Bearing is a device supporting a mechanical element and providing its movement relatively to another element with minimum power loss.
The rotating components of internal combustion engines are equipped with sleeve type sliding bearings.
The reciprocating engines are characterized by cycling loading of their parts including bearings. Such character of the loads is a result of alternating pressure of combustion gases in the cylinders.
Rolling bearings, in which a load is transmitted by rolls (balls) to a relatively small area of the ring surface, can not withstand under the loading conditions of internal combustion engines.
Only sliding bearings providing a distribution of the applied load over a relatively wide area may work in internal combustion engines.
The sliding bearings used in internal combustion engines:
The top dead center (TDC) of a piston is the position where it is nearest to the valves; bottom dead center (BDC) is the opposite position where it is furthest from them. A stroke is the movement of a piston from TDC to BDC or vice versa together with the associated process. While an engine is in operation the crankshaft rotates continuously at a nearly constant speed . In a 4-stroke ICE each piston experiences 2 strokes per crankshaft revolution in the following order. Starting the description at TDC, these are: