The presence of the oscillating motion in a mechanical system, is vital in terms of the service life. Because the machine elements are under effect of fatigue due to the oscillating motion. The service life of the bearings which are in the forefront among the machine elements subjected to oscillating motion, can be calculated via an equation that depends on several variables, one of which is basic dynamic load rating (C). In this context, basic dynamic load rating (C) is one of the most important factors on estimating the service life. One of where bearing applications used in, is universal joint of driveshaft. A bearing on a universal joint consists of needle roller elements having larger contact area compared to the ball elements. Universal joint bearing is mounted in a bore on a component called yoke part, and so yoke part supports the bearing. In the calculation of basic dynamic load rating for universal joint bearing, effective length of the rolling element is the key factor. In this paper, a new approach to determine the effective length of rolling element used in closed end needle roller bearings of driveshaft has been investigated analytically and the effect of the said approach on the basic dynamic load rating and bearing life has been revealed in terms of ISO 281.

Usage of friction welding method on the joints provides many advantages such as cost reduction, weight reduction and higher quality. The yoke shaft produced by rotary friction welding (RFW) involves a yoked part and a hollow round bar which are welded to each other. And so, no additional drilling method used in the way of removing material from the centre of the yoke shaft, is required to reduce the weight. The weight is inherently reduced thanks to hollow round bar used in RFW method. It is possible to use a friction welded yoke shaft in a wide range of wall thickness by removing material from the shank diameter for different applications. At this point, the key factor is strength of the friction welded yoke shaft with reduced wall thickness on the shank diameter. The aim of this study is investigation the effect of the reduced wall thickness of a yoke shaft produced by RFW on the strength. For this purpose, yoke shafts were manufactured by using RFW and consecutive processes such as turning and millings to reduce the wall thickness. The specimens in different wall thickness were tested to determine the strength. Additionally finite element analyses (FEAs) were implemented for each variation of the specimens and compared with the test results. As a result, it was determined that yoke shafts with reduced wall thicknesses, which were produced by RFW and then consecutively machining operations to obtain a specific wall thickness, can be used in drive shaft manufacturing securely.