The main bearings in this steam engine are made of poured babbitt metal. Bearings of this type are formed in place by loosely assembling the bearing caps with the crankshaft installed and supported at the correct assembly location. After everything has been properly located, the open gaps between the bearing blocks and the shaft are sealed with clay, and molten babbitt metal is poured in through the lubrication hole.
Once the metal hardens, it is trimmed and scraped to its final shape. Finally, before the bearing enters service, it is cleaned, well-lubricated, and "run-in", which is a process of slowly turning the shaft and allowing the bearing to develop a wear pattern that matches the microscopic contours of the shaft surface.
The bearings in this engine were in extremely worn condition and needed to be replaced, so I used a torch to melt out the old bearing material. Then, I sandblasted, painted, and reinstalled the caps. Once the crank has been rebuilt, they can be rebabbitted.
|Removing the babbitt|
|Ready for sandblasting|
|Sandblasted and ready for paint|
|Freshly restored bearing caps installed on the engine|