INVESTIGATION OF INSTABILITY, DYNAMIC FORCES, AND EFFECT OF DYNAMIC LOADING ON STRENGTH OF CAGES FOR THE BEARINGS IN THE HIGH PRESSURE OXYGEN TUR60PUMPS FOR THE SPACE SHUTTLE MAIN ENGINE

摘要

Calculations were made of the magnitude of the ball/cage forces resulting from combined radial and axial loads. With an axial load of 4400 N (1000 lbs), the ball/cage pocket clearance is suffi¬cient to accommodate the ball excursions produced by ball speed vari¬ation with radial loads to 3600 N (800 lbs). With loads beyond 3600 N (800 lbs), cyclic ball/cage forces are developed, the magnitude of which depend on the ball/race coefficient of friction. With a coefficient of friction of 0.2, the ball/cage forces are approximately 220 N (50 lbs). Although loads of this magnitude are well below an experimentally determined cage working strength of 1300 N (300 lbs), they may be sufficient to cause cage wear. On this basis, cage fail¬ures from overloading would appear to be the result of cage instabili¬ties or excessive bearing overloads rather than from loads applied in normal operation.