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Crankcase with cast-in cylinders of a six-cylinder in - line engine from BMW

The crankcase is an important part of combustion engines as the crankshaft bearing . Depending on the manufacturer, the definition of the crankcase differs and is also equated with the engine block . According to the mechanical engineer Franz Pischinger , the crankcase is the combination of cylinder , cooling jacket and engine housing.


In four-stroke engines, the crankcase is usually closed at the bottom with the oil pan . This also serves to collect the lubricant and to store oil. The majority of all small and medium-sized crankcases produced consist of a cast part, with cast iron , nodular cast iron (for higher loads) and light metal (predominantly aluminum) being used as the material. Welded constructions made of steel or cast iron are also used for larger motors.


The tasks of the crankcase include:

In two-stroke engines , the crankcase is also used to charge exchange used as irrigation pump and for pre of the fresh gas. The transfer channels connect the crankcase with the cylinder . Because of the volume changes caused by the piston stroke, overpressure occurs periodically in the crankcase, through which the fresh gas flows through the overflow channels into the cylinder, where it displaces the burned exhaust gas. In two-stroke engines without circulating lubrication , the sucked-in fuel-oil-air mixture , which is passed through the crankcase, supplies crankshaft and connecting rod bearings as well as pistons, i.e. all moving parts, with lubricant.

See also


  • Jan Drummans: The car and its technology. 1st edition, Motorbuchverlag, Stuttgart 1992, ISBN 3-613-01288-X
  • Wolfgang Eifler et al .: Küttner piston machines . 7th edition, Vieweg + Teubner - GWV Fachverlage GmbH, Wiesbaden 2009, ISBN 978-3-8351-0062-6


  1. ^ Franz Pischinger: Internal combustion engines , lecture reprint, Volume 1, self-published, Aachen: September 1986, p. 309.
  2. Wolfgang Eifler, u. a .: Küttner piston machines . 7th edition, Vieweg + Teubner - GWV Fachverlage GmbH, Wiesbaden, 2009, p. 239.