Rocker Arms and Rocker Shafts

The rocker shafts are hollow to allow an oil supply to the hydraulic lifters that are retained in the end of the rocker arm. The valves are opened by roller rocker/hydraulic lifter assemblies, which pivot on the rocker arm shafts.

Fig 1: Intake And Exhaust Valve Rocker Mechanism

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Intake Rocker Arm

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 3: Exhaust Rocker Arm

Courtesy of BMW OF NORTH AMERICA, INC.