Howdy all,
Week before last, we discovered a hub crack on the #4 right side wheel center on Polson 70 at the Mt. Rainier Scenic Railroad. This is a cast iron wheel center, and as you can see in the photo, the crack had just begun at the edge of the keyway. Though banding the hub is a legal repair, I did not feel it would be effective in this instance. Luckily, a hub crack repair was undertaken by George Sapp at Railtown 1897 on the Sierra 3 using a "metal lock" product. After speaking with George and hearing of his success, we elected to use this method which was provided to us by a company called "locknstitch." I have no affiliation with the company but can say I was pleased with the product, and figured others might be interested in its uses for hub or saddle repairs.
The product is basically a series of holes drilled in sequence to form a multiple dog bone opening. This opening is filled with 1/4" strips of corrosponding pattern which also help to draw the crack closed. Photo two shows the hole pattern which was completed in a bit less than a day to a depth of 3.250" using a mag drill and the drilling jigs provided. Photo three shows the cavity filled with the lock strips and peened so as to expand the strips into place. The final step was to drill, tap and insert drawing stitch pins at the four corners of the lock, and the rest of the crack. You can see an open hole with counterbore ready to tap and insert the last of these pins. These stitch pins have a thread form which draw the metal together rather than spread.
After a weekend of service on our steep grades, with plenty of rain, and downed leaves with a "couple" wheel slips, the repair is holding very well. I hope this might be of some use to others presented with a similar problem!
Stathi
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