X engine

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X motors are reciprocating piston motors with four rows of cylinders arranged in an X shape. They were used as aircraft engines, for example the Italian Isotta Fraschini Zeta and the US Packard 1A-2775 . These were 24-cylinder engines, as well as the American Allison X-4520 , the German Daimler-Benz DB-604 and the British Rolls-Royce Vulture . However, the last three examples can be classified more precisely as in-line star engines with 24 cylinders, since the cylinder bank angles are each 90 ° (symmetrical).

A modern X-engine is the Chelyabinsk diesel engine A-85-3A (12N360) , which has an output of around 1,103 kW (1,500 hp) and is used to drive the new Russian T-14 main battle tank .

to form

There are several forms of X-motors:

  • One is symmetrical - i.e. H. all four cylinder banks are at 90 ° angles around the crankshaft (90 ° / 90 ° / 90 ° / 90 °). This form is due to its symmetry - analogous to the symmetrical V-type engine (180 °) and the symmetrical Y-motor (120 ° / 120 °) - better than a star or series of radial engine to look at.
  • Another design, on the other hand, has the two opposite cylinder banks arranged at angles different from 90 ° (e.g. 120 ° / 60 ° / 120 ° / 60 °).
  • In the third variant, three cylinder banks are arranged at the same angle - e.g. B. 45 ° / 45 °, the third and fourth cylinder bank angle in this case being calculated as 135 °.


The advantage of the X-engine design compared to in-line, boxer, V, W or Y-engines is that a relatively large number of cylinders and thus a lot of displacement and power can be accommodated per engine length.

Web links

Commons : X-Motors  - Collection of images, videos and audio files

Individual evidence

  1. Diesel drive 12N360. (No longer available online.) April 28, 2015, archived from the original on August 23, 2015 ; Retrieved April 28, 2015 (Russian).
  2. А-85-3А. army-guide.com, accessed October 13, 2018 (Russian).