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Couplers and buffers cause derailment
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Offline PeFu  
#1 Posted : 14 February 2021 07:15:11(UTC)
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PeFu

Sweden   
Joined: 30/08/2002(UTC)
Posts: 1,210
I have just started to test my two new Märklin 43574 "Zürich S-Bahn" Bi-Level car sets. I was surprised, the cars sometimes derail at some curves on the layout. Googling, I found that this is a pretty common feature for ”newer” cars with close couplers, that the upper part of the couplers is too high and could stick to the buffer at curves. Note that I have no derailment problem running other trains on the layout.

I sent a note to Märklin, and they responded me to send the cars to Göppingen for review. However, before (and maybe instead of) doing this, as I will replace the couplers to current conducting types, I wonder:

Confused Would there be a specific type of current conducting couplers that could eliminate the derailment of the cars?

I’m looking at e.g. the ”fixed” Märklin 7319 which seems to have a lower profile, than my current couplers installed on the below pic:

0F2BD904-F678-4EC9-B0D6-FDC3C551CA09.jpeg
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Offline river6109  
#2 Posted : 14 February 2021 09:36:55(UTC)
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river6109

Australia   
Joined: 22/01/2009(UTC)
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Location: On 1965 Märklin Boulevard just around from Roco Square
I've replaced "all" Märklin couplers with Roco latest ones, got rid of Fleischmann and Roco's earlier design, you just have to be truthful what works and what doesn't

John
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Offline kiwiAlan  
#3 Posted : 14 February 2021 13:17:59(UTC)
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kiwiAlan

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Joined: 23/07/2014(UTC)
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Location: ENGLAND, Didcot
Originally Posted by: PeFu Go to Quoted Post

0F2BD904-F678-4EC9-B0D6-FDC3C551CA09.jpeg


To me that looks like the buffers on the left hand coach are slightly lower than the right hand one, and look like they could interfere with the coupling.
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Offline rhfil  
#4 Posted : 14 February 2021 13:56:47(UTC)
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rhfil

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Joined: 05/09/2014(UTC)
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Location: NEW HAMPSHIRE, Somersworth
If you look at the doors and the roofs it appears that the entire left hand car is lower. I would check to see if the trucks are correct. I had a problem with long coaches derailing when going around corners. I noticed that the trailing coach wheels would be raised off the rails and then drop down off the rails. Finally resolved the problem by working the trucks to loosen them up. Apparently they were too stiff.
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Offline river6109  
#5 Posted : 14 February 2021 15:43:42(UTC)
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river6109

Australia   
Joined: 22/01/2009(UTC)
Posts: 14,726
Location: On 1965 Märklin Boulevard just around from Roco Square
Originally Posted by: kiwiAlan Go to Quoted Post
Originally Posted by: PeFu Go to Quoted Post

0F2BD904-F678-4EC9-B0D6-FDC3C551CA09.jpeg


To me that looks like the buffers on the left hand coach are slightly lower than the right hand one, and look like they could interfere with the coupling.



In this case you may have to add a thin washer between the bogie and the frame so they have the same heigth
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Offline rhfil  
#6 Posted : 14 February 2021 17:17:06(UTC)
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rhfil

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Joined: 05/09/2014(UTC)
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Location: NEW HAMPSHIRE, Somersworth
If you look very closely at the NEM sockets they appear to be even but the gap between the top of the sockets and the bottom of the carriages is different. Something is causing the right carriage to be higher. I have seen wheels not being set into the bogies properly and bogies not being in the carriage properly. Something is causing the difference.
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Offline Bogenschütze  
#7 Posted : 14 February 2021 21:53:28(UTC)
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Bogenschütze

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Joined: 10/09/2019(UTC)
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Location: England, Chichester
I'm wondering if the body of the coach on the left has been pushed too far down over the underframe. When assembling the body on the underframe, the sides of the coach are flexed out to allow it to "click" into the correct position but I guess it's possible to push it too far. The buffers are attached to the body so that could explain why they are slightly too low and fouling the couplings.
Marklin - "The train set I never had as a child."
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Offline Copenhagen  
#8 Posted : 14 February 2021 22:21:17(UTC)
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Copenhagen


Joined: 23/04/2019(UTC)
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Location: Copenhagen, Denmark
Yes, if you place a ruler along the top or bottom of the right car you can see that the left car is at an angle down towards the other.
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Offline hxmiesa  
#9 Posted : 14 February 2021 22:54:32(UTC)
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hxmiesa

Spain   
Joined: 15/12/2005(UTC)
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Location: Spain
Originally Posted by: rhfil Go to Quoted Post
If you look very closely at the NEM sockets they appear to be even

I don't agree. I clearly see the pocket being lower on the left, than on the right. The pair of couplers are not horizontal.
Problem is probably between the bogie and chassis on one of the wagons.
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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Offline mike c  
#10 Posted : 15 February 2021 00:32:53(UTC)
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mike c

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Joined: 28/11/2007(UTC)
Posts: 7,898
Location: Montreal, QC
A long time ago, I decided to replace the Maerklin or Roco couplers on all my push-pull trains with Fleischmann's Profi Couplers.
This solved the problem with couplers and buffers.
There is a current conducting version of the Fleischmann couplers from Viessmann.
They are, however, not designed for use with Maerklin's contacts and are sold with a wire lead attached.
There are several brands of current conducting couplers. None that are designed for the Maerklin contact system.
The problem with wired couplers is that the wiring can sometimes interfere with the coupling shaft mechanism.

As far as the coaches, you can see that the one on the left is lower at the buffers, at the gangway and at the roofline.
The first test you could try would to to rotate one coach 100% to see if this resolves the issue.
On the Maerklin coaches, you should be able to push on the buffers to get them to retract against the coach body.
I don't think that the shells are pushed down too far on the chassis, as the coach has to be at a certain height to insert the gangway part into the shell, which holds the body on the frame.
What I am wondering is where you put the slider and ground contacts and if they may be lifting one of the coaches a little higher than the other?

Regards

Mike C
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Offline Tie  
#11 Posted : 15 February 2021 07:53:35(UTC)
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Tie

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Joined: 28/09/2019(UTC)
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Location: Rogaland, Haugesund
I have sern that on a few of my cars when going downhill in R360 curves the contact plates on the buffers pushed past each other and hooked each other at the end of the curve causing de railing when the train should straigthen out. Not Marclin cars though.
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Offline H0  
#12 Posted : 15 February 2021 09:57:43(UTC)
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H0


Joined: 16/02/2004(UTC)
Posts: 15,267
Location: DE-NW
Originally Posted by: Tie Go to Quoted Post
Not Marclin cars though.
I have this with Märklin freight cars. So this can happen with any brand. A design flaw in my case.

The problem with the double stock coaches shown here could be caused by incorrect assembly of one of the coaches.

Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline PeFu  
#13 Posted : 15 February 2021 13:08:08(UTC)
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PeFu

Sweden   
Joined: 30/08/2002(UTC)
Posts: 1,210
Originally Posted by: rhfil Go to Quoted Post
If you look very closely at the NEM sockets they appear to be even but the gap between the top of the sockets and the bottom of the carriages is different. Something is causing the right carriage to be higher. I have seen wheels not being set into the bogies properly and bogies not being in the carriage properly. Something is causing the difference.


Well, the purpose of my pic was only to show how close the coupler is to the buffer. The height of these cars vary depending if on straight or curve tracks, as well on horisontal or inclined tracks etc. Further on, the derailments occur between various cars, and even between the loco and the first car. This is the main background to my question on coupler alternatives.

Smile
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Offline H0  
#14 Posted : 15 February 2021 14:04:25(UTC)
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H0


Joined: 16/02/2004(UTC)
Posts: 15,267
Location: DE-NW
Originally Posted by: PeFu Go to Quoted Post
This is the main background to my question on coupler alternatives.
The Roco universal couplers work well with Märklin close couplers, but are lower and are less likely to collide with buffers.
See also here:
http://blog.mailez.de/eb...-couplers-for-h0-models/

In general Märklin makes the buffers high enough to avoid collisions with the Märklin close couplers.
The 7319 bar should also avoid the collision problem.
However there could be a different root cause and the derailment problem may persist even with different couplers.


Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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