Problems with Peco curved turnouts?

[RobertInOntario]

In the past, I've had problems with curved turnouts, even with Peco ones which are supposedly the best quality.

I'm working on a new, small layout and I've re-used one of my older curved Peco turnouts on it. Most of my locos and coaches pass through them OK except for one of my tender-drive British locos & 1-2 of my coaches also derail when they pass through them as well. The frog area seems to be the worst area.

It's possible that this older turnout is damaged so I'm wondering if I should simply replace this turnout by buying a new one. Or, have other folks had trouble with Peco curved turnouts? Maybe I'd be wasting my money and should simply revise the layout plan so it doesn't use any curved turnouts? BTW, this curved turnout is placed on a very flat surface, so I doubt that any unevenness is causing these problems.

Thanks,
Rob

[Selector]

It is very likely an unfortunate confluence of factors. For example, maybe your wheel gauge is just a bit close to marginal, and the position of the guard rails (or the wings) leaves too much slop for the axle to track accurately with the flanges doing the work. Sometimes placing a thin plastic shim, say 8 thousandths of an inch or a bit more, on the inside face of the guard will prevent uneasiness at the frog.

The other thing is that curved turnouts are msomewhat tighter in radius on the inner route than the manufacturers would have you believe. This is particularly true with the Walthers/Shinohara curved turnouts. I can't say about the Pecos because I have no experience with them.

-Crandell

[nachoman]

Since it is only a few pieces of equipment that have problems, check the gauge on those wheelsets. Even wheels slightly too tight will cause problems. Are these engines/coaches only derailing when traveling through one leg, or through both legs of the turnout? If they are only derailing through the tighter radius, maybe that radius is too tight for those pieces of rolling stock.

[RobertInOntario]

Since it is only a few pieces of equipment that have problems, check the gauge on those wheelsets. Even wheels slightly too tight will cause problems. Are these engines/coaches only derailing when traveling through one leg, or through both legs of the turnout? If they are only derailing through the tighter radius, maybe that radius is too tight for those pieces of rolling stock.

Thanks for these responses. Yes, it's only the tighter (or inner_ curve that's the problem. Also, the tender-drive loco only derails when traveling in one direction through the tighter curve -- when it passes through the curve coming from the other direction, it's fine!

The coaches (that I mentioned) have had 1-2 problems elsewhere on the track so I do think there could be gauge problems with some of their wheel sets. But the loco is usually a good runner so I'm not convinced (yet) if it has a gauge problem. BTW, it's the tender that is the worst offender.

Thanks, Rob

[Russ Bellinis]

Since it is only a few pieces of equipment that have problems, check the gauge on those wheelsets. Even wheels slightly too tight will cause problems. Are these engines/coaches only derailing when traveling through one leg, or through both legs of the turnout? If they are only derailing through the tighter radius, maybe that radius is too tight for those pieces of rolling stock.

Thanks for these responses. Yes, it's only the tighter (or inner_ curve that's the problem. Also, the tender-drive loco only derails when traveling in one direction through the tighter curve -- when it passes through the curve coming from the other direction, it's fine!

The coaches (that I mentioned) have had 1-2 problems elsewhere on the track so I do think there could be gauge problems with some of their wheel sets. But the loco is usually a good runner so I'm not convinced (yet) if it has a gauge problem. BTW, it's the tender that is the worst offender.

Thanks, Rob

You mentioned that the tender drive loco only derails when passing in one direction. Which direction is that? Is it derailing when approaching from the frog end or through the points? I'm going to guess it is picking the points. It may be either a small gauge problem with the loco, or a problem with the point on the tighter of the 2 radii. If you can run it through really slow and see what is happening, you might fix it with just a bit of work on the point or a bit of a shim on the guard rail.

[RobertInOntario]

You mentioned that the tender drive loco only derails when passing in one direction. Which direction is that? Is it derailing when approaching from the frog end or through the points? I'm going to guess it is picking the points. It may be either a small gauge problem with the loco, or a problem with the point on the tighter of the 2 radii. If you can run it through really slow and see what is happening, you might fix it with just a bit of work on the point or a bit of a shim on the guard rail.

Thanks, Russ. I might try correcting this then by adding a shim of 8 thousandths of an inch to the guard rail. Rob

[BR60103]

Rob: Take your vernier calipers and measure the back-to-back on the axles that derail. The minimum you should get is 14mm, 14.5 is better. If it's more than that they need to be squeezed. Also check the distance of the check rails/guard rails that they go through. Peco have changed their flangeway widths over the years.
Spin the wheels to see how much they wobble.
(Lee Valley sells a batch of vernier calipers fairly cheaply. I bought a really crappy one in the $ store for $1 -- it bangs about in the toolbox.)

[shortliner]

Regarding your problem with the coaches on the smaller radius of the curve - Check that your bogies have enough swing - I have some 57 foot Boxcars that weren't happy doing that, and discovered that the bogies swing was being limited by the coupler boxes - the back of the wheel was catching the back edge corner of the coupler box - a small trimming job on the back corners of the coupler box has cured the problem. Regarding the tender - check your back to backs, but also check that the curve radius isn't too tight for the fixed wheeelbase of the tender, which will prevent it from taking the curve properly. A possible cure might be to remove the flanges on the centre set of wheels - if there is no other way of solving it - I know that some fixed wheelbase 0-6-0 and 0-8-0 locos also have this problem and will only work happily on larger radius curves

[RobertInOntario]

Regarding your problem with the coaches on the smaller radius of the curve - Check that your bogies have enough swing - I have some 57 foot Boxcars that weren't happy doing that, and discovered that the bogies swing was being limited by the coupler boxes - the back of the wheel was catching the back edge corner of the coupler box - a small trimming job on the back corners of the coupler box has cured the problem. Regarding the tender - check your back to backs, but also check that the curve radius isn't too tight for the fixed wheeelbase of the tender, which will prevent it from taking the curve properly. A possible cure might be to remove the flanges on the centre set of wheels - if there is no other way of solving it - I know that some fixed wheelbase 0-6-0 and 0-8-0 locos also have this problem and will only work happily on larger radius curves

Thanks -- I'll check the bogies then of these coaches to see if they have enough clearance or if they're catching on anything. With tight curves, this could easily happen. Rob

[Russ Bellinis]

Another thing that just occured to me is that the wires transferring power from the rails to the motor on the tender trucks may be interfering with the truck swing. They could be only interfering in one direction which would explain why it derails going one way, but not the other.