A connecting rod is a rigid member which connects a piston to a crank or crankshaft in a reciprocating engine. Together with the crank, it forms a simple mechanism that converts reciprocating motion into rotating motion.
A connecting rod may also convert rotating motion into reciprocating motion, its original use. Earlier mechanisms, such as the chain, could only impart pulling motion. Being rigid, a connecting rod may transmit either push or pull, allowing the rod to rotate the crank through both halves of a revolution. In a few two-stroke engines the connecting rod is only required to push.
Today, the connecting rod is best known through its use in internal combustion piston engines, such as automobile engines. These are of a distinctly different design from earlier forms of connecting rod used in steam engines and steam locomotives.
There are a few options of material for making the connecting rod, – steel, like most OEMs, aluminum, and titanium.Titanium connecting rods have been used for decades in high-end applications where the strength and longevity of steel is required, but the lightweight characteristics of aluminum are desired. Besides, titanium has a lower thermal expansion rate than steel and much less than aluminum, which allows the racer to hold closer tolerances within the engine.