Restoration of X-SP2479 continues to move forward although at a slow pace. We are about to reset the right side crosshead guides. The right side guides were found to be not parallel to the cylinder center as well as not equally spaced.

In addition to crosshead height, how much additional clearance should be allowed between the guides?

Thanks in advance.
John Ezovski

I take it the 2479 has Alligator Xheads correct? With anything on an engine, the tighter you set it up the longer it lasts (unless you are binding or do not have adequate tolerance for lubrication). The most important thing you can make sure of is the guides being perfectly parallel to the piston rod/cylinder bore. Second, it is imperative to have accurate measurements from the centerline of the bore to the guide bars so the xhead slippers can be machined correctly. I assume the xhead is babbitted in this case? Either way, I have set up xheads with a 32nd (about .031) of clearance which gives good service and is a long way from FRA maximum values. Another thing is to set up the xhead center line a 64th (about .015) higher than the cylinder centerline so the wear in period brings the xhead centerline down to the cylinder bore centerline. I am sure there are many other opinions on the subject, these are the philosophies I have used and found successful. Just be sure to set these up accurately and check them for binding. Can't wait to see another SP pacific in steam!

Best,

Stathi