Crankcase

The crankcase is formed as a bearing the crankshaft of internal combustion engines, an important part. Depending on the manufacturer, the definition of the crank case is different and there is also equated with the engine block. After mechanical engineer Franz Pischinger the crankcase is the composite of cylinders, cooling jacket and engine casing.

Construction

For four-stroke engines, the crankcase is usually closed at the bottom with the oil sump. This also serves to collect the lubricant and oil storage. The majority of crankcase made ​​of small and medium size consists of a cast member, cast iron ductile iron ( for heavy duty ) and light metal ( mainly aluminum) find use as material. For larger motors are also welded constructions of steel or cast iron use.

Function

The duties of the crankcase include:

• The cooling of the engine
• The absorption of forces (gas - and inertial forces resulting from the combustion process and of the oscillating piston movement )
• Optionally recording the cylinder liners

For two-stroke engines, the crankcase is also used to as a mud pump, and the charge cycle for pre-compaction of the fresh gas. The transfer ports connect the crankcase with the cylinder. Due to changes in volume caused by the piston stroke is formed periodically a positive pressure in the crankcase, by means of this flowing through the fresh gas into the cylinder transfer ducts, where it displaces the combusted exhaust gas. For two-stroke engines without circulation lubrication system supplies the fuel sucked oil -air mixture which is passed through the crankcase, crankshaft and connecting rod bearings and pistons, which are all moving parts with lubricant.