Damage detection of bearing in gear case by using piezoelectric element incorporated in hanging rubber for gear case of rolling stock (Evaluation of defection performance by bench test)

Abstract

A gear case used at a bogie of a rolling stock is an important part to pack a small gear and a large gear that pass the driving force from a main mortar to a wheel. An axle, to which the small gear and the large gear connect, is housed in a gear case through an axle bearing for rotation. The defect of the axle bearings can affect the running safety of rolling stock. In this context we investigate a sensor using a hanging rubber, which can detect of damage of axle bearing in gear case. The hanging rubber is used as a fixing device, which attaches the gear case firmly to the bogie frame. By using hanging rubber for sensor, it can be easily installed for bogie. In addition, the loss of the sensor installed on the bogie and the risk of impact with flying object can be reduce. The sensor using the hanging rubber is incorporated with a piezoelectric elements. The piezoelectric elements can convert mechanical energy to electric energy, and vice versa. The defection of axle bearing in gear case can be detect by the electric signal generated from piezoelectric elements. The rotation test by rotation testing machine of gear system with sensor using hanging rubber is carried out. As the result of rotation test with damaged and normal small gears, it is confirmed that the damage can be detected by amplitude of electric voltage from piezoelectric element when the rotation speed is higher than 50km/h. In case of the rotation speed is lower than 50km/h, the damage can be detected by the frequency analysis of time wave.