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Author Topic: one way derail  (Read 7403 times)
mabloodhound


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« Reply #15 on: October 23, 2010, 08:36:25 PM »

I found this definition on another modeling site:
 "Guard Rail:   A longitudinal rail running alongside a railway track and raised in height above the running rails. Guard rails are sometimes found on bridges and are intended to restrain the lateral movement of vehicles which might become derailed."

And I found this: " I looked this up in the ATSF system standards vol 1. ATSF standard was 45' from point to bridge. I also found some other interesting stuff that you may also find interesting. Please enjoy this daily dose of useless information.

The General manager had the option of extending guard rails up to 300'

The points were # 10 frog points.

Guard rails are spaced 10" on center away from main rail. (I'm not sure how this compares to NMRA)

The guard rail begins to taper inward 1'-8" away from the bridge.

Using the same weight of rail for the track and the guard was acceptable. (good because I don't want to order more rail)

The front of the point is beveled at 45 degrees (relative to the horizon)

No tie plates are used beneath the guard rail.

 On double track mains that had dedicated directions of traffic (like a highway), points were only required on the leading end of the guard (before the bridge). The unpointed end of the guard rails (after the bridge) ended 10' after the bridge without any bends.... never heard of this before. I wonder if this ever existed outside the standards, "

from the MR forum http://cs.trains.com/trccs/forums/t/169494.aspx

I do like your though of using a guard rail as it is most prototypical.
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Dave Mason

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jward


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« Reply #16 on: October 23, 2010, 09:41:54 PM »

code 83 rail makes excellent guard rail. it's what i use, but then all my track is code 83. doing the entire bridge with guard rail would look good. usually bridges had guard rails on both rails. but some lines with extra sharp curves had guard rail on the inner rail of the curve whether it was on a bridge or not. the western maryland railway's lines out of elkins, wv to weebster springs, and to cumberland, md were good examples of this. the affected curves were usually restricted to 10 or 15 mph.

the atsf standards quoted mentioned that the guard rail was taller than the running rail. i've never seen that except in rare instances, such as a guard rail to keep wheel flanges away from swithpoints. most of the real ones i've seen, including the western maryland ones, were slightly lower than the running rails. for simplicity, i use the same size rail for everything.
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Jeffery S Ward Sr
Pittsburgh, PA
Keusink

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« Reply #17 on: October 24, 2010, 11:35:33 AM »

Gentlemen

Thank you all so much for your feedback. I think I know how to do it now.

Because this is a 4 year project (I have a professional life and twin 8 year old boys) I took on the most interesting set I could find. I only want to do this once. Combine long, curved, 2% grade to make a trestle bridges  together with DCC wiring and you have more than a challenge for a newbie.

I'm in Southern Oregon, 4.5 hours away from the nearest competent LHS. Nearest club is 3.5 hours away. Without you guys, this trainset would never be finished.

What a helpful group of real gentlemen.

(Be sure I'll bother you again).

Chris
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #18 on: October 25, 2010, 01:58:17 AM »

Tuning in late, but here is another thought for you.  Earlier, jward suggested there might be a twist in the track.    If you  have a curve on a grade, there is automatically a twist in the track if you insist on using a helical curve, that is, if you make both rails radially level with one another.  If the amount of twist results in more than about 1/2 of a flange being lifted off a rail head, there is a very good possibility of a derailment occurring.  Long wheel bases and unsprung drivers make it pretty easy for steam locomotive to derail on twists.  Diesels usually do not derail on a twisted track as long as both trucks rotate freely about the  roll and pitch axes.

If your GS-4 is having problems on flat 22" radius curves, then it will almost certainly have problems with the twist in 22" radius rising curves.  I assume you have checked both the track and the wheels with an NMRA track and wheel gauge adjusted things accordingly.  When checking, be sure the gauge is parallel to the axle or to the ties, which ever applies.  Otherwise the gauge will be narrower than you think it is.  If your track was hand laid, I would suggest spacing the curves a little wider apart than straight track to avoid pinching problems.  This is rather more difficult to do with flex track.  The alternative is to set the locomotive drivers slightly under gauge, which may get you around the bends but may give you problems with the turnouts.  In that case, a more radical solution is called for - removing the flanges from the drivers on the second and third axles, leaving flanges only on the end drivers.  Check your locomotive - this may already be the case.  Before doing anything so radical, I would suggest you check the side play of the driver axles after gauging the wheels.  Flanged drivers need more side play than unflanged ones.  Sometimes there is something restricting side play, such as flash on the wheel hubs, bent valve gear, or stuck power pickups.  Sometimes there is lint/hair wrapped around an axle preventing it from moving sideways.  Sometimes the side play is restricted for only part of a revolution of an axle.  This can be hard to see but shows up quickly if you power up the locomotive while it is upside down and gently move each axle back and forth repeatedly as the wheels are turning slowly.  Don't be surprised if some axles have no side play, but be suspicious if two axles next to each other both lack side play.

If all of this gets you GS-4 running on flat curves but not on the trestles, then have another close look at the trestles to see if you can make the curves non-helical.  If the curves are relatively short, they can be made non-helical, that is, they can be canted so that the tops of the rails lie in the same plane throughout the curve.  This moves the twist to the straight track next to the curve where is generally causes fewer problems.  However, if the straights are short, the twist may be more than enough to derail the locomotives even on straight track.

If none of this works, or if it is impossible to do on your layout, the last resort would be to spring the drivers, assuming they are not already sprung.  In its simplest form, the slots that the driver axle runs in are lengthened vertically, a hole is drilled in the frame above each end of the axle, and a small spring is dropped into the hole.  Now instead of the frame riding on the axle, it is riding on two springs which are riding on the axle.  Generally this type of work is best farmed out and most likely things will never come to this.

Bottom line:
(1) check the gauge of wheels and track
(2) check for side to side free play in the axles.
(3) check to see if the second axle is really lifting the first or whether the track itself is pushing the axle up (pinch.)
(4) check the frame for warp or bend.  Set the locomotive on a mirror (preferably a front silvered one) and check that all wheels touch the mirror.

If any of these test show a problem, correct the problem before continuing.  Lots of luck.

Jim   
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Keusink

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« Reply #19 on: October 25, 2010, 06:21:18 PM »

Thanks Jim Banner.

I think you have touched on the problem. The trestle bridge components are made from a well known kit provider When put together, I noticed the bridge crossties are not level. Instead of laying the track directly on the crossties, therefore, I caulked flextrack onto the bridge ties. I had hoped the caulking and flexties would even out any declivities.

I put on guardrails, inside curve. They have helped a good deal. Toothpicks under the inside tie edges also seem to help. Raising the inside of the curve with a finger seems to help. I think what is happening is a declevity is miniscule, but combined with the twist it raises the first driver off the rail. Because of the turn, it does not come back down in the right place, and the loco derails.

There is VERY little side to side play in the drivers. They are not following the diverging route on two of the Walthers DCC friendly turnouts, either. I do not know if the lack of driver play is unique to my loco, or whether it is typical of the Bachmann GS4.

Being a newbie, I do not know what you are referring to re: spring drivers?

I thought if there was an incline to the inside, the loco would be inclined to fall into the set. Outside is a loooooong drop to the concrete in what would probably be the longest (scale) locomotive fall in history. So originally there was a slight elevation to the outside rail. The problem seems to lessen when I try to level the rails. I suspect each rail has very hard to see bumps, but I do not know how to eliminate them. When you raise one place, it causes the rail to change shape further along the rail.

Gee. Now I can say I've talked with Jim Banner.
Thank you. I appreciate any more thoughts.

Chris
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #20 on: October 26, 2010, 01:26:45 AM »

When a locomotive has sprung drivers, it means the weight of the locomotive is transfered to the drivers via springs.  This helps insure that all the drivers are on the rails all the time, even if the rails have humps, bumps, twists and other problems that make the trains rock and roll.

And hey, now I can say that I have talked to Chris -  TWICE.

Jim
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glennk28

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« Reply #21 on: October 26, 2010, 12:34:47 PM »

Keep in mind--before asjusring the coupler pins--be certain that the coupler is mounted at the correct height.  gj
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jward


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« Reply #22 on: October 26, 2010, 07:56:06 PM »

.

I put on guardrails, inside curve. They have helped a good deal. Toothpicks under the inside tie edges also seem to help. Raising the inside of the curve with a finger seems to help. I think what is happening is a declevity is miniscule, but combined with the twist it raises the first driver off the rail. Because of the turn, it does not come back down in the right place, and the loco derails.


therein lies the problem. the driver SHOULDN'T lift off the rail. it really doesn't metter whether it comes back down on the rail or off the rail, if it lifts, you have a potential problem. i think you are on the right track trying to level your track. the toothpicks as wedges are accomplishing what i would have done with pieces of index card. my experience has been that it isn't where your track tilts toward the inside of the curve that's the problem, but where it tilts toward the outside, or where there is a twist. you are methodically trying to eliminate both on a temporary basis before deciding on a permanent fix. experimant, use logic and some common sense, and you'll find and fix the problem.

btw, jim is one of the best resources we have here. i think he's been in the hobby longer than i've been alive... Grin
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Jeffery S Ward Sr
Pittsburgh, PA
Doneldon

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« Reply #23 on: October 27, 2010, 09:05:37 PM »

Chris-

Look at it this way: When you curve your track you are changing the direction of the track in one dimension.  If you add an elevation change as well you are introducing a direction change in a second dimension.  If your track is not level side to side, even if intentionally such as with a superelevated curve, you are changing direction in all three dimensions.  It's no wonder there are tracking problems.  The solution is to manage these changes and, insofar as is possible, change only one dimension at a time.  For example, start the grade a little before you start the curve.  Get into the curve before you start the twist (superelevation).  You can visualize these three dimensions as lines through a locomotive on your track.  The curve represents rotation around the vertical line running up and down through the center of the loco.  The grade change represents rotation around the line running horizontally from side to side.  The superelevation represents rotation around the horizontal line running from front to back of your loco.
                                                                                                                            -- D
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Keusink

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« Reply #24 on: November 01, 2010, 03:52:11 PM »

Thank you all. There are so many permutations of twists that I would at least level the trestle bridges and leave the curves and grade for the l girders were I ever to do it again. I'll keep working at it; doesn't look like I have a choice.

You've all been most helpful.

Chris
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BradKT

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« Reply #25 on: November 14, 2010, 02:49:40 AM »

Have you considered the possibility that you simply have a defective piece of track?  Maybe it wasn't originally defective, but you may have slightly twisted it so the rails are not the exact same height.  Try replacing it and see if you have this same problem before you do all of this other stuff that has been suggested.  If you have the same problem a second time, at least you have eliminated this issue, but it really sounds to me that this might be a real possibility as soon as I read that you were using flex-track at this location.

The problem could be in one of two locations...either where the wheels on the front truck derail or the location where the REAR wheels are located when the derailment happens.  These engines weigh enough to keep both trucks on the track and if the front truck is slipping off, the problem could easily be where the rear wheels are located when the derailment happens because it raises that front truck slightly...just enough to derail when you are going one way, but not the other way.  We are talking about an incline here.  It could be just a rise or a dip...that's all it takes.

This really sounds like a track issue to me.  When it comes to derailments, HO scale trains are really unforgiving (the engines and cars all have a straight, inflexible chassis and do not have independent front and rear suspensions) and the track has to be installed just right the first time or you are going to have to do it over...eventually.  Get it right the first time or you will have to do it over after endless frustration.  Trust me on that!  I know.
« Last Edit: November 14, 2010, 03:13:34 AM by BradKT » Logged
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