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A significant percentage of energy is lost in internal combustion engines due to valve train friction. The reduction of friction losses of a valve train is an important factor to improve significantly fuel efficiency and consequently emissions reduction. The friction loss of valve train includes the losses of the individual components and factors, such as spring load, temperature, lubricant type, mass of components, operating conditions and others. The breakdown of the friction within the valve train is necessary for the implementation of effective optimization measures. This paper presents an analysis of some influence factors associated to friction loss, utilizing the Design of Experiments approach. The results are based on dynamic measurements on a single overhead camshaft (OHC) engine valve train, performed on a test rig developed for friction torque measurements.

More efficient and more reliable methods to analyze the performance of the bearing test samples help to reduce validation time during development of rolling bearings. This paper presents a study of the impact on airborne noise and structural borne noise of especial prepared rolling bearings with angular contact submitted for durability tests. The study aims to link specific bearing failures to characteristics in airborne noise and structural borne noise using for instance the “envelope technique”. In the future these patterns will enable more effective online monitoring of failure evolution.

The main purpose of the lubrication in the rolling bearing is to avoid and to reduce the metal to metal contact, thus it is possible to reduce the friction and to prevent the wear between the balls and the raceways. Consequently, the rolling bearing should work with grease or oil inside to guarantee an oil film between the balls and the raceways, thus this grease should stay inside the bearing. To avoid the grease loss the bearing normally may have a sealing but even so a little grease loss can occur. Hence the present investigation was initiated because of the need to understand a grease loss and the basic parameter that has influence on this. To help the elaboration of the experimental tests was used a DOE technique, thus it was possible to determinate simultaneously the individual and interactive effects of many factors that affect in the grease loss.