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Sunday, September 7, 2008

Getting Scale-Craft trucks in shape

Anyone who has tried to run any OO gauge models since 1937 has made some use of freight cars with Scale-Craft trucks. Close to half of the cars in my collection have these trucks. Those on the layout have been worked over to varying degrees to get them in shape.

By far the biggest problems are with the bolsters, both of the problems being illustrated in this first photo. On the left we have a bolster that has shrunk. I would say roughly ¼ of all the S-C truck bolsters I have show some evidence of this shrinkage. For this problem in reality there is no good fix; if the truck won’t roll put the truck on a car you don’t plan to operate and move on.

UPDATE: Now we have 3D printed S-C bolsters! These work great, more info here. 

The problem on the right is fixable. Note how the side frame is tipped in relation to the bolster. In his article “A Fix for Scale-Craft Trucks” that was published in the May, 1994 issue of The OO Road Bill Johann recommended the use of what he called bolster shims. These you would insert between the end of the bolster and the side frame, down in the pocket it fits in, to keep things square; the thickness will be in the .015-.025 range. This can help a lot, keeping everything square.

The central problem is many S-C trucks don’t roll well, and on a heavy car that is really a problem. Besides bolsters the principal problems are with the axle holes. These may need re-drilled slightly bigger and or deeper, Johann recommended a .070-.073 diameter drill. I use a #51 drill. You may want to also chamfer the holes and blow in some powdered graphite as well.

A secondary problem can be the bolster clip; the longer tab can interfere with the wheel sets. These Johann recommended trimming to a 30 degree angle, the part that can hit the flange.

Speaking of wheel sets, Scale-Craft marketed at least three distinct types of freight car wheel sets, two of which are illustrated here. By far the most common type is on the left, brass wheels with the split axle. Some examples of this type were made with steel wheels. This type of wheel will work very well if the gauge is right; use a NMRA On3/OO standards gauge and get them in line.

The type on the right has wheel sets that are not brass but rather are a type of plastic or Bakelite. The treads are slightly wider but this type seems to also track well. This type I think it is from very early Scale-Craft production but I really don’t know this firmly. Anyone with an un-built, very early kit out there that can confirm this? They are the same wheel shipped out in the lead truck of their 4-6-0 as well.

The final type is in the last photo, with a solid axle insulated on one side, from late Scale-Craft production. I tried to get a few of these in gauge that needed adjustment and ended up messing up the insulation, so be a bit careful with these.

[UPDATE: Actually, the insulation is fine! Now I know that Scale-Craft trucks are very sensitive to solid bolster axles, which can cause shorts due to the flex and play in the trucks. Also now the very early type of wheelset with plastic wheels makes perfect sense, it totally avoids any shorting issue for two rail use. With a further UPDATE being I avoid using the late wheelsets on the layout. The problem being that the tread width is typically under NMRA standards to such an extent that they derail constantly on my layout.]

In short most Scale-Craft trucks can be fixed to provide good service unless the bolster has shrunk, in which case it may not be practical to fix the truck.

UPDATE: Continue to this article for even more on tuning up Scale-Craft trucks.

2 comments:

Anonymous said...

Hi. One of my new cars [the C&NW #43502] outside braced box car seems to have Scale craft trucks mentioned above. It is a very nicely detailed car. What puzzles me is that there are two wires coming out the bottom of the car and going to homemade brass clips that attach to either side of one truck. The doors don't open so I can't peek inside to see if something is in there. I applied some DC power and saw no effect. I hope these trains run on DC. Would you have any idea what these wires might be? Thank you. Lon

John Ericson said...

I can't really answer this one, no idea what electrical thing might be in a boxcar. If it is one of the Temple Nieter cars, he was an electrical engineer by profession and could have had some special thing going on. In any case, it might work better to send me an E-mail or contact me via the Facebook page or to post the question to the Yahoo American OO group.