The Slinky Effect

My fleet of MTL rolling stock behaves more like a tree dwelling caterpillar than a train on rails because of all the play in the couplers. Is there a reasonable way to remove some of this slack from the couplers, or am I better off to put weights in each car?

Joshua, Here is the deal. For decades Z has had the slinky affect. Many through the years have added weight which of course shortens the overall train. A couple of years ago MTL announced they would no longer sell their couplers to the other 'cottage' industry modelers. As in any Capitalist society individuals and companies have come out with new couplers and trucks. AZL has great coupler that will not uncouple if your track work is good. Bowser, (Bowser Bucklers) has come out with a very popular Bettendorf truck with their version of a coupler. It is similar in looks to AZL's, and quite interchangeable with MTL and AZL couplers. AZL is also compatible with MTL. The main difference is that the Buckler and the AZL couplers will not uncoupler using the MTL magnet system. That is patent protected. Bucklers and AZL use the 'hand of god' method of uncoupling. Also AZL and Bucklers take a bit more speed to couple. The other difference is that AZL and Bucklers have eliminated about half of the slinky effect. In our scale that half is quite a noticeable improvement and is probably as good as it will ever be. Bottom line: Many modelers, myself included are saving our pennies and switching our rolling stock over to Buckler couplers/trucks/steel wheels. Right now I can't swear that AZL sells the coupler/trucks/steel wheels separately. Steel wheels allow longer trains and look real. For those who must keep there MTL trucks they are using Fox Valley steel wheels. On the other hand because steel wheels are so 'smooth' they do nothing to prevent the slinky effect and that is why there is still some effect. Me personally? Only lack of funds is preventing me from changing to either AZL or Bucklers tonight. Bottom-Bottom line: As in most things we have to learn to compromise. Since MTL made their decision, rightly or wrongly, we now have many more choices and if you don't need the MTL uncoupling method, then I think their decision has enhanced the running and pulling capablities for all Z scalers who decide to 'go steel'. Cheers, Jim CCRR

My quick recommendation is to find your heaviest car, and always put it at the end of your train. This helps some.

You can also use an MTL spring that goes into the bearing point of one of your axles to provide a bit of drag at the end of your train. Many have used these on MTL cabeese to minimize the slinky effect.

When we run coal at shows, I just pick one or two FR coal hoppers to put at the end of the train, because we don't often run a caboose. If we're running mixed freight, I put an Alan Curtis Flat or some other heavy car near the end, and it usually works well.

Your mileage may vary, of course.

I'm afraid, the cars and couplers are just fine, but your locomotive or your track work (or both?) is (are) the trouble maker(s). At the train shows the "slinky effect" is a good indicator of a missing cleaning session.

Lajos

zthek wrote:

I'm afraid, the cars and couplers are just fine, but your locomotive or your track work (or both?) is (are) the trouble maker(s). At the train shows the "slinky effect" is a good indicator of a missing cleaning session.

I must disagree. Track, train and all wheels can be absolutely perfect--indeed the track can be dead level--and the slinky effect can still happen.

The problem is this: tiny variations in friction from one set of wheels to the next cause very slight changes in tension as the train moves. This can happen anywhere in the train at any time. These changes in tension will cause the springs in the couplers to react. Springs happen to have the effect of amplifying their own motion, and the behavior of one spring will be passed on to others in the train. Before you know it, the whole train is oscillating. Now, if you add some irregularities in the trackwork (which is almost unavoidable), things will be that much worse.

You can see a similar effect in action on automobiles that have bad shock absorbers (which is a misnomer, as they do not absorb shocks). When the car encounters the slightest irregularity in the road surface, it starts bouncing. Soon it can be bouncing so wildly that the car can lose control (which is why bad shocks are dangerous).

So please don't automatically assume that the slinky effect means you've done something wrong. Granted, it's always a good idea to be sure your trackwork is free of defects, and that the rails and locomotive wheels are clean. Adding weight only changes the period of oscillation (and reduces the length of train you can pull). The trick of adding a spring to one of the caboose wheels can be effective, but it's not a silver bullet. If at the end of the day you still have a caterpillar creeping down the track, the problem is the couplers, and then the only solution is to change to another coupler type, if it's feasible.

...and then the only solution is to change to another coupler type, if it's feasible.

What? I smell some bias here. Nothing wrong with the MTL couplers. I ran 30+ car trains at train shows all day long without this "sophisticated" thinking. I can't repeat enough, when you have a "jerking" locomotive, you have the "slinky effect".

Lajos

David is absolutely correct. If you really want to have some fun testing the slinky affect, put together a 50+ car train that has MTL couplers. Start moving the first car slowing and see how long it takes the last car to move. The longer the train, the great the slack factor. This has been a long know issue in the Z world and has absolutely nothing to do with maintenance. It is clearly defined by the coupler design which is not rigid and has some play.

The AZL and Bowser Bucklers are a rigid truck and thus do not have the slinky affect. This is a factor that both manufacturer play up in their marketing for their products. To clarify Jim comments, AZL does offer trucks separately. AZL offers roller bearing truck 90001, roller bearing trucks with medium shank couplers #90004 and Bettendorf trucks #90011. The Bowser Bucklers are only Bettendorfs.

To counter act the slinky affect, I have also done what Bryan has suggested. A heavier car at the front and rear can definitely help to reduce the slack factor. FR cars are ideal for these do their extra heft. I also find mixing in cars with AZL couplers or Bowser couplers can help. Since these couplers are all compatible, it is easy to mix and match.

Rob

No, David is not right. He never ran long trains all day long, I did. He did some testing in the behalf of an interested party, while I remained independent. Don't try to justify non uncoupling "couplers" with this silly explanation.

Lajos

zthek wrote:

No, David is not right. He never ran long trains all day long, I did. He did some testing in the behalf of an interested party, while I remained independent. Don't try to justify non uncoupling "couplers" with this silly explanation.

"Silly"? Lajos, I'm not quite sure what your point is in taking issue with what I have to say, but I strongly advise you to back off. For one thing, I have no idea how you can be so certain what I have and have not done with model trains.

I have indeed run countless trains of every conceivable length (from 2 to 100+) over all manner of track for the last 40 years. I have measured, tested, analyzed, studied and experimented at great length with Micro-Trains and other couplers practically since they were introduced. I have joined forces with other very learned modelers (including physicists and mechanical engineers) to determine the underlying physics at work, and why these things behave the way they do. Spring oscillation is a very well-understood phenomenon, and that is the core physics underlying the slinky effect.

Furthermore, I speak not out of loyalty to any "interested parties," and I take great umbrage at your suggestion that I am biased in my analysis of these products (my critical analysis of the Bucklers, which I shared with its developers, was not very kind, if that is of any consequence). The simple fact of the matter is that Micro-Trains couplers have the slinky effect because there is a spring placed between the coupler and its mounting, thereby putting it directly in line with the linear forces applied to a train when under tension, which is an unfortunate circumstance. The other couplers have no such spring, and therefore have no slinky effect. It is as simple as that.

What is true is that the longer the train, the less this effect is noticed because the drag will increase, forcing the springs to remain compressed. For the typical modeler who has much shorter trains, the effect will be more noticeable, and for very short trains the effect is very pronounced, and there is little that can be done to prevent it under all operating circumstances. I have seen the slinky effect with a perfectly smooth-running locomotive on dead flat track. If every wheelset had precisely the same friction coefficient, then we would not see it; but minute variations in friction--which are unavoidable--can create oscillations, and if one car oscillates, they all will after a short time.

I also take you to task over the definition of a coupler. Yours is one based on a personal opinion that they must behave a certain way, and I truly believe you are the one who is biased because non-Micro-Trains couplers do not fit your personal criteria. But the truth of the matter is that couplers only need to connect cars together, and this is as true in the real world as it is in the model world. You can call them anything you prefer, but they are, at the end of the day, all still couplers. Deal with it.

Lajos, I am not sure why you think David is not true and acting out of bias. David has never been asked by AZL to design and test products. AZL has used his independent finding to improve their products, but this was after his review. Out of full discloser, I can say AZL and Full Throttle have supplied David samples, but there were no expectations associated with this. It was provided to show improvements to products based on his very thorough review.

Secondly, both Bryan and myself have concurred with his findings. I have been using MTL couplers since 1988. I know them very well, both for short train and long train operations. As you will see in my above post, I am not pushing folks to switch from MTL. Frankly, I always liked the look of the slack being removed from a long train as it starts to move.

But please drop the whole bias play. The Z world is getting tired that every time their is a perceived criticism of MTL, a group of folks have to rush forward and play they MTL versus the world card. It is getting bore-some.

I for one am not being critical. But the play in the MTL couplers has been known since day one. Is it an issue? It doesn't bother me and I have no plans of switching my MTL rolling stock to AZL or Bowser. It is up to what the operator prefers. I mix and I match and I happily run my trains.

I will agree fully that an engine that runs jittery will enhance the slinky affect. The same is true with imperfect track. This will cause a hesitation that makes the slinky affect more noticeable. But again, alternate products are more rigid and thus do not have the slinky affect. Of course, good locomotive maintenance and smooth track should be a goal for all of us.

Now if you really want to see something fun, put a string of Marklin German two axle gondolas on the track, the very short ones. The spring actually forces the car to sit on the track at a slight angle. It is quite strange to see.

Rob

zthek wrote:

...and then the only solution is to change to another coupler type, if it's feasible.

What? I smell some bias here. Nothing wrong with the MTL couplers. I ran 30+ car trains at train shows all day long without this "sophisticated" thinking. I can't repeat enough, when you have a "jerking" locomotive, you have the "slinky effect".

Lajos

Possibly, but myself I agree with Dave Smith: I've the feeling that my track work is OK as I run and switch 20-car trains without a hitch. I've no reminds of having experienced any derailment until now. My motive power consists of MTL Geeps and AZL 6-axle diesels that are anything but jerky.

But, but, but, when running my 3% slopes downgrade, that's true, trains have a caterpillar-like way of moving.

As my main goal is switching duties I don't plan to swap my MTL trucks with AZL's or others (on the opposite, I'm thinking about swapping factory trucks on my AZL cars with MTL samples in order to be able to uncouple them with magnets/electromagnets).

That's why I'm thinking towards "springloading" my MTL truck's axles to avoid this slack action.

Dom

It a bit discouraging when I see group members taking shots at each other.

Lets visit the prototype. Have any of you driven a train or worked as a conductor or brakeman. I haven't either but I did live next door to a NYC Engineer for 10 years and enjoyed our Saturday sessions telling me about his experiences going from firemen on steam to engineer and then on to diesel while operating my layout. One thing he commented on was how realistic my n-scale was at that time, in the fact that the train stretched out over hills and bunched up in the valleys just like the real thing. He said that in early days before cushion couplings a 50 car train had at least 50 feet of slack in it with all new couplings but the average was closer to 70 feet and if as the engineer he did not ease his way out onto the main he would probably pull a coupler on a car near the end of the train and if that did not happen your conductor would ride your behind for spilling his coffee in his lap in the crummy (caboose). I got to ride in the cab with him on his last ride and you can feel the slack going out and coming in pulling a string of 80+ cars with 3 units on the head end. His last ride was long before FRED arrived as there were two up front plus me and two back in the caboose. We did Buffalo to Rochester and return.

Anyway we had allot of fun on my n-scale empire while he was living next door. He always ran my Concor Hudsons as that was his favorite engine of the steam era.

I am a fan of what ever coupler works best as long as it looks like a knuckle. Even in N-scale there was controversy over Kadee as they were originally known and Unimat and the Kato versions.

In Z I have examples of Bowser, AZL and MTL and I do not worry about the slack. I am not a fan of putting a heavy car at the end of the trains as it usually leads to a spill on tight curves if you are pulling a long string or cars, but I have several cars and caboose with original Nelson Gray trucks and wheels and placing one of those near the rear tends to keep the train stretched out, and it works particularly well with the new metal wheels. As to whether there is less slack using Bowser or AZL I can not say as they are all mixed together in any consist I run. But I can see where the Bowser and AZL would allow longer strings of cars to be pulled with less chance of coming apart. The MTL couplers that I like best are the body mounts and many of my MTL cars have been converted to this style and I have added weight to others to get better running in long trains and being able to back a train through a switch or switches in my yard doesn't work if the cars near the head end have talgo trucks with couplers. I would like to see the Bowser and AZL couplers appear as body mounts also, but I feel I am in a minority that would like to see this.

Why he body mounts? As many of us have noticed that with any long string of cars couplers tend to ride up so that they are an easy candidate for uncoupling at any anomaly in the track work. With Talgo trucks the fact that they are free to rotate and rock means that this pull up can happen easier than with body mounts. With body mounts the body of the car is far harder to pull up so only the clearances in the pocket allow for movement. Plus I also have a file which I use to clear out behind the knuckle removing the parting line from the casting which also lessens the probability of the coupler riding up or down under strain of a long train. So my operating procedure is longer heavier cars with body mount couplers to the front and lighter cars with talgo trucks and couplers to the rear. The other item with the MTL couplers is the trip pin. They have to be adjusted on each car purchased or they snag the track. With the Bowser and AZL couplers these pins are not present so require no adjusting before going into service unlike MTL.

I am sure we are going to see more improvements in coupler design over time and it will be interesting to watch. I certainly would like to see some really long trains running at shows like I used to see on the n-scale Ntrak layouts.

Possibly, but myself I agree with Dave Smith: I've the feeling that my track work is OK as I run and switch 20-car trains without a hitch. I've no reminds of having experienced any derailment until now. My motive power consists of MTL Geeps and AZL 6-axle diesels that are anything but jerky.

But, but, but, when running my 3% slopes downgrade, that's true, trains have a caterpillar-like way of moving.

As my main goal is switching duties I don't plan to swap my MTL trucks with AZL's or others (on the opposite, I'm thinking about swapping factory trucks on my AZL cars with MTL samples in order to be able to uncouple them with magnets/electromagnets).

That's why I'm thinking towards "springloading" my MTL truck's axles to avoid this slack action.

Dom

Body mount your couplers for better switching operation and use metal wheels to improve their operation even more.

cheerz Garth

One thing he commented on was how realistic my n-scale was at that time, in the fact that the train stretched out over hills and bunched up in the valleys just like the real thing. He said that in early days before cushion couplings a 50 car train had at least 50 feet of slack in it with all new couplings but the average was closer to 70 feet

It's even worse in 1:1, you need that slack to get going.

Well, I'll admit my track isn't perfect. This is, afterall, my first layout. But the AZL diesel runs nice and smooth. The longest train Ive run so far is fourteen cars. I have to say the heavier cars, like the husky stacks, run nicer with less oscillating. As nice as the other truck and coupler options may be, however, Im not willing to give up the magnetic uncoupling.

Im not willing to give up the magnetic uncoupling

Announcement: Great victory for common sense against sophisticated b.s.

Lajos

In that 1-1 scale you should see the slack action in a loaded tank car that has just come to a stop. It can slosh back and forth a couple of feet. That tank car can be a few cars away and still move the cars you are next to.

zthek wrote:

Im not willing to give up the magnetic uncoupling

Announcement: Great victory for common sense against sophisticated b.s.

In case you hadn't noticed, I never recommended any alternatives assuming one needed to perform switching. In this case, M-T is still the only option. And in which case the slinky effect will still be a problem. There are ways to reduce it, as previously recommended (a heavy car at the end of the train, springs in a truck in the last car, etc.). But if a modeler does not want to do switching, and are sick and tired of the slinky effect, there are now viable alternatives.

Folks, don't let Lajos' bluster fool anyone. As far as b.s. is concerned, I would go so far as to say he's become the prime source in this thread. He simply refuses to accept very obvious and factual information in his quest to trample any competing products to M-T. The "common sense" quip is the clue to his bias: it suggests that anyone who choses anything except M-T is somehow an idiot. His assertion is that anything other than an M-T coupler is not a coupler, and using a competing product demonstrates a lack of good judgment.

Lajos' offhand dismissal of the issue based on his experience at shows is not very informative. Running trains at shows and running trains on a home layout are two very different things. Most show layouts have no grades, and long trains on relatively flat track will have few problems. Shorter trains on a smaller layout, especially one with grades, will be virtually guaranteed to have problems. You need to be experienced in a wide variety of operating circumstances in order to realize where this effect will be the most pronounced.

Just to reassure, I have not offered any "sophisticated b.s." in this thread. Everything I have said is substantiated fact that I will back up with any amount of proof that one may desire. I'll wager, however, that no one here really needs any proof (notice that the majority of the replies align with my position), while Lajos will only manage to deliver some snarky quip in reply, if anything.

The fact is that M-T couplers can exhibit the slinky effect problem regardless of the condition of locomotive or track. M-T has even publicly acknowledged this as a known problem, and they are researching ways to address it. Some people do not desire magnetic uncoupling, and these people have options they can use to effectively eliminate the slinky effect, not to mention be able to run longer trains at shows without accidental uncoupling, another known issue with M-Ts.

My hope is that this discussion ends here before it gets any uglier. Lajos' pointless, indignant remarks aside, there should be more than enough real information to answer the original question.

I will have to agree with David. The MT couplers do not seem to experience the same problems on a flat layout opposed to a layout with grades. I have added metal wheels to some of the cars that I have and it actually has made the slinky effect in some ways worse especially going down a grade.

I run DDC and when going down a grade the cars roll so freely, that at slower speeds cause the cars to slam into the engine. This causes the BEMF to kick in on the enigine. Which in turn causes a ripple rubber band effect. The way I have combatted the issue is turn the BEMF off on the engines and place springs in the truck of the rear most consist. This is just a temporary fix. Later I will try to come up with a better solution.

Just my 2 cents, for what its worth.

Ed

Well, obviously this topic has more issues than it should have. I will commend both major participants for their views and 'restraint'. I will lock this topic. Participants can avail themselves of behind the scenes internet communication if need be. Thanks, Jim CCRR