Bob, I took a quick look at both the Trainmaster and the SD60. It appears the vertical travel distance of the middle axle is less than the outer axles. I don't understand the dynamics but it would seem to make truck somewhat unstable because it would want to teeter-toter about the center axle. The weight of the loco coming down through the kingpin on to the center wheel might make it more so. I would think (my simplistic mechanical mind at work) that giving the center wheel more give would allow the weight to distribute to the outer axles making a more stable triangle arrangement.
The SD60 axles are equally spaced. The Trainmaster's are not. When rocking the truck frame back and forth while on the track, one of the wheel sets lifted further off the rail than the other (I think it was the more distant axle). All this makes me wonder whether you should to play with the adjustment of the top nut on the kingpin. Happy Thanksgiving all! Ben Trousdale --- In [email protected], Bob Werre <bob@...> wrote: > > Ben & Guys, thanks for the advice. When you look at the truck castings > from the side--you will notice that each half has three bulges, one > under each axle. Those bulges house the place where those springs > reside. The two outside bulges are deeper (higher) than the center > one. Also I measured the depth of the outside vs the middle hole and > they are different. I used the middle part of my caliper to drop down > into the hole, but because much of the frame is curved any measurement > would be somewhat inaccurate for the quick work I was doing. > > Since I purchased this unit used, the prior owner could have fooled with > or replaced the original springs, but I can't be sure of that. It is > also possible that AM used different bearings for that middle axle where > the hole might be offset or smaller on both upper and lower surfaces. > However both of these possibilities don't make sense from a > manufacturing point of view--why make them different? > > I do have some AM PA's but they have a rigid frame so that's no help. > My much beloved U-boats have the sprung trucks but they are only two > axles and they seem to run just fine--and I might add very quietly. > > Bob Werre > > > On 11/23/11 1:15 PM, pickycat95 wrote: > > > > Bob, > > I have several 3 axle AM locomotives including the Trainmaster with > > the sprung axle bearings. I've never had the issue of which you speak. > > I would carefully inspect the area where the bearing sits to see if > > there is something (dirt)imbedded in the gobs of grease that gets put > > into these things at the factory that might be causing the bearing to > > ride high (or low if you will). > > Ben Trousdale > > > > P.S. I've been away from the list for a while causing trouble on SSTOT > > list. > > > > > > [Non-text portions of this message have been removed] > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/S-Scale/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/S-Scale/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
