Investigation of factors affecting the performance of pinion bearing for gear unit of railway vehicle

Abstract

If bearings for gear units of railway vehicles are damaged by seizing, parts of the bearings come off and damage the gear and the gear box, which may lead to the leakage of the gear oil and the defective rotation of the wheel sets. Tapered roller bearings are mostly used in the gear units in Japan. The sliding speeds at the contact surface between the roller end and the inner ring flange of the pinion bearings are higher than that of the gear bearings. In the pinion bearings, therefore, seizure may occur by metal-to-metal contact from inadequate lubrication between the roller end and the inner ring flange. In order to prevent seizure of the bearings and to improve the reliability of the gear units, it is important to clarify the causes of the inadequate lubrication and the mechanism developing from inadequate lubrication into seizure of the bearings. In this work, the effects of bearing rotational speeds and loads, gear oil temperatures and flow rates, and endplay (internal clearance of bearings) values on the performance of the bearings have been investigated by using a rotation testing apparatus for pinion bearings. As a result, it has been clarified that the heating value from bearings increase as the oil temperature decreases and as the oil flow rate increases. In addition, it has been found that the endplay value is greatly reduced when the rotational speed of the bearing rapidly accelerates to high speed under conditions where the temperature of the gear oil is relatively low.

Keywords

• railway vehicle
• gear unit
• pinion
• machine element
• tribology
• rolling bearing
• seizure
• gear oil
• endplay