Experimental Analysis and Study of Wear of Crankshaft Bushing under Variable Conditions

In crankshaft bush bearings, especially at the journals, are very loaded elements. For their proper functioning it is necessary to define carefully the working conditions, where the quality of oil is one of the most important factor. From the aspect of the working conditions of journal bearings it is important to ensure a minimum change in oil viscosity. Selection of lubricating oil from the standpoint of physical characteristics, primarily are approximate viscosity, has an important place in the area of reducing friction losses in journal bearing and increasing bearing efficiency. This paper deals with the impact of lubricating oil viscosity on the working conditions of hydrodynamic CuPb24Sn4 journal bearing to determine effect of variable load, speed and viscosity of lubricant on depth of wear of lining thickness (dw) of CuPb24Sn4 material bush used in indigenously designed Test Rig which is widely used as bush material in automobile engine. The wear of lining thickness occurs symmetrically at the highest temperature zones for all 3 samples. The evaluation of wear is tested under variable load, speed and viscosity of lubricant. The designer has to select the Viscosity Index as per the load, surface finish, clearance ratio, d/D ratio and length of bearing. The viscosity of lubricating oil is depend on shear rate, that the fluids do not have single value of viscosity over the range of shear rates. As the shear strain rate increases the viscosity of fluid is diminishing. The relationship between depth of wear of lining thickness (dw) versus variable load, speed and viscosity of lubricant is established by using the experimental results and regression model.