General Discussion (Model Railroader)

I have 4 engines, and all but one run fine. The one in particular keeps shortening out on curves, and sometimes in the straightaways too. Is there something different, possibly wheel distance issue?  I am using code 100 track, 15" curves. Thanks in advance, Carl

What type of engine is it - steam or diesel, how many axles etc?? What are the other engines that run OK??

15"R curves are VERY sharp if you're in HO scale, most HO stuff is set to handle only 18"R curves as a minimum (and would do better on much larger curves) so it could be the backs of the wheels are coming in contact with something on the frame perhaps or something like that...although that wouldn't explain the problems on the straight track??

I agree, 15" radius is extreme in HO in all cases that I can think of, except perhaps in transit/interurban or backwoods tracks using Heislers/Climaxes/Shays.  But even so, you are having things swing sharply to stay in the rails on those curves, and depending on the design of the engine, and/or its condition, you could very well have a short.  Drivers sliding to one side at the apex of the curve (from the driver wheelbase's point of view) so far that they touch the frame, rods touching something, worn wires by this time, worn/slipping/dangling wipers, paint that normally insulates at a contact point is now worn through...the list goes on. 

You say it sometimes happens on tangent track?  This suggests something worn and coming into contact with charged metal either in the drive or possibly in a wire/wire harness.

Is it an older Atlas diesel by any chance? Their couplerboxes are not insulated from the frame (used as the ground), so they are essentially connected to one rail. On a tight curve the couplers can swing far enough for the trip pin to contact the opposite rail. They were designed with plastic horn-hook couplers in mind, but the Kadee couplers (not invented back when the locos were produced) are metal and conduct electricity. Rail A through trip pin, through coupler to grounded frame, to Rail B... ZAP!

Of course, there are many more likely problems... I'm just stating one that you might not think of...others know much more than me about other problems and could help better there.

I had a previously reliable loco (Ken Kidder-imported 0-8-0T) start shorting out on tangent tracks connected by curves far wider than it was designed to handle - problem traced to a loose driver tire that was intermittently contacting the siderods.  A dab of CA took care of that little 'opportunity' and flawless operation is once again a norm.

Am I the only one who operates the Mantua/Uintah 2-6-6-2T on prototype radius (68 degree!!!) curves.  The TTT mainline has curves of 350mm radius, but the articulated has actually tested down to 300mm.  OTOH, all of my JNR locos and a lot of longer rolling stock is embargoed - confined to the 610mm (24 inch) radii of the JNR mainline.  The rest of the TTT locomotive roster consists of short-coupled teakettles with roller skate wheels for drivers, locomotives for which 14 inch radii are not a challenge.

Chuck (Modeling Central Japan in September, 1964)

Thanks everyone for your suggestions and ideas, it appears that either, one, my engine is worn out, or two, my curves may be two tight for the job I am needing. Thanks, Railroadinmedic

 I only have four HO locos: a Kato NW-2, an IHC 2-6-0 Mogul, a Bachmann 0-6-0 switcher, and a Kato RS-2. The first three all run fine on 10" radius curves. The RS-2 requires a 15" radius, on which it runs fine. As a general rule, the shorter the loco and the wheelbase, the tighter the curve it will negotiate, although there are exceptions.

If your loco is shorting out, it seems like the problem would be something other than small radius curves. OTOH, if it was derailing, that would be different.

tomikawaTT:

Am I the only one who operates the Mantua/Uintah 2-6-6-2T on prototype radius (68 degree!!!) curves. 

Chuck (Modeling Central Japan in September, 1964)

You might be!  68 degrees equals how many inches in HO radius?

HarryHotspur:

 

You might be!  68 degrees equals how many inches in HO radius?

A little over 12".

Degree to radius chart