G Scale Model Train Forum banner
1 - 6 of 6 Posts

· Premium Member
Joined
·
1,845 Posts
Discussion Starter · #1 ·
I have a problem with a turnout causing some cars to derail. After investigating I can see the reason. As the cars approach the turnout they are coming out of a 9' diameter curve. The turnout is a left hand #6 and cars are coming at it head on.

When the points are thrown for the divergent path, what I see is that since the cars are coming out of a curve the wheel flanges are pushed all the way to the rail where the point is touching the stock rail. The wheels hit the very end of the point and bounce up, causing some to derail. This occurs even though the points are recessed slightly in the rail. These are sunset valley switches. I see now I should not have a curve immediately before a switch, but to modify the layout now is more time that I have.

So I was considering a couple of options and wondering if anyone could say one of these is better or another solution that might work:

1 - grind down the end of the point to be even thinner than it is.
2 - grind down the rail so the point fits inside it further.
3 - add a piece of thin brass just before the point to help guide the wheels around the point.

I see a problem with each of these:
- The first, I may grind the end of the point down too far and cause a problem?
- The second, with the rail ground down, the point will sit inside it better, but now when I throw the point for the straight path it may not go over far enough without modifying the points to be further spread apart?
- The third, not sure if this will work or just push the problem back to just before the point?
 

· Premium Member
Joined
·
1,845 Posts
Discussion Starter · #5 ·
Dave,

1) Sunset Valley #6

2) Most cars coming out of the 9' diameter curve hit the end of the point and bounce up, some bounce enough to derail, even at low speed. It's generally the lighter cars, the heavy ones seem to be able to hit the point and stay on track.

3) Wheel gauge is correct, checked. I should have explained better, it's not the point of the frog but the point itself, the very end where it sits up against the stock rail. So it's the very beginning of the point, way before the guardrails.
 

· Premium Member
Joined
·
1,845 Posts
Discussion Starter · #9 ·
Doug, Greg and Paul, thanks for your input. I’ll try to answer your questions.

Yes I have a 9’ diameter curve that comes into the point rail end of the switch (so head on â€" not trailing â€" to the switch), but it is not a reverse curve â€" that is the curves go the same direction so it is not an S curve so to speak.

I'm using the metal AristoCraft tool for track gauge min/max and the wheel gauge min/max. It's the one that has the levels built in. The switch rails and wheels are in gauge according to that tool. I haven't had the time yet to try #1 above but that is what Sunset Valley said to try first also.

Yes the point rail slips under the stock rail a bit when in position to take the divergent path, but there is still a thin part of the point that sits next to the stock rail and if a wheel/flange is pushed all the way over the to that rail I can see and hear it slightly hit. The cars having issues are the AMS freight cars. Running the heavier AMS passenger cars through the switch didn’t reveal the issue. I did check the passenger cars after having issues with the lighter freight cars and saw they also can slightly hit the end of the point but continue through, I’m assuming because of their weight? The lighter freight cars derail consistently when a flange hits the very end of the point rail. Since the flanges on these cars are not very deep, more prototypical, and the cars are lighter, a slight lift of the flange is enough to push the flange over the rail and derail them.

I would have preferred a switch design so the points fit entirely into the rail (i.e. indented) then no chance for a wheel flange to pick the point. Sunset Valley sort of did this on the straight path side of the point rail. On that side I can see the stock rail is actually indented slightly making it virtually impossible for a wheel flange to hit the end of the point rail on that side.

The saga continues …

I didn’t have time to resolve the wheel flanges hitting the very tip of the point rail so I decided to run the train in the opposite direction. This way the switch points are now at the trailing end as the train comes through the switch. However, switching the train’s running direction now makes my other switch a problem. That switch has a long straight track before the switch so I don't have the issue of the wheel flange hitting the end of the point. However, on this switch, as the wheels come through on the divergent path of the switch I see the wheel flange hit the very tip of the frog. At first I figured the wheels or switch must be out of gauge, how else could the flange hit the frog point? Measured the wheels and found they are right on, although at the max in-gauge width. So then I measured the switch gauge, right on again. I can see now that the gap between the stock rail and guard rail furthest from the frog is the issue. The gap is too large and allows the opposite wheels to move too far into the frog.

The guard and stock rail across from the frog butt up against each other at their base, but this still allows for a significant gap between the tops of the rails where the wheels/flanges ride. I remembered Doug once said guard rails should be about 2 flange widths from the stock rail. Now I see how significant that is. A better design for the switch would be to reduce the base of the guard rail before butting it up again the stock rail. I assume the easiest remedy at this point is to do what Todd did above, which is add some brass strip or something to the side of the guard rail reducing the gap between it and the stock rail. This will keep the wheel flange closer to the stock rail and in turn keep the opposite wheel flange from hitting the tip/point of the frog.

I can see why some folks call switches a necessary evil :-( The thing is there are easy fixes for these issues, so I don’t understand why manufacturers don’t implement them?
 

· Premium Member
Joined
·
1,845 Posts
Discussion Starter · #12 ·
Doug, Yes, I believe the point can fully be recessed without too much trouble, that was my option #2 above. The problem is then the switch may not go far enough back the other way, so I could have problems on the straight path. Unless I modify the points to have a further spread, as my switch stand is set for a specific point travel length.

Paul, guess I just got lucky :-( Glad to hear all is well with yours.
 

· Premium Member
Joined
·
1,845 Posts
Discussion Starter · #15 ·
Thanks to all for their input. Finally got the issues resolved and the trains are running through the switches with no problems; not one derailment in 2 days of almost non-stop running :) I ended up filing down the very end of the point rail that sits next to the stock rail for the divergent path. Now the wheel flanges have almost nothing to hit :) The point on the straight path rail was already hidden well so no need to do anything there. Also, put in some extra brass strip on the guardrail next to the stock rail for both the straight and divergent paths, as posted in the picture above by Toddalin. This keeps the wheels close to the outside stock rail, thus ensuring the wheel flanges using the frog don't pick the point of the frog.
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top