Jim Kelly -"The case for body-mounted couplers"

[rogergperkins]

The May 2013 issue of MR contains this nscale insight article.
The conclusion is that body mounted couplers work better than truck mounted couplers.

The only test of this hypothesis that I can do is to back a train of MTL heavy weight passenger cars (with body mounted coupler from the factory) around my layout to determine if they work without causing derailing.

I tried it with qualified success. I noticed after I backed the train around the layout and into the yard which involves going from Atlas True-Track to Kato Unitrack through a double crossover and a #6 turnout or two that mid train the back truck of one car had derailed. The car was still on the track.

What is your experience with body-mounted couplers?  Thanks.

[benderda]

Smallest radius curve I use is 11" and all running is done behind steam locomotives or 4 axle deisels.  No problems what so ever.  I much prefer body mounted couplers. 

[Erik W]

I use Z scale body mounted couplers on all my rolling stock (about 150 cars/locos) and have never had any problems.  I even ran a 50 car train to see if I would have any issues with derailments or unwanted uncouplings, but couldn't get anything to come uncoupled or derail.  Normal train length for me is 18 or so cars.  Backing isn't a problem either.

I'm a big advocate of Z scale couplers on N scale rolling stock. 






Erik

[rogergperkins]

I backed a second passenger train with MTL heavy weight cars, three FVM wagon top boxcar and a Kato GS-4 locomotive. 
This trial resulted in derailing of MTL heavy weights as they reached the curve into the yard; they had gone through a double crossover and a #6 turnout.
Now the question is whether the cars derailed because of the couplers or some other factor such as shifted center of gravity from installing Easy Peasy lighting
strips in the roof.
I have a third passenger train with similar make up of cars and locomotive to test in the backing experiment.

[Zox]

While the majority opinion on The Railwire favors body-mounted couplers, truck-mounts do have a couple of advantages.

Despite Mr. Kelly's diagram in MR, the meeting angle between couplers on a curve will actually be less with truck-mounts than with body-mounts. This is because with truck-mounts, there's very little track between the rotational centers of the trucks, and therefore little opportunity for the track to change direction. With body-mounts, the rotational centers are at the centers of the cars, which are much further apart. This will be especially obvious on S-curves.

Also, on tight curves, when rolling stock with long overhangs (like the noses of E-units or some passenger cars) are coupled to shorter cars (like express boxcars), the difference in coupler positions relative to track centerline can cause body-mounts to push a car off the side of the rails.

This superior ability to deal with less-than-ideal track geometry is probably why truck-mounts have been favored for the hobby until recently. A newcomer to the hobby, whose train derails every time it goes from a 9-inch-radius left curve to a 9-inch-radius right curve, is less likely to blame his own design skills than he is the "stupid train." So sacrificing a little bit of absolute realism for a whole lot of fault-tolerance is simply good business sense. 

[Chris333]

I just read the article and all I can say is wow.

If jeweler's saws, pin vices, and taps are new to you, join the club. They were certainly new to me, and I suspect they are to most other N scale modelers, too.

WTF 

Stay cool and run steam     

[rogergperkins]

I continued testing the hypothesis of Mr. Kelly by backing a third passenger train with a FVM wagon top boxcar at the head end and MTL heavy weight cars as the remaining track; the locomotive was a third Kato GS-4.  I experienced some problems getting the train out of the yard, but over all the backing portion went fine.
Next I used two Kato E-8As in consist with a string of MTL 40 foot boxcars; the head end was one with a load.  These locomotives have MTL z-scale 905 couplers.
The head end car was the one that derailed during the backing.  By substituting a FVM wagon top boxcar at the head end for the head end MTL, the train could be back successfully around the remainder of the layout and back into the yard.
I used the same locomotive consist with a train solely of FVM wagon top boxcars and repeated the experiment.
The train went around my layout with no derailments.

Now my question is do I change all 300+ of the MTL cars from truck mount to body mount? 
I realize this experiment brings several variables beside the couplers to play.  The coupler trip pins may cause derailing, the quality and alignment of the track work can be a factor.  I am convinced that Mr. Kelly as a valid point in terms of performance and minimal derailing with body mounted couplers.

[davefoxx]

I'm pro-"body mount couplers" and am appreciating the movement by the manufacturers to offer more and more models with body-mounted couplers.  In my experience, truck-mounted couplers are less reliable.  This is a lesson that I learned thirty years ago when I was a teenager modeling in HO scale.  My Athearn cars (my first cars with body mounted-couplers in the 1980s) stayed on the track better than the Life-Like and Bachmann cars of that era.  That said, truck-mounted couplers can work fine, but, under certain conditions, e.g., reverse movements, cars and locomotives with body-mounted couplers perform better.  In fact, I have cars that have not been converted yet, like my tank cars and certain covered hoppers.  But, when push comes to shove (literally), they are often the culprits in a derailment.  Yes, it is also true that truck mounted couplers couple on curves better than body-mounts.  But, even the prototype occasionally has that problem.  So, I live with it.  Your mileage may vary.

DFF

[jdcolombo]

I've been body-mounting couplers on my rolling stock since 1994, first using MT 1023's, with the 1015 becoming my "standard" coupler since the early 2000's.  I prefer the more-realistic look, and also believe Mr. Kelly is correct on the operational aspects, especially when doing reverse moves on a train of any length through a yard ladder or any kind of mildly complex track work.

That said, truck mounts have and continue to work just fine for many folks (honestly, no one really backs a 20+ car train around their layout); the real problem is in mixing truck-mounts and body mounts - that's a recipe for disaster.  If you're going to go the body-mount route, you'll need to go all-in.

John C.

[jagged ben]

There are some tradeoffs...

On a sharp curve going up a steep grade (or with a really heavy train), truck mounted couplers are slightly less likely to string-line on long cars.    Try putting a Trainworx 85' autoparts car (with body-mounted couplers from the factory) and putting it in the first twenty cars of a 40 or 50 car train.  Now try to pull that train around a 21" radius curve on a 3% grade.  That Trainworx car tips over to the inside of the track, and you've to a runaway.  Move the Trainworx car to the back half the train, and you're fine.

Now try the same thing with an 89' Microtrains autorack, with truck mounted couplers.  You'll probably find you can put it a bit farther forward in the train without it derailing. 

And now, on the other hand...

Try backing a cut of 15 of those 89' Microtrains cars (TOFC or Autorack), with truck mounted couplers, through a yard ladder made with anything but the most finely made and maintained turnouts.  Not likely to meet with success either, as the wheels get twisted and pick the frogs, if not the points. 

The longer the car, the higher the stacks.   On 40' cars is hardly matters.   On 89' cars it can determine whether you can run them on the layout you have space for, say, if you are limited to less than 15" radius curves.     Coupling to like cars is easier than coupling to cars of different lengths.   Which you prefer, and on what cars, really depends quite a bit on the layout you are running on.  Are you doing more running around curves on grades, or more backing up cuts of cars in yards?  What's your minimum radius?  Do you like to mix your autoracks and TOFC into manifest freights, or are you happy running them in unit trains?  (Are you modeling 1975 or 2005?)   

I think that manufacturers should make an effort to provide a true option for both types of mounting on their RTR models, especially for car lengths over 60 scale feet or so.  By a true option, I mean no required modification of the car as manufactured, and totally reversible in either direction.   Just make it so the coupler box can pop off the truck and be screwed to a pre-drilled hole, (perhaps with a supplied shim, or removal of a washer from the truck, as necessary).  Maybe the truck has to be turned backwards.  If they sell the shim and screw separately, I won't even complain.  It really shouldn't be that hard. 

[GaryHinshaw]

jb's comments match my experience quite well.  I have some issues with body-mounts on long cars at the head end of long trains going upgrade through curves (string-lining), and I have occasional issues with truck-mounts at the head end of long trains going down grade through turnouts (picking points/frogs).  Fortunately, these issues are basically eliminated with dpu's.

[VonRyan]

I personally find truck-mounts to be reliable, the only issues i've ever had always comes down to an improperly shimmed turnout or trackwork where the gauge is not exactly 9mm give-or-take. Of course I also prefer deeper flanges over low-profile.
As of yet I've never had any issues backing trains of any length.

-Cody F.

[John]

Now my question is do I change all 300+ of the MTL cars from truck mount to body mount? 

One at a time ... I much prefer body mounts as well .. although I've seen some problems with Kato loco's and the car right behind it getting pulled off the track in a tight curve

[rogergperkins]

  I am now convinced that on my current layout that body mounted couplers have some distinct advantage over truck mounted couplers as tested by backing a train around the layout. This is a process that involves the train passing through 3 Kato double crossovers from Kato Unitrack to Atlas True-Track and through 3 True-track turnouts.  The layout is nominally zero grade.

However, by simply using a FVM wagon top boxcar with body mounted couplers as the head end car, I achieved the same results backing MTL boxcars. 
This leads me to believe that modifying a few cars for head end use to body mounted couplers would be beneficial. I do not have to modify all 300+ cars with truck mounted couplers. 

[nkalanaga]

Roger:  If your locos have body mounted couplers, the problem could be the difference in overhang due to length and truck spacing.  Even the prototype has that problem, and many roads restrict what lengths can be coupler together on sharp curves.  As an extreme case, an iron ore car and an 80 ft flatcar simply won't work!

A truck mounted coupler can be thought of as a very short car, and would be subject to the same limits.

For what it's worth, a pair of Kato SD40s don't go through a #4 crossover reliably, even though one alone will work fine.  The body mounted couplers won't swing far enough to allow for the overhang mismatch.  To be fair, I doubt that the prototype, as a single unit, would go through a #4 turnout at all.