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In two wheelers the front suspension system is mounted on chassis by two steering bearings which are lubricated ball type angular contact bearings with significant radial force components. These bearings are designed to withstand maximum vehicle loads for target durability. Maximum load carrying capacity depends on the number and size of the balls, bearing size and material. For target durability with designed load carrying capacity, the ball contact pressure, bearing preload plays a major role as compared to other design parameters. Geometry parameters and maximum load defines contact pressure for given bearing design. But in two wheelers due to nature of usage and road conditions, the peak loads are dynamic and geometry based design calculations may not yield the most optimal bearing design. In this work the bearing ball race profile design is optimized by using dynamic bearing contact profiles by using nonlinear Finite Element Analysis.

Typically the velocity dependent hydraulic damper characterization is done using a sinusoidal input to the damper. Damping force vs. displacement and velocity plots are used to represent the damping behaviour. It was observed that the dampers exhibit equal damping characteristics using this conventional method, shows a significant difference in ride comfort levels of the vehicle. This behaviour primarily arises due to the variation in response of the damper with the excitation frequency. On actual riding conditions, apart from harmonic loads, the suspension experiences impact loads that affect the damping generation characteristics. So the damper also needs to be characterized with variation of frequency ranging from 0.5 Hz to 25 Hz. Due to the limitations of damper stroke and input frequency, complete characterization of damper is not possible with sinusoidal input test rig.

Damper lag and hysteresis are important parameters affecting the dynamic response of the hydraulic shock absorbers. The response of the suspension unit to road excitation strongly influences motorcycle ride comfort. Overall ride comfort of a motorcycle, under various operating conditions, is a result of very complex system dynamics, where the damper dynamics has a major share. This makes it imperative to include damper lag as a critical parameter for ride comfort optimization. Analytical models are available to predict the dynamic behaviour of a hydraulic damper, however their ability in capturing the lag and hysteretic characteristics is limited. Capturing such dynamic phenomenon through mathematical modeling can become very intricate and involved, thus making the task of analysis and simulation of ride comfort further complex. Literature available on experimental research in establishing the effect of damper lag on overall ride comfort is found to be very limited.