The Piston Assembly

Piston rings provide a seal between the outside of the piston and the inside wall of the cylinder. The piston of our Four Stroke Cycle Engine has two compression rings and one oil rings.

Parts of the Piston Assembly

Piston, connecting rod, crankshaft and flywheel of a Briggs and Stratton one cylinder engine

Piston Rings


1. To prevent leakage of the air-fuel mixture in the combustion chamber.
2. To assist in controlling the amount of oil on the cylinder wall.



1. To prevent excessive amounts of oil from working up into the combustion chamber.

Check out the piston page to learn about the where these rings go on the piston.


The Piston

This picture gives you a description of what a piston looks like and the different parts of the piston. A piston is a cylindrical and moves up and down inside the cylinder. Use the information included below to help when you complete your worksheet for this unit.
1. Piston Head - Top of the piston

2. Ring Lands - The ridge between ring grooves

3. Ring Grooves - The grooves where the compression and oil rings go

4. Oil Holes - These allow oil to move from the piston to the wall of the cylinder

5. Piston Pin - Holds the connecting rod in the piston

6. Lock Ring - Hold the piston pin in place

7. Skirt - The bottom part of the piston



[Introduction] [Engine Displacement] [Engine Valve] [Engine Lubrication] [Four Stroke Cycle]