was essentially half (i.e. one bank) of a Vee 12 YH. The ZH was designed for British Railways primarily as an under-floor mounted power unit for railcars. Paxman was unsuccessful in persuading BR to adopt the engine for this application but large numbers of the pressure-charged version were supplied for the Class 17 'Clayton' Type 1 diesel-electric locomotive used mainly in the Scottish Region.

Lycoming O-1230 Flat-12 Aircraft Engine
https://oldmachinepress.com/2018/04/20/lycoming-o-1230-flat-12-aircraft-engine/

While the O-1230’s power output was on par with many of its contemporaries, such as the Allison V-1710, the O-1230 did not offer the same development potential or reliability as other engines.

https://oldmachinepress.com/2018/05/20/lycoming-xr-7755-35-cylinder-aircraft-engine/

The Lycoming XR-7755 was the most powerful aircraft engine in the world when it was built. The XR-7755 was the culmination of Lycoming’s experience with radial and liquid-cooled engines. Conceived in 1943, such a large engine was not needed by the time it first ran in 1946.