Cardanic Rocker Arms-A Method to Reduce Valve Train Friction

Cardanic rocker arms provide a rolling action at the rocker-arm pivot. This simple design con­cept is able to reduce friction at this interface by replacing sliding friction with rolling fric­tion. Substantial reductions in valve train fric­tion result, and the measurable improvement in vehicle fuel economy is 1 to 2 percent. To ensure rolling motion over the range of action, it is necessary to include a restraining element in the design. Several restraining elements have been investigated and the final design includes a simple alignment system integrated into the pivot. Numerous tests have demonstrated that a configura­tion consisting of a stamped rocker arm and a powdered metal pivot meets passenger car engine durability requirements.