Modern Multipurpose Gear Oils and How They Got That Way

The development of multipurpose gear lubricants is traced from the time of widespread use of hypoid gears in the late 1930’s to the present. The important role of the military requirements and the cooperative work of gear designers and gear oil compounders in the Coordinating Research Council is related. Some of the possible reasons for the differences of opinion that have existed in the past are pointed out and explained in terms of minor variations in test conditions that may exert a major effect of the performance rating of the gear lubricant.