Timing Chain: Description and Operation

Single-row primary and secondary chains drive the camshafts of each cylinder bank. The primary chains transmit the drive from two sprockets on the crankshaft to variable valve timing units on the intake camshafts.

Each chain has an hydraulic tensioner operated by engine oil. A jet of oil from the end of each tensioner lubricates the chains. While the primary chain tensioners act on pivoting flexible tensioner blades, the secondary chain tensioners act directly on the chains.

Guide rails are installed on the drive-side of the primary chains. The secondary chains transmit the drive from the variable valve timing units to sprockets on the exhaust camshafts.

A key locates the two drive sprockets on the crankshaft and these are retained in position by the crankshaft torsional vibration damper.