Piston rings:

· Works as a seal between piston and cylinder.
· Generally there are 3 grooves in the piston, provide seats for piston rings.
· The upper 2 two rings are compression rings, and the third one is oil ring.
· The role of oil ring is to scrape the extra oil from the cylinder wall so that proper volume of oil remain in the combustion chamber.
· The piston rings are usually made by wear resistant high carbon steel.
· The top side of the piston rings is marked as “Top”, zero.





Cylinder:

· The is made up of aluminum alloy casting and is lined with a special cast iron sleeve called liner.
· It is very necessary to make the inner surface of cylinder super smooth and wear resistant cause there is continuous reciprocating motion of piston takes place.
· The outer surface of cylinder has fins these helps to enlarge the surface area of outer cylinder which increases the heat deception rate.


Connecting rod:

· The connecting rod connects piston to crankshaft this converts the reciprocating motion of piston into rotary motion of crankshaft.

. The connecting rod is made by drop forging or casting.

· The connecting rod is made of alloy steel to reduce it’s weight.

· Generally it has an “I” shaped cross section.

· The big end of connecting rod is secured to crank pins with specific steel bolts and nuts.

· The small end of connecting rod is connected with the piston with the help of gudgeon pin.





Crankshaft:

Single Cylinder ENGINE, Assembly type crankshaft.
Multi Cylinder ENGINE, Integrated type crankshaft.


· Generally medium carbon steel (C 0.25%-0.45%) is used to made crankshaft.

· The crankshaft is supported with connecting rod held there by crank pin and main bearings fitted in the crankcase casting.

· The one side of crankshaft is connected with flywheel, used to run the engine on mean torque.

· The crankcase holes into which the crankshaft journals are inserted are provided with the oil holes, through which oil is fed to lubricate the main bearings and connecting rod big end etc.

Twin-cylinder crankshaft:


 · When the crank pins are situated at the same side the crankshaft is called a 360° crankshaft.

· When situated on opposite sides then called 180° crankshaft.