Proposal for grease replacement system for traction motor bearings

Since replacing the lubricants used on traction motor bearings of railroad vehicles is a difficult and time-consuming task, extending the lifespan of the lubricant would be a useful development. Although an interim greasing method has been adopted as a way to extend the lifespan of lubricant for some types of induction traction motors, this method requires leaving empty space to refill additional grease. However, this empty space can mean that there is insufficient lubrication during the initial stages of motor operation. This paper presents a new mechanism that enables the refilling of grease without the empty space. The new method allows the deteriorated grease to be flushed out and replaced with fresh grease without the need to leave unfilled space adjacent to the bearings. Tests suggest that the lubrication lifetime is maximized when the greasing operation is performed about one-quarter of the way through the standard lubrication lifetime. Full-scale bench tests show that the new greasing mechanism and optimal greasing periodicity significantly extended the lubrication lifespan.