No abstract

The results of an analysis of the effects of spur gear size, pitch, width and ratio on total mesh power loss for a wide range of speed, torques and oil viscosities are presented. -The analysis uses simple algebraic expressions to determine gear sliding, rolling and windage losses and also incorporates an approximate ball bearing power loss expression. The analysis shows good agreement with published data. Large diameter and fine-pitched gears had higher peak effi ciencies but lower part-load efficiencies. Gear efficiencies were generally greater than 98 per cent except at very low torque levels. Tare (no-load) losses are generally a significant per centage of the full load loss except at low speeds. Key Words (Suggested by Author(s))18 Distribution Statement ABSTRACTThe results of an analysis of the effects of spur gear size, pitch, width and'ratio~on total mesh power loss for a wide range of speeds, torqdes' and Oil viicoslties are presented. The axalysis-uses simple alge braic expressions to determine gear sliding, rolling and windage losses and also incorporates an approximate ball bearing power loss expression. The analysis shows good agreement with published data. -Large diameter and fine pitched gears had higher'peak effliciencies but lower part-load efficiency.Gear efficiencies were generally greater than -98 percent except at very low torque levels. Tare (no-load) losses are generally a significant per centage of the full-load loss excepd at low speeds.-'

P a r t l c u l a r emphasis i s placed on h i g h c o n t a c t r a t i o gearing ( c o n t a c t r a t i o s g r e a t e r than two). Despite t h e i r h i g h e r s l i d i n g v e l o c l t i e s h i g h c o n t a c t r a t i o gears can be designed t o l e v e l s o f e f f i c i e n c y comparable t o those o f conventional gears w h i l e r e t a i n i n g t h e i r advantages through

Ball bearings were fatigue tested with a noncontaminated MIL-L-23699 lubricant and with a contaminated MIL-L-23699 lubricant under four levels of filtration. The test filters had absolute particle removal ratings of 3, 30, 49, and 105 microns. Aircraft turbine engine contaminants were injected into the filter’s supply line at a constant rate of 125 milligrams per bearing hour. Bearing life and running track condition generally improved with finer filtration. The experimental lives of 3- and 30-micron filter bearings were statistically equivalent, approaching those obtained with the noncontaminated lubricant bearings. Compared to these bearings, the lives of the 49-micron bearings were statistically lower. The 105-micron bearings experienced gross wear. The degree of surface distress, weight loss, and probable failure mode were dependent on filtration level, with finer filtration being clearly beneficial.