Crankshaft Pulley/Mass Damper

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

At the front of the crankshaft is a crankshaft pulley/mass damper which drives the primary drive belt for the ancillary components. A tuned torsional mass damper is incorporated into the crankshaft pulley which dampens vibration in the crankshaft produced by the combustion process. Each time a cylinder fires, torque is applied to the crankshaft via the pistons and connecting rods. The crankshaft deflects in reaction to the torque which creates a vibration when the torque is dissipated. The mass damper absorbs the vibration, reducing fatigue damage to the crankshaft.

A torsional isolator is incorporated into the crankshaft pulley to provide isolation and reduce primary drive belt loads to the ancillary components. The crankshaft pulley is located over an alignment roll pin that is press fitted into the crankshaft nose. Four bolts secure the crankshaft pulley to the crankshaft. An O-ring seal provides a seal between crankshaft pulley hub bore and the crankshaft nose outer diameter to prevent oil leakage during engine running conditions.

The crankshaft pulley has a timing mark that, when aligned to a corresponding timing feature on the front cover assembly, aligns the crankshaft to 50° After Top Dead Center (ATDC) on Cylinder 1. The crankshaft pulley/mass damper assembly is not a serviceable component and must not be disassembled.