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Ductile iron has traditionally been the material of choice for differential housings on rear wheel drive axles because of it's durability and low cost. There is a trend to use Aluminum as a differential housing material to reduce vehicle weight and improve fuel economy. One must be careful to account for the differences in material properties of the two materials when switching to Aluminum. Careful consideration of bearing fitting practice, pre-load setting procedure, and in some cases, design to achieve optimum axle performance is necessary. This paper is written as a bearing guide for differentials with Aluminum housings.

Fatigue life of the 6206 deep groove ball bearings has been evaluated under various thin lubricant film conditions. Endurance testing demonstrates that the fatigue life is remarkably longer than previous formal experiments. In addition, examination of flaked areas showed some to have subsurface origins, even after testing with extremely thin lubricant films. Longer fatigue life has been attributed to improvements in bearing steel quality, as well as improvements in the surface roughness of the ball bearing raceways. With thin lubricant films, the film parameter Λ, and the roughness profile have a greater influence on ball bearing fatigue life. Qualitative analysis of the rolling contact surfaces of some of the bearings after test has been carried out, and the formation of oxidized and carbonated films has been detected. These films can be considered to be contributors to longer fatigue life.

Many types of variable speed accessory drive systems have been researched and developed, but none have been adopted in a production car1,2. There has been an increasing demand on the accessory drive system due to the adoption of new accessories in passenger cars. Along with the increasing demand on the system, nothing can be done which would decrease fuel economy. So, the efficiency of the system must be improved. This has caused renewed interest in variable speed accessory drives. A compact V-ribbed (serpentine) belt CVT system for accessory drive (called CVAD: Continuously Variable Accessory Drive System) has been developed3. By applying the CVAD for the accessory belt drive system, fuel savings, increased vehicle performance in acceleration, noise reduction, increased life of accessories and V-ribbed belts, and a reduction in the size of accessories are possible. The performance of a prototype variator, the principal component of the CVAD, has been evaluated.

The objective of this study was to investigate a method to predict brittle failure of silicon nitride ceramics in rolling contact. Fracture mechanics was used to predict crack propagation. Cracks in ceramic rolling elements, like steel, propagate after cyclic stressing in rolling contact. Failure occurs when a crack propagates unstably, or when the stress intensity factor exceeds the fracture toughness. Rolling life was predicted analytically for thrust type rolling contact under dry friction conditions, and compared with experimental results. The experimental lives were distributed near the predicted life curve based on 50% cumulative probability of failure. Consequently, the prediction of rolling life using fracture mechanics is found to be valid to predict reliability against brittle failure of silicon nitride ceramics. From this analysis, the following characteristics were identified as important to maximize resistance to brittle fracture: 1. Short initial crack length 2.

Operating temperatures in many bearing applications exceed 100 °C. Conventional bearing steel (SAE52100,SAE5120,Etc.) will begin to experience a reduction in life due to dimensional instability, and reduced surface hardness, at these temperatures. High speed tool steel (such as AISI-M50) can operate in temperatures up to 300°C but is very costly. SAE52100 can be heat stabilized up to 300°C to improve the dimensional stability, but this process can severely decrease the surface hardness and fatigue life. There are many applications where the high operating temperature is greater than 100°C but less than 200°C. A new material has been developed, based on SAE52100, with improved dimensional stability, and surface hardness, for this medium operating temperature range.

Because of their smooth torque transmission, high efficiency, low noise, and high running accuracy, planetary roller type traction drive units are becoming a common, widely used a speed increaser that can achieve rotational speeds of ten thousand RPM, or a speed reducer that has very small angular velocity fluctuation. When it is utilized as a transmission, particularly grease lubrication, traction damage is caused by excessive torque load and lubricant deterioration. This paper examines traction damage caused by torque load, using a machine tool high rotational speed planetary roller type traction drive unit with grease lubrication, and the practicality of an oil film monitor using electrical resistance, and direct current power source for monitoring the oil film condition of traction surface.

Recently, the performance of automobiles and industrial machines has improved remarkably. Bearing performance requirements have also increased. One of the performance requirements for bearings is increased bearing life in contaminated lubrication which contains wear debris. The bearing failure modes in contaminated lubricant are peeling caused by debris, and/or surface-initiated flaking caused by dent. Bearing life is increased by optimizing the surface hardness and the amount of retained austenite. Based on these results, a new bearing was developed, which showed ten times longer life than conventional bearings in contaminated lubrication.

High speed precision ball bearings, like those used in machine tool spindles, can have serious problems associated with spin or gyroscopic moment of the rolling elements. The use of low density, silicon nitride ceramic rolling elements reduces these problems. This report presents performance test results of bearings with silicon nitride balls, and steel balls, in a high speed turbine application, using oil jet, and oil mist lubrication methods.