|20/35||A-3 - Tightening bolts during truck side frame assembly Return to MSR&LHA Home page|
Looking good, but will it remain straight? One of the two arch bars we were working with this weekend was torqued out of shape longitudinally, which caused the side frame to wind, or twist, as the bolts were tightened. This condition was corrected by careful press work. On the other side frame, which would not TWIST as the bolts were tightened, the both ends of the new bottom bar would bow upwards as the bolts were tightened. After much scratching of heads and other things, it was determined that the heights of the arch bar ends were both taller than the bolt-up height of the bolster pedestals. But things get stranger yet, as the two ends of the arch bar were of differing heights! Eventually it was figured that one end needed a 1/4 inch shim above the journal box pedestal, and the other end required a 3/8 inch shim for the bottom bar to remain straight after the bolts were drawn tight. All told, without exaggeration, these two side frames were put together no fewer than nine or ten times for tweaking before we were happy with them. Things like this make some people question what we did all weekend, but in the long run, attention to many such unseen details will pay off.
Photo by Bill Liebman