Couplers

[Cajonpassfan]

I think the slinky effect is primarily an effect of cars being lighter than they could be.  Otherwise I just don't understand why some people seem to have different results than I do....

Ben, ummm, do you have hills and grades and curves on your layout?  I do...
Otto, slinking along with properly weighted cars...

[ednadolski]

I think the slinky effect is primarily an effect of cars being lighter than they could be.  Otherwise I just don't understand why some people seem to have different results than I do. 

Weight is one factor, but not the cause.  The slinky effect is a harmonic resonance.   It occurs because the couplers have a centering spring in them which will alternately store and release energy, rather like a pogo stick:

Resonance occurs when a system is able to store and easily transfer energy between two or more different storage modes (such as kinetic energy and potential energy in the case of a pendulum). However, there are some losses from cycle to cycle, called damping. When damping is small, the resonant frequency is approximately equal to the natural frequency of the system, which is a frequency of unforced vibrations. Some systems have multiple, distinct, resonant frequencies.

The springs in the couplers are what store and transfer the energy between potential energy (the compressed spring) and the kinetic energy (the motion of the cars).  To see the slinky, you have to have the right levels of energy storage and losses, which will vary with your exact operating conditions: number of cars, train speed, friction in the wheel bearings,  mass, grades, etc.

The drag springs work by introducing more damping, thereby altering the operating conditions.  But as I noted previously, as a "fix" that approach has a lot of drawbacks.  The real fix is to eliminate the centering spring from the coupler design, since that removes the ability of the system to store and release resonant energy.

Ed

[robert3985]

Thank you, Ed. Someone had to tell it like it is.

Like I said, I don't run extra long trains.  I also have never had even a hint of a problem with my cars falling off the track...even with superelevated curves.  I also run mostly Z-scale couplers, and their "slop" is much less than regular ol' N-gauge couplers.

If that's the way it is for Ed and DKS, that's the way it is. 

However, it's not that way for me, so that's the way it is too.

I guess that's another evidence for non-local reality eh?

Cheers!
Bob Gilmore

[Ike the BN Freak]

Another thing with the MTs is only certain couplers slinky.

1015s do not, as when you are pulling on them, the spring does not compress, where the 1023/1025 and truck mounted ones, have the spring behind the center post, so as the train is being pulled, the spring is compressed, causing the slinky.

So in theory, if you have a train of all 1015s, you could have a train with no slinky.

For me, I've just gotten used to the slinky and lived to deal with it until someone comes out with something better...until then I'll live.

[ednadolski]

I also run mostly Z-scale couplers, and their "slop" is much less than regular ol' N-gauge couplers.

I've also tried the 905s.   It's still the same design, just smaller, so the same problem occurs just under sightly different conditions (speeds, train length, etc.).

However, it's not that way for me, so that's the way it is too.

I'm glad for everyone who doesn't have to experience this.   For me tho the pogo (and the truck-mount problems too) had become enough of an issue that I had nearly given up on N scale, again because I have neither the time nor the desire to be constantly band-aiding these inherent design flaws.   While not perfect, the McHenry and FT couplers have made a huge difference for me, and I am really looking forward to the day that DKS releases his new coupler design.

It's really good to see that N-scale is moving forward and that there are solutions coming to these long-standing problems. I never found it acceptable to think of them as an inherent compromise that one must endure in order to model in N scale.   I see no good reason why N scalers should have to suffer with problems that are not an issue in HO or other scales.

1015s do not, as when you are pulling on them, the spring does not compress, where the 1023/1025 and truck mounted ones, have the spring behind the center post, so as the train is being pulled, the spring is compressed, causing the slinky.

So in theory, if you have a train of all 1015s, you could have a train with no slinky.

Not really.  Even with all 1015s, running a train downhill still will put the springs in compression (at least, if you have free-rolling cars).

Any case where springs are absorbing/releasing the in-line train forces, you will get a slinky under the right conditions.  Locating the centering spring before or after the center post just changes the resonance point, but doesn't make it go away.

Edit:   BTW I'm not meaning for this to sound like an MT bash in any way,  I just think that unless the cause of the problem is understood, it isn't really possible to come up with ways to fix it.   I think MT understands the concerns and it's good to see them taking steps like adding body-mounted couplers (and I do use my wallet to vote in favor of these).



Ed

[hpwrick]

Myself?   I give a thumbs up to Micro-Trains couplers.    I espeacially like the "Slack" action of the couplers.    Prototype and as authentic as you are going to get.

[robert3985]

I agree with Ed and DKS that N-scale shouldn't have to "put up with" problems in basic operation which other scales do not suffer from.

But, I've accepted the fact that N-scale's lot in existence is to have certain design compromises that are long-due to get "fixed", such as dragging many N-gaugers (kicking and screaming) into the N-scale world by just accepting low-pro wheelsets, or converting the same bunch to N-scale "Kadees" way back when from their beloved Rapido monstrosities (remember "transition cars" with a Rapido on one end and a Kadee on the other when running with your club?).

I, like many others, know that MT couplers are far from perfect.  They're too big, they don't look prototypical, and they have a tendency to "slinky".  BUT, and this is important...they are the best that is available in this present day. 

Okay...not for every application, but for general freight car running and the couplers on engines which couple to freight cars, they are.

And, the Z-scale MT's are very close to the correct size for 1/160th scale usage and work just as good as their big brothers as long as you're not pulling several hundred cars around at your local Ntrak meet.

All I can say is...hurry up DKS!

Cheers!
Bob Gilmore

[DKS]

All I can say is...hurry up DKS!

I'm on it, believe me. But I'm not in a rush, because something this critical cannot be rushed--not without taking an enormous risk.

Soon I will have a blog up and running for the coupler project, where I will share (what I can) about the project as it moves through each stage of development and production.

A very important step will be beta-testing, and it is here where I anticipate the most variability in production time, as it all hangs on how many iterations the design cycles through before the final product is ready.

If I cannot live up to all of my advertising promises--no slink, no blowups, best cosmetics, etc.--then it won't get released. However, I am confident that the design will meet these criteria. My patent attorney feels I have a good shot at this--he has been a tremendous source of encouragement.

[jagged ben]

Ben, ummm, do you have hills and grades and curves on your layout?  I do...

Our layout is about 80% hills and grades.  Steep grades too, some about 4%.  Curves are generally greater than 21" radius.  (What are your curves?  Maybe tight curves play a role here?)

In my experience the slinky is worst in the flat areas.  Also the longer the train the less of a problem.  I'm not discounting the comments from you and Ed, but I have to say they puzzle me because my experience has been the polar opposite.

Also, Ike is right that the 1015 has less slinky, and Ed is right that it still has some.

 

[amato1969]

I have used a small dab of vaseline in the body-mount MT's I have assembled.  It's not perfect, but does help dampen the slinkitude.  Tweaking assembled couplers is more difficult to remedy...

  Frank

[Cajonpassfan]

(What are your curves?  Maybe tight curves play a role here?)

Ben, the offending section on my layout is between Summit and Cajon that has a 3% downhill grade and 18" radii including a big es curve. It looks wonderful until you run a 25 to 30 car MT equipped train down that hill, and the rear half starts hopping and slinking to the point where nobody could possibly survive in the caboose...

I put two spring "brakes" on all my cabooses to provide a bit of drag, and generally that works pretty well elsewhere on the layout, even on the two percent downhill. I have no issues on flats or uphill running, but the 3% downhill is a problem. I'd have to turn the caboose into a sled and drag it along and even then you can't keep the slack stretched out.

I've tried putting springs in a handful of cars throughout the train, and while that helps, it creates other issues. Mine is an operating railroad, with cars being reshuffled randomly when trains are rebuilt and I really don't like the notion do having to build trains around the need to have a "brake car" every so many. Besides, I find adding artificial drag counterintuitive, it's just seems wrong

Having said all this, I still think the MT is by far the best we have and until something better shows up, that is my defacto standard. Not whining, just sayin...
Otto

[NorsemanJack]

Mine would be "mostly Kato," as most of my locomotives and all of my passenger cars have Kato couplers.  I like the accumates on the Atlas locomotives, where they are screwed on (no expoding).  Also, the only time the slinky MT ever has bothered me is when I have them between locomotives, which I no longer have except for the single instance of between the B units on an IMR FT ABBA.  I've been meaning to upgrade those to Red Caboose dummies.

[Ike the BN Freak]

Also, the only time the slinky MT ever has bothered me is when I have them between locomotives, which I no longer have except for the single instance of between the B units on an IMR FT ABBA.  I've been meaning to upgrade those to Red Caboose dummies.

I don't think that is slinky between locos, but more of the differences between motors and locos.

[Mark5]

I'm on it, believe me. But I'm not in a rush, because something this critical cannot be rushed--not without taking an enormous risk.

Soon I will have a blog up and running for the coupler project, where I will share (what I can) about the project as it moves through each stage of development and production.

A very important step will be beta-testing, and it is here where I anticipate the most variability in production time, as it all hangs on how many iterations the design cycles through before the final product is ready.

If I cannot live up to all of my advertising promises--no slink, no blowups, best cosmetics, etc.--then it won't get released. However, I am confident that the design will meet these criteria. My patent attorney feels I have a good shot at this--he has been a tremendous source of encouragement.

Excellent.

[tom mann]

Nothing until NZT's arrive.