Browse Publications Technical Papers 2000-01-2949

Preventing Catastrophic Camshaft Lobe Failures in Low Emission Diesel Engines 2000-01-2949

With the drive to reduce emissions and improve fuel economy, fuel injection pressures have increased. This has increased Hertzian stresses on the roller follower cam system to the point that cam lobe contact fatigue failure has become the “Achilles heel” of diesel engine durability in the 1990s. Contact fatigue failures have occurred on both injector lobes and the exhaust and inlet lobes. This is particularly the case in fleets with frequent engine shut downs and starts, stop-go service and in some line-haul fleets.
This paper describes field service cam failures across several engine types and applications. In our experience supporting fleet customers in cam failure analysis, we found that a combination of ten critical independent variables must be correct in order to prevent cam lobe contact fatigue failures. These variables are each discussed separately.
In bench tests simulating stop-go applications, we found that the silicon nitride roller on a steel pin had low and constant friction under flooded and starved lubrication conditions. In contrast, the bronze pin and steel roller had severe stick-slip with very high friction, which could cause roller skidding on the cam. The silicon nitride roller and steel pin have provided long cam life in many applications.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Camshaft/Follower-Design for Different Stress Behavior in Heavy Duty Diesel Engines


View Details


A New Sensor Element with High Suppression of External Fields for Rotational Speed Sensors in Engine Management Applications


View Details


Development of Continuously Variable Valve Lift Mechanism for Improved Fuel Economy


View Details