What are common causes of derailment?

yellow_cad

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Thanks for all the great ideas. Most of my cars are 40' and I do have 2 foot radius turns, but these are not always where the problems occurs. The cars are Bachmann Big Haulers made from kits.
I have not checked all of the back to backs, but I surely will.
Sorry, but I still do not totally grasp the equalizing of the trucks. My trucks have the bearing housings on each side connected with a screw to the base plate that connects to the car with a pivot screw. Should I play with theses screws that attach the bearing housings to get more flexing such as a 1/4 turn and then try?
Thanks for the weight formula. I will bring the problematic cars up to weight, but I do seem to have a coupling problem that stems from too much pulling weight as it usually occurs on the second car in a consist of 7 or 8. I know about couplers in other gauges, but not in G scale.
Obviously, if a problem occurs in the same spot with different cars, then the track is the first suspect. I have a homemade track gauge and some clip ons, but would certainly invest in the aristocraft g scale track level/guage. Doing a search, any time I find one, they are out of stock. Does anyone know where one is available?
Thanks again for all of the assistance. Jim
 

Rhinochugger

Retired Oik
27 Oct 2009
29,241
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North West Norfolk
Sorry, but I still do not totally grasp the equalizing of the trucks. My trucks have the bearing housings on each side connected with a screw to the base plate that connects to the car with a pivot screw. Should I play with theses screws that attach the bearing housings to get more flexing such as a 1/4 turn and then try?
Given the fairly short bogie wheelbase and the depth of Bachmann flange, I wouldn't worry about this. As you've said that your passenger cars run OK, I doubt this is a significant issue.

As Greg has said, a lot of ideas have been suggested, it's difficult to put them in an order of priority.

My suggestion is watch and wait weight :p:p
 
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Gavin Sowry

Garden Railroader and Raconteur
27 Oct 2009
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Hutt Valley, NZ
Thanks for all the great ideas. Most of my cars are 40' and I do have 2 foot radius turns, but these are not always where the problems occurs. The cars are Bachmann Big Haulers made from kits.
I have not checked all of the back to backs, but I surely will.
Sorry, but I still do not totally grasp the equalizing of the trucks. My trucks have the bearing housings on each side connected with a screw to the base plate that connects to the car with a pivot screw. Should I play with theses screws that attach the bearing housings to get more flexing such as a 1/4 turn and then try?
Thanks for the weight formula. I will bring the problematic cars up to weight, but I do seem to have a coupling problem that stems from too much pulling weight as it usually occurs on the second car in a consist of 7 or 8. I know about couplers in other gauges, but not in G scale.
Obviously, if a problem occurs in the same spot with different cars, then the track is the first suspect. I have a homemade track gauge and some clip ons, but would certainly invest in the aristocraft g scale track level/guage. Doing a search, any time I find one, they are out of stock. Does anyone know where one is available?
Thanks again for all of the assistance. Jim

OK, second car in a consist of 8, on R1 curves. Firstly, congratulations on getting something that will haul that. The problem is definitely the weight of the cars (or more like, he lack of). It's what we call the stringline effect, all that weight at the back is trying to keep the train in a straight line, thus pulling off the light car on the curve, towards the front of the train.
 
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yellow_cad

Registered
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The back to back on my metal wheels falls between 39.6mm and 39.8mm.
 

korm kormsen

Registered
24 Oct 2009
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... Most of my cars are 40' and I do have 2 foot radius turns, but these are not always where the problems occurs. ...
i had this derailing problem with light newqida flatcars. (they have bogie mounted couplers)
when coming out of a R1 curve, the first two axles of the second car derailed.
the problem was, when the first flatcar was completely on the straight its coupler pointed straight back, while the coupler from the second car was still aligned with the sharp curve. the second's car's coupler was drawn to the straight, forcing the posterior axle of the bogie over the outside rail.
fixes, that worked for me.
1) a pound bag of leadshot on each car
2) giving the second car a frontcoupler, with sideways play against the bogie
3) glueing in a guardrail at the end of the curve as shown in the pic
4) using R2 or R3 curves as transitions between R1 curves and straights.

spurschiene05.JPG
Sorry, but I still do not totally grasp the equalizing of the trucks. My trucks have the bearing housings on each side connected with a screw to the base plate that connects to the car with a pivot screw. Should I play with theses screws that attach the bearing housings to get more flexing such as a 1/4 turn and then try?...
yes, just that. one side can be fixed, but the other side should allow the axles to alternately go up or down about three mm.
 

yellow_cad

Registered
1 Jul 2020
41
4
70
California
The weight of a typical car of mine is 24 oz. I weighed a car with plastic wheels. Now, Greg are you saying: 24 divided by 22.5 cubed. This is 24 divided by 11390.625 equals .002107. So, what am I missing here. Thanks, Jim
 

yellow_cad

Registered
1 Jul 2020
41
4
70
California
i had this derailing problem with light newqida flatcars. (they have bogie mounted couplers)
when coming out of a R1 curve, the first two axles of the second car derailed.
the problem was, when the first flatcar was completely on the straight its coupler pointed straight back, while the coupler from the second car was still aligned with the sharp curve. the second's car's coupler was drawn to the straight, forcing the posterior axle of the bogie over the outside rail.
fixes, that worked for me.
1) a pound bag of leadshot on each car
2) giving the second car a frontcoupler, with sideways play against the bogie
3) glueing in a guardrail at the end of the curve as shown in the pic
4) using R2 or R3 curves as transitions between R1 curves and straights.

View attachment 277582

yes, just that. one side can be fixed, but the other side should allow the axles to alternately go up or down about three mm.
The guardrail idea is very interesting, but I'm not sure I understand why it is near the inside rail of the curve rather than the outside rail. What physical role does the guardrail play?
 

Greg Elmassian

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8 Mar 2014
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you might re-read what I put:

the unladen weight of a REAL car... find the weight of a typical 40' box car on google, the unladen weight.

start in pounds (so you may have to convert tons to pounds).

Then divide that big number by 22.5 cubed.

a good approximation is 24 tons, or 48,000 pounds... (google is your friend)

48k / 22.5**3 is 4.21 pounds...

Greg

p.s. the guard rail controls the back side of the wheel, just like the guard rails on the outer rails of a switch, and the guard rails near the frog. Think of the way the wheel is trying to go straight.
 

korm kormsen

Registered
24 Oct 2009
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263
The guardrail idea is very interesting, but I'm not sure I understand why it is near the inside rail of the curve rather than the outside rail. What physical role does the guardrail play?
after observing the derailment situation for more than a dozen times, i was pretty sure, that the first car, by drawing the coupler of the second car to the straight line - did not draw the first axle over the inner rail of the curve, but the second axle over the outer rail.
so my first try was to hinder the second axle from doing that, was a guardrail on the inner side of the curve to keep the inner wheel of the second axle from leaving the inner rail. and it worked.

edit:
just looked at the spot and noticed, that after taking the above pic i did file the foot of the guardrail, that it could be nearer the normal rail.
the deed and the pic of it were totally forgotten.

guardrails01.JPG
 
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Fezwig

Registered
5 Jul 2016
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Croft, Warrington
Hi Yellow card,

Having read your post
Thanks for all the great ideas. Most of my cars are 40' and I do have 2 foot radius turns, but these are not always where the problems occurs. The cars are Bachmann Big Haulers made from kits.
I have not checked all of the back to backs, but I surely will.
Sorry, but I still do not totally grasp the equalizing of the trucks. My trucks have the bearing housings on each side connected with a screw to the base plate that connects to the car with a pivot screw. Should I play with theses screws that attach the bearing housings to get more flexing such as a 1/4 turn and then try?
Thanks for the weight formula. I will bring the problematic cars up to weight, but I do seem to have a coupling problem that stems from too much pulling weight as it usually occurs on the second car in a consist of 7 or 8. I know about couplers in other gauges, but not in G scale.
Obviously, if a problem occurs in the same spot with different cars, then the track is the first suspect. I have a homemade track gauge and some clip ons, but would certainly invest in the aristocraft g scale track level/guage. Doing a search, any time I find one, they are out of stock. Does anyone know where one is available?
Thanks again for all of the assistance. Jim
Keeping thing simple, I would firstly see if it was the same spot where you had a derailment and then see if it was the same wagon, ie if the second wagon derails then remove it and put on the rear of the consist, if the second wagon derails again but the wagon you placed at the rear stays on then you can now see it's not a fault with that wagon but either a track fault or too many wagons in the consist.
next I would reduce the number of wagons one at a time to see if that stops the derailments, if it does, then I would say your wagons are a bit light in weight, weigh a passenger car ( as you have no problem with theses) and a wagon and compare the weight, if the wagons are significantly lighter then slowly add a bit of weight to each wagon and see if the problem goes away.

with regard to the equalizing bogie heres a few photos
DSC_0050.JPG
the screw ( with the large head that looks like a washer) attaching the top side frame is loose and allows the bogie side frame (and wheels) to move up and down to deal with uneven track

DSC_0051.JPG
bogie on flat track
DSC_0052.JPG
so you can see the rear wheel has been raised and as that side frame can move up and down to compensate for the uneven track, in this case a bit of plastic and all wheels remain in contact with the rails

Hope this helps
 

Greg Elmassian

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Someone mentioned priorities for all these suggestions.

Here is my suggestion:

First bring all components into specification, i.e. correct any out of specification items
Next bring "your" specifications to bear, in my case it was couplers, coupler height, car weight
Next detect and correct the remaining issues (derailments, etc).


For a newcomer this goes opposite to what you are thinking (just fix THIS problem), and the urge to find the "silver bullet" that fixes everything.

I watched a newcomer run a train and the last car derailed... he just figured it was that car, and took it off. He ran the train and again the (new) last car derailed.... remove that car... rinse and repeat.. bottom line he found SEVEN bad cars.... hmm... wait after all that he figured there was nothing wrong with the cars, it was always the last car in the train!!! (by the way, the newcomer was me!!)


Bring into specification:
  • gauge all wheels (get a gauge or better still cheap digital calipers)
  • check all wheels for runout/wobbling.... replace as necessary
  • check all axle tips are lubricated, and the wheels spin easily
  • roll the car on the track and see if it still rolls along for a while (you can pass the previous test and fail this one)
  • check for correct coupler operation (couple uncouple)
  • check for correct coupler height
  • make sure couplers can swing side to side (going through curves) and not hang/lock up/return to center
  • check gauge of track in places where you have bent track, and check a few places in curves
  • check gauge of track through switches, inspect flangeways
  • look for sharp changes in grade of track, and the "cross level"

Add your specifications:
  • in your case, the cars supplied in Bug Mauler sets are WAY too light, you need to bring them closer to prototype unladen weight
  • replace plastic wheels with metal wheels

If you do all this, magically your layout and trains will run much better.


There is no single "magic bullet", and looking for one will normally take longer than doing all the above, and bonus, doing it right and systematically will be less frustrating.

Greg
 

yellow_cad

Registered
1 Jul 2020
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4
70
California
Thanks again for this wealth of information. I'm sure it will shorten my learning curve.
As to the back to back measurement. It was given as 40.5 mm. With a dial indicator I am getting 39.6 to 39.8 mm on my metal wheels. What is the acceptable tolerance on the 40.5 measurement?
 

Rhinochugger

Retired Oik
27 Oct 2009
29,241
3,508
North West Norfolk
Thanks again for this wealth of information. I'm sure it will shorten my learning curve.
As to the back to back measurement. It was given as 40.5 mm. With a dial indicator I am getting 39.6 to 39.8 mm on my metal wheels. What is the acceptable tolerance on the 40.5 measurement?
Slightly under won't give you a problem on plain track.

Just run your wheels through one of your turnouts to check that the wheels don't ride up on the check rails - if they run through OK, then you don't have a problem. My suspicion is that you'll be OK.
 

Greg Elmassian

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yellow (please let us know your real name)

please set your back to 1.575" for the USA... short story.

You want a longer story, please assimilate:

I have done a lot of research, and my recommendation comes from the NMRA standards.

Greg
 

yellow_cad

Registered
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California
yellow (please let us know your real name)

please set your back to 1.575" for the USA... short story.

You want a longer story, please assimilate:

I have done a lot of research, and my recommendation comes from the NMRA standards.

Greg
Greg, I have signed most of my posts Jim and Hearn is my last name. I have a 1954 yellow Cadillac Cd'V that I have had for a couple of decades so when I first went on discussion boards for old cars, Brit M/C, RC, N scale and now G scale I have always used the same handle primarily because it is easy to remember.

My back to back is from 1.560 to 1.570 (I had converted to metric only because the 40.5 was given to me in metric). The passenger cars that I have no problem with are in that range. Is there any way to alter the back to back measurement?
 

Greg Elmassian

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Thanks Jim! I only looked for your name on the posts on this page!

Cool on the car, I had a '54 Buick for a long time, weighed several tons, those were the days. Clearly not as cool as a Cadillac, but 8 people in it was no sweat!

You alter the back to back with a press or a modified C clamp.


you can try twisting, sometimes the wheel comes off the insulator... crazy glue will hold it in place.

Undergauge does not usually cause problems except on switches, but stock switches can also be improved.

I'm pretty sure your basic problem is weight of the cars, but if you work everything over, many issues will disappear.

Greg
 

phils2um

Phil S
11 Sep 2015
783
350
Ann Arbor, Michigan
Hi Jim,

my recommendation comes from the NMRA standards.
Here's the NMRA standard for large scale wheels:
Page 1 has the legend, page 2 the specs.

Greg, I have signed most of my posts Jim

If you go to "Signature" in your account details you can have your name and whatever else you may like appended to all your posts. Just keep it civil so's not to offend the Mods!;)

Edited to fix the NMRA link!
 
Last edited:

Fred2179G

Registered
20 Apr 2017
549
132
USA
Sorry, but I still do not totally grasp the equalizing of the trucks. My trucks have the bearing housings on each side connected with a screw to the base plate that connects to the car with a pivot screw. Should I play with theses screws that attach the bearing housings to get more flexing such as a 1/4 turn and then try?
In my experience, the Bachmann plastic trucks are made of fairly soft plastic and if you grab them in both hands by the axle ends (bearing housings) and twist, you'll find they have some ability to move.

That being said, on the track it won't happen if the car is too light. A heavy car will force the trucks to gtwist as needed on uneven track. I definitely concur with the general opinion that you need to add weight. Underneath between the trucks is best, but on the floor works too.
 

Greg Elmassian

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Phil, please do NOT recommend that standard!

That is the "toy train" standard, it is a joke if you really have studied the issues... it is there to "grandfather" in toy trains.

I do, on my page listed, go through the reasoning of which standard to follow, there are indeed THREE standards for "G" scale.

I would ask you to read my page and see after reading you agree with my logic and assessment.

Greg
 

Rhinochugger

Retired Oik
27 Oct 2009
29,241
3,508
North West Norfolk
OK, just done a conversion of 1.575", and it's much nearer 40.1 mm. Now that again is much closer to Jim's back-to-back measurements.

So, for my two pennyworth:

  • I don't think the back-to-back is an issue
  • I don't think the lack of compensation is an issue

So we're at:

  • Weight
  • The possibility of 'stringing' or coupling related issues on tight curves.

Back to Greg's suggestion - add some weight, then see what happens.