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DYNAMICALLY loaded bearings on which the load alternates or rotates in direction and on which the load intensity is constant or varies are discussed here. Practical bearing engineering, the authors say, has neglected this type although it represents the most important bearings in aircraft and automotive engines. The relative load-carrying capacity of a finite-length bearing is shown by the authors to be proportional to the expression: (2 load rpm - journal rpm). The test setup used to prove the formula is described by the authors. Oscillograph records are presented which show the change in oil film thickness as the load conditions are varied. The effect of running out of oil, on oil film thickness is demonstrated by the authors to be identical to approaching the critical value of zero load-carrying capacity as defined by the expression in the previous paragraph. A method for investigating the capacity of engine bearings is also discussed by them.

COMBUSTION roughness associated with lateral flywheel vibration can be controlled more effectively by adding a suitable damping system to the flywheel than by altering combustion-chamber shape. The authors reach this conclusion because their quantitative study shows that the degree of shock excitation is dependent on different pressure characteristics at different engine speeds. At 1000 rpm, low rates and accelerations of pressure rise, obtainable by proper combustion-chamber design, will reduce combustion roughness. However, at 3500 rpm, it is maximum pressure - which is not dependent on combustion-chamber design - that governs vibration intensity. If vibration is to be diminished by a reduction in maximum pressure, either the spark must be retarded or the volumetric efficiency decreased. Maximum kinetic energy proved to be the most suitable criterion of disturbance over the entire range of engine speeds.