Hey gang, I have a small layout 2'x4', with a loop of track near the edges. Built with Atlas code 80 flex. The corner radius is around 10". In a couple of spots, my locos are struggling - a small steamer pops the leading pilot wheels off the rails (but only in one direction!) and another diesel loco tends to bind in the same spot (mostly in the other direction). I know 10" curves are tight - no need to debate that here. I use my NMRA gage to measure track spacing, and it seems within range, but the symptoms just listed suggested that the track is just slightly out of gauge. What I'd like from you hear are ideas for fixing the gauge of the track. How can I increase the space and hold in the right spot permanently? Thanks.
If the gauge seems to show track is within range, then it would be interesting to also know more about the locos you are using- Could you tell us? It may be they are the issue and ten inches is just not suitable for their operation.
Peter, it's possible the wheels/trucks that are derailing are being blocked from turning completely when they try to follow the 10" curve. You say this only occurs in one direction, so I would look to see if anything is binding or blocking the wheel/truck from turning in that direction. With the pilot wheels, it may be something as simple as a piece of flash or casting that needs to be filed very slightly and carefully to allow more clearance. With the diesel truck, it's possible that the gear tower is binding with the frame. Like Ken says, a 10" curve may be at, or beyond these locos' limits. Also without having the locos in our hands, it's difficult to diagnose. I doubt if the track is out of guage because that would effect locos and cars alike, and in both directions. Is there a local hobby shop nearby that you could take the locos for discussion?
Had similar problems with my 2x8 layout with 11" radii at the loops. Some engines would derail only the leading wheels of 6-axel diesels in only one direction. Checked the trucks of the problem guys but found no issues, although "binding gear train" wasn't checked. Eventually problem solved by re-laying the track very carefully. Believe the track along the curve was tilted a little differently in the region of the join between the Peco c55 flex used for the easement lead and the Atlas c80 fixed curve pieces. Big tip is to not ballast until all this stuff works well. Needed to get the joins of different track perfectly mated in 3 dimensions. Very fiddily. Good luck.
Wheel gauges is my first check point and also for any imperfections on those wheels. Then it is back to carefully running those same locos over the same area of track to carefully identify exactly where the wheels leave the track and marking that spot. Since most small steam will negotiate 9 and 3/4 and some three axle diesel also I will assume that is not the issue and think more toward the track. Flex track can be funny at times when bent into sharper radiuses, and a slight inconsistency in the rail sidewall thickness could have an area smaller than an inch in length that is just slightly out of gauge at the railhead, and only on the one side. Once you have IDed the spot where the derailment occurs then careful checking with the gauge may determine that although the base is in gauge the railhead may not be, or there could be a slight kink in a very small area. If it is the rails then there may be a couple of options. First to replace the flex track section. Next would be to cut out and replace the section with a piece of six inch fixed 11 inch radius track if there is room in that area and then simply tie in the rest of the flex track to that. You would be coming into the 10 inch and then widening to 11 inch and back to 10 inch.
On long diesel trucks that are quite rigid with no lateral play like the Kato PA, a tight radius even if it is in gauge, can cause problems. A wider than normal track gauge can be helpful in very tight curve situations. Atlas Code 80 flex track has a tendency for the top of the sliding rail to lean toward the outside of the curve. If it is placed on the inside of a curve it will usually give you a tighter gauge and if on the outside of the curve will yield a wider than standard gauge.
Thanks Russell - I don't know why Atlas still recommends that the sliding rail on flex track go to the inside of the curve. It has been proven time and again that this narrows the gauge. It would be interesting to know if that is how the 10 radius curve was laid in this case. Al
It's not your imagination. The 'slop' in Atlas C80 Flex is perfectly capable of tightening gauge, particularly if it is warmer now then when the track was laid - even a small change in rail expansion will expand the sliding rail and attempt to pinch it tighter somewhere. It's going to move. Only question is where. I banned the 'loose rail' C80 flex a long time ago because of it. But here's some tips.... OFF the curve (on a section of straight(er) track).... you can cut an expansion gap with a dremel, and solder a jumper wire across it. Ideally you'd have a rail joiner here and if you're not ballasted, put one in even if it means temporarily lifting and relaying the track. If it is already ballasted, it should hold without a joiner. It will kink if you try this on a curve. Object is to take that expansion stress off the rail. At or during the same time....you can take the narrow spots, and with a track gauge - spread the rails and hit the spike areas with ACC. That will hold the rail and that spot but tends to chase the problem elsewhere. If you've decided to relay the curve - I'll tell you that I've decided that I do better with sectional track on all curves 11" and tighter. I solder them up, just no longer than 48". If you need to adjust in and out for spirals or other adjustments, cut some ties loose underneath like flex track, but the ties are nice and tight on sectional and won't pinch down on curves from movement. Or, you can also end up evolving where I did....using Peco C55 flex instead of Atlas C80. The overall track is about the same thickness, the C80 switches can fit in with it pretty well if geometry is a problem, and Peco C55 is about as tough and rigid as it gets. But it gets pretty difficult to do a consistent curve with it tighter than 11", it fights back pretty well and you'll need to spike it down hard.
