The next step in refurbishing the driving boxes includes building up the surface of the hub face with babbitt, and machining it, as well as the crown brass.
Babbitt (named after the inventor) is an alloy used as a sacraficial bearing metal. The structure is made of small, hard crystals dispersed in a matrix of softer alloy. With use, the matrix erodes and provides a path for lubricant.
Babbitt can be easily melted in the shop, and then poured into the mold. In this case, the hub face of the driving box was first grooved to increase the surface area, and a block mold formed around the surfaces to be babbitted.