The connecting rod connects the piston to the crankshaft. It is fastened to the piston at its little end, by a piston pin, also known as a gudgeon pin.
In some engines the pin is a press fit in the small end of the connecting rod.
In others, it is clamped to the connecting rod with a clamping bolt.
Another method lets the pin float in both the piston and connecting rod, and it is held with circlips. There is a bearing in the small end of the connecting rod.
The big end of the connecting rod has a detachable cap, and carries 2 halves of the big end bearing. The big end is attached to the crankshaft at the crankpin journal.
Connecting rods must be very strong and rigid, and as light as possible. They are subject to stretching, compressing and bending, so they are highly stressed.
They are cast or forged to form an H near the small end and an I near the big end.
This shape provides greater strength to resist the stresses than a solid rod of the same mass.
To maintain engine balance, all the connecting rods in an engine are a matched set.
Source: CDX Global
