Baffling derailment

[Dave-the-Train]

I blame these variable problems on Gremlins... those pesky beasts that hide until you have visitors you want to impress...

[jecorbett]

My 2 cents worth here is that if that plastic cover was low enough to catch the spreader bar on the switch points it wouldn't go through any turnouts or cross overs as it would snag the rails also. That cover may be loose enough to produce what Jeffrey stated though or the truck is not swiveling freely as was stated also. Ken

That makes sense. Now that I think about it, I don't think the throwbar is what was catching the bottom of the truck. The problem truck was the one under the cab but it was the other truck that was over the throwbar when I began to feel the binding when I pushed the engine through the turnout. The trailing truck was over the crossing rail at that point and I'll bet that is what it was dragging against. It would also make sense that the angle of this rail would throw the truck to the left which is the side it derailed on every time. I wish I was confident that I had solved the problem but the fact that I couldn't feel anything that seemed to pop back into place when I pressed on this bottom plate leads me to believe it might start to sag again. I'll have to monitor it but at least now I'll know what the root cause is.  

[Eriediamond]

My 2 cents worth here is that if that plastic cover was low enough to catch the spreader bar on the switch points it wouldn't go through any turnouts or cross overs as it would snag the rails also. That cover may be loose enough to produce what Jeffrey stated though or the truck is not swiveling freely as was stated also. Ken

[selector]

That's a good bet, Jeffrey.  It would make perfect sense.

[jeffrey-wimberly]

I had a similar problem with a P2K E7. It would go forward through a turnout just fine, but reverse and back it through the turnout, whoa Nelly! The middle wheelset of the front truck would lift and that would be all she wrote. I examined the truck, checked the gauge of the wheels, made sure the wheels rose and fell slightly as they're supposed to, everything checked out. I tried it again and it derailed again while backing through the turnout, as it did before. This time I took the truck apart and examined everything. While looking at the wheelsets I noticed that the drive gear on the axle of the middle wheelset didn't appear to be properly centered. Upon closer inspection I found that the wheels were indeed off center. This was forcing one wheel hard against the rail. It explained the derailments and why it happened only when the loco was backing through the turnout. The wheel, in being pressed against the rail, would catch on the point rail and the flange would ride up and over the top. I disassembled the wheelset then reassembled it in the proper configuration then reassemble the truck. When I tried the loco out again it went through the turnout forward and backward perfectly. It only took me three hours to find the problem.

[Brian In Arkansas]

Sounds like a design flaw on Atherns part...

Could it be glued on permanently or removed entirely?

Just thinkin...

Brian

[bogp40]

I began having a derailment at a specific turnout with one of my Athearn RS3s. The curved section of this #8 turnout begins a broad curve and the derailment was occuring near the points of the turnout when the engine was entering the curve. There were several curious things about this. I have 3 of these Athearns but only one had the problem and only when running long hood forward. The front wheel of the truck on he short hood end would jump the track and pivot to the inside of the curve almost every time. I normal run my RS3s short hood forward but this could be a problem if I wanted to MU so I decided to look into it. The most obvious thing was the wheels might be out of gauge but the NMRA gauge said no. I also checked the track which also was in gauge which I expected since only one of the engines was having the problem. When I pushed the engine slowly through the turnout, I could feel something binding as it got to the points and I needed to apply added pressure to keep the engine going forward. I turned the engine over and could see nothing out of the ordinary and compared it to one of the other RS3. Everything looked the same until I noticed the plastic cover on the bottom of the truck that holds the axles in place showed signs of wear at both ends of the truck. It appeared to be in place but I pressed it firmly to the truck and ran it over the curve and suddenly it went smoothly throught the turnout. Then when I reversed the engine so I could run it back through the problem area, it derailed about a foot from the turnout, this time jumping the track to the outside of the curve. I once again pressed the bottom cover back over the truck and this time, it was able to go back and forth about a half dozen times with no derailment. Looking closely at the turnout, I noticed there also seemed to be some wear on the plastic plates that hold the point rails to the throwbar. They seemed to sit a little high and apparently the combination of these high plates and the low cover was enough to cause enough friction to derail the loco. I find it a little surprising that apparently the clearance on these trucks is so tight that even slight sagging of the cover plate that wasn't apparent to the naked eye was enough to cause a problem. Also, when I pressed this cover on against the truck, I didn't feel anything that seemed to snap back into place. This leads me to wonder if this part will sag again and continue to be a problem.

I am curious if others have had a similar problem with the Athearn RS3s or any other loco. Can I expect this to continue to be a problem not just with this loco but all my RS3s. 

It doesn't sound like a track problem seeing as this is the only piece that derails and only that one particular truck (long hood). You've check the gauge, but say that when slid through seems to snag. The truck may not have smooth movement to turn to follow the point rail, thus the picking. It may be hard to tell how the trucks move unless the full weight of the loco is resting on the frame. Lay the engine on a smooth surface, glass the best and see if the truck turns freely.

In addition to how well the truck can swivel, check that it is not too tight and has some sideways play. This allows for the wheels to stay in contact with no lifting however slight, if there is any irregularity in the level of the track.

I had problems w/ first run P2K SD7s doing the same.

[selector]

My layout and equipment rarely functions the same way day-to-day, let alone week-to-week.  I have run my Challenger past a steep and low clearance embankment, found that the cab edge scraped the dried goop at its level and threatened to derail the loco.  No probs, just file away some of the goop, vacuum, and try again.  Worked nicely, and all is well.  Next day, back the loco past the same spot, and it tilts.  Grrr. File, file, file, vacuum, and try again.  That did it.  Two weeks later, same thing.  It is like the material creeps or sags under its own weight over time.  Locos become noisy that were silent, and noisy ones get more silent.  My FA2 was having problems with shorting for no apparent reason, until I watched it closely and found the decoupling wire that dangles from the coupler was scraping the rails and turning sideways to cause the bridge.  Why now and not last week, last month, and all the other times I have run this loco?

Life in the hobby's tough; then you die. 

[jecorbett]

I began having a derailment at a specific turnout with one of my Athearn RS3s. The curved section of this #8 turnout begins a broad curve and the derailment was occuring near the points of the turnout when the engine was entering the curve. There were several curious things about this. I have 3 of these Athearns but only one had the problem and only when running long hood forward. The front wheel of the truck on he short hood end would jump the track and pivot to the inside of the curve almost every time. I normal run my RS3s short hood forward but this could be a problem if I wanted to MU so I decided to look into it. The most obvious thing was the wheels might be out of gauge but the NMRA gauge said no. I also checked the track which also was in gauge which I expected since only one of the engines was having the problem. When I pushed the engine slowly through the turnout, I could feel something binding as it got to the points and I needed to apply added pressure to keep the engine going forward. I turned the engine over and could see nothing out of the ordinary and compared it to one of the other RS3. Everything looked the same until I noticed the plastic cover on the bottom of the truck that holds the axles in place showed signs of wear at both ends of the truck. It appeared to be in place but I pressed it firmly to the truck and ran it over the curve and suddenly it went smoothly throught the turnout. Then when I reversed the engine so I could run it back through the problem area, it derailed about a foot from the turnout, this time jumping the track to the outside of the curve. I once again pressed the bottom cover back over the truck and this time, it was able to go back and forth about a half dozen times with no derailment. Looking closely at the turnout, I noticed there also seemed to be some wear on the plastic plates that hold the point rails to the throwbar. They seemed to sit a little high and apparently the combination of these high plates and the low cover was enough to cause enough friction to derail the loco. I find it a little surprising that apparently the clearance on these trucks is so tight that even slight sagging of the cover plate that wasn't apparent to the naked eye was enough to cause a problem. Also, when I pressed this cover on against the truck, I didn't feel anything that seemed to snap back into place. This leads me to wonder if this part will sag again and continue to be a problem.

I am curious if others have had a similar problem with the Athearn RS3s or any other loco. Can I expect this to continue to be a problem not just with this loco but all my RS3s.