Abstract
In this study, an ultrasonic technique was applied for the measurement of vertical and axial load acting on implemented hub-bearing having two races, operating under non-rotation condition. Estimation of those loads was performed by the observation of echo height reflected from the interface between an outer ring and a ball. Reflection echo height at upper side of hub-bearing decreases since the supporting load of the ball is increased at upper side, when only vertical load WV is applied to the bearing through the tire. Meanwhile, the echo height at lower side of the bearing is increased up to the same quantity of variation observed at upper side, because the supporting load of the ball at lower side is decreased in contrast to upper side. When only axial load acts to this bearing, the relationship of load and echo height for upper, lower, front and rear sides shows quite opposite behavior for the ball existing at the wheel or body side. From these observed relations, individual estimation of the vertical and axial load becomes possible even if those loads affect to a bearing simultaneously. For instance, in case of the balls in upper side of bearing, the vertical load can be estimated from the averaged value of echo height for two balls locating at upper side, and the axial load can be estimated from the difference between echo height for each balls and average value mentioned above.
