Edited 12 Jan 2022 17:48, 4 months ago, edited by c3526blue

Was doing a search for other stuff and came upon this post from Rod dating back to 2019. Hope I'm not put in the naughty corner for resurrecting an older post, and hope my contribution is positive, considering it's my first.

Just in the process of building a layout mainly using Peco code 83 track, but the geometry in one particular place required the use of a right hand Tillig curved point PZ85373. And yes, I was experiencing the same problem as Rod, the pony bogie of my Eureka 50 class kept derailing as it passed the frog when travelling in the direction of the point blades. Was quite frustrating as the loco negotiated all Peco code 83 curved points perfectly.

First action was to remove the pony bogie spring which did slightly improve operation over the point momentarily, but the issue soon returned. I suspect the action of removing the spring did improve traction, so I left it out.

The actual problem was caused by the inside pony bogie wheel fouling on the inside front of the cylinder, and in turn being pushed over the check rail, causing the outside wheel to strike the frog. I gently filed about .020" (.5mm) away from the contact area, which didn't detract and all was good.

Funnily enough the leading bogie on the 60 class then started derailing at the same Tillig point, boy, Tillig were about to be the first points into space. Then I noticed the inside detonator amplifier pipe was out of its socket and fouling the bogie wheel. Phew!!

The inside radius of that particular Tillig point is a tad over 500mm.

Cheers, Ray

Your experience with that Tillig point is understandable.  The 85373 has nominal radii of 543mm and 934mm for inner/outer portions respectively.  Curved points can and usually are very problematic on the inner curved portion and become worse as the radius reduces.  I even avoid using the Peco SL-(E)86/87 and 186/187 even with a nominal inner radius of 762mm.  

Many modern locomotives, such as the D50 and AD60 (both from Eureka) are built to fine tolerances and have trouble with less than perfect or most ordinary trackwork.  Recommended radii for these locos as I understand it is 605mm or 24".  The Tillig has a radius smaller than 605mm and hence the problems that have arisen, not even taking into account the issues of double curved pointwork.

I have experimented with the AD60 (as an example) and found it will negotiate Peco 3rd Radius (505mm) curves, but not Peco 2nd Radius (438mm) curves.  It must be driven very slowly and on close observation binding of the leading wheelset against the rear of the cylinders is apparent and as a consequence the outer wheel can be observed trying to climb over the outside rail.

You have made some modifications to your D50 to overcome similar problems and can replicate this solution on the AD60.  This addresses the symptoms but not the cause.  The cause is trying to make models designed for larger curves negotiate tighter curves than their design allows.

Happy tracking,

John P