# Car lenth/locomotive lenth/ derail?



## Don Trinko (Oct 23, 2012)

I'm starting to notice some peculiarities. I have 2 loops, both o27 curves. The outer loop has a 5" strait between the curves at the end's of the loop. the inner has 4 o27 curves on each end.
1 peculiarity is that my passenger cars will pull the front truck off if i hook up a caboose on the inner loop but it works fine on the outer loop.
Another peculiarity is that my 0-6-0 switcher and a short diesel switcher will pull the trucks on the 1st car off the track ,unless I add a lot of weight, on the inner loop but works fine on the outer loop without having to add weight.
I have an 0-8-0 Locomotive , several 4-6-2's with tenders and a long dual motor diesel that work fine on either loop.
Again; all the turn track is o27. Any rule of thumb? I'm guessing that if I had a bigger layout with o31 minimum these peculiarities would disappear.
Thanks; Don


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## gunrunnerjohn (Nov 10, 2010)

First off, I'd weight the cars according to the NMRA standards, 5 oz plus 1 oz for each inch of body length. I find that cures a lot of ills. If you have heavy cars, run them in front of the consist.

The pilot travel will sometimes pull the cars off as well, do you have free travel of the pilot of the problem locomotive? Do the couplers have any significant resistance to moving the full travel?

Weighting and proper pilot travel should fix much of the issue.

One piece of advice regarding O31 "upgrades". If you plan on going to full O-gauge, consider skipping O31 and going for a larger diameter. I have a ton of O-31 track that I accumulated in preparation to do my layout, after running on the club layout with O-72, I'm rethinking my plans and accumulating O-72 curves.


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## Don Trinko (Oct 23, 2012)

Thanks; I will start with the car weight. The coupler on theproblem loco moves freely but the end of the loco moves out a lot on turns. I think the distance between the last wheel on the loco and the 1st wheel on the car is longer than the same distance from the tender/car. Don


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## gunrunnerjohn (Nov 10, 2010)

The key element here is can the coupler follow the curve and be centered for the following car to be pulled right down the track and not to the side. Even if that's the case, weight makes a big difference.

I've found that with long trains, putting a couple of really heavy cars in front helps, I have a couple of diecast hoppers, they're pretty hefty.


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## Don Trinko (Oct 23, 2012)

I just found the problem with the 2 short switchers. unfortunately not the solution. the coupler does not move side to side enough. The loco coupler is maxed out to the side and pulls the front truck of the following car off the track. It does this early in the turn on the 1st curve track. I would have to modify the coupler some how so it moves further to the side on the loco or the car. I think the tender takes care of this when used with the other loco's because of the way they mount the rear coupler.
when i added a lot of weight to the 1st car it pulled the loco off the track.
The turns on my outer loop look the same when i compare them. I compares them side by side and did not see any difference. I suppose it is possible that i can't tell o27 from o31. Don


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## gunrunnerjohn (Nov 10, 2010)

Although it's contra intuitive, many small switchers seem to require larger curves. I had a little 0-6-0 that had problems on O-31 curves, but worked with Fastrack O-36 curves.

What's the specific model of the problem locomotive? Have you looked at it's stated minimum curve specification?


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## Don Trinko (Oct 23, 2012)

One is a lionel dockside switcher. The other is a RMT 4371. It says "compatible with all o or o27" on the box .
got my dial calipers and a straight edge out, The outer loop is o31 or larger. Not sure how to get an exact measurement.
but it is a larger radius than o27. Don


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## Big Ed (Jun 16, 2009)

If you go with larger curves and you don't have the room, for the O/27 setup an O/54 (O/27 size) would work too.
They don't make an O/72 in the O/27 tube track, the largest for it would be O/54.

Do you have a mix of O/27 and O track? You know they are different right?

We have a thread about an RMT doing just what you said and how someone fixed it, I will see if I can find it.


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## Big Ed (Jun 16, 2009)

Nope his modification was for an RMT beef and the problem was different.

Here it is if you want to take a look,

http://www.modeltrainforum.com/showthread.php?t=12946


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## Don Trinko (Oct 23, 2012)

Yes, all my track is o27 type.I am aware of the difference. Don.


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## Big Ed (Jun 16, 2009)

Don Trinko said:


> Yes, all my track is o27 type.I am aware of the difference. Don.



I thought O/31 is the O sized taller track?

They make an O/31 for the O/27 track? 

I didn't know that I thought it was O/27 then O/42 and then O/54? That was the only thing you could get for O/27 height?
Any thing else was the taller O gauge track. I know they don't make O/72 in the O/27 height.


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## Big Ed (Jun 16, 2009)

OK If your running O/31 curves then that IS O track not O/27?
This is where you are confusing me saying you might be running O/27 curves mixed with O/31 curves.....they are 2 different height rail sizes?

The 2 track don't mate because of the pin size and the height of the track.
You can fabricate up some pins and shim the O/27 track to the O size rail.

O/27 is the smallest curve in the O/27 track which is 7/16" high.
O/31 is the smallest curve for O gauge track which is 11/16" high.


a copy and paste,
tinplate track in O-27 profile is a very popular choice for smaller O-gauge layouts. The O27 series track dates from 1930s. The principal difference between the O27 and the regular O track is the diameter of the smallest curve: nominally 27 inches for O27 and 31 inches for regular O (in reality about 30 inches across the outside rails).


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## gunrunnerjohn (Nov 10, 2010)

Sometimes the manual and reality clash. I take the case of the Lionel Two Truck Shay. It specifies O36 minimum curve, but it'll pull the cars off the curves unless you use at least O42. Lionel knows about it and just says... tough!


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## Don Trinko (Oct 23, 2012)

All my track is the o27. The height from the base is all the same and not "O" gauge height.
It appears that I made the inner loop tighter and that is why I am having some problems with certain loco/car combinations. I just measured and it is 25" from outer rail to outer rail. I did not know it was that tight but I made it tight so I could have 2 loops and clearance for trains going opposite directions.
Most of my trains work fine on the inner loop including some long passenger cars.
My outer loop started with a "Whirlpool" set that they ordered direct from Lionel. this is all on a 38" x 8' layout. I made it 38" so It could hinge down when not used. Don


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## Big Ed (Jun 16, 2009)

How did you make a 25" circle out of track that is supposed to measure into a 27" circle? 

Did you actually hand bend the rail to make it fit? 
If so that would be your problem as 27" would be the minimum to run the trains on. Even with 27" some of the larger stuff would either look funny or not negotiate the curve.


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## gunrunnerjohn (Nov 10, 2010)

I suspect he just didn't get the joints exactly 100% seated, you can do that with tubular track. Looks a bit funny, but sort of works.


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## Don Trinko (Oct 23, 2012)

I tried to get all the joints tight but in my zest to make 2 loops I got carried away with making a tight turn! Amazingly most of my trains work fine on the inner loop
It does explain why the couplers on the two short loco's are maxed out in the turn.
Thanks for all the help. I am at the stage of this where "a little knowledge is a dangerous thing" Don


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## gunrunnerjohn (Nov 10, 2010)

Every journey starts with a single step.


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