Best Of Notes on body-mount couplers (work-in-progress)

[jagged ben]

If only that were the case, then I could have saved myself a heckuva lot of time and money.  Unfortunately, it really is like that, and it does it every time.  Anyone who doesn't believe the video is more than welcome to come over and see it in person.  And there isn't anything special about this set of cars, it happens on anything with MT couplers.  Ed

Do those cars also have metal wheels?  And are the wheels clean?  Are there flanges hitting spikeheads?  Are they well weighted cars?   Is the track in gauge? 

Ed it's not that I don't believe you or the video.   (I know we've butted heads over this before).  I used to get slinky like that all the time on my old layout with old Atlas cars and dirty plastic wheels (on code 80, if that matters).  But these days if I run a local at the club with mostly newer cars that come with more weight,  or with MT cars or Roundhouse cars with the metal underframe, (and all this on ME code 55), I just don't have those sorts of problems.  Sometimes I see it in the cabeese or the last car, less often the second to last car.  But usually I can switch a yard all day without thinking about slinkys.

I'm really just curious about this and trying to help you and others out.   (Not that I'm trying to short shrift the FT solution either, as it looks all good to me.  I guess I thinking more of others here who might not be ready to go that route.)



 

[ednadolski]

Do those cars also have metal wheels?  And are the wheels clean?  Are there flanges hitting spikeheads?  Are they well weighted cars?   Is the track in gauge?

- about 50/50 metal/plastic
- yes, most are new or nearly so
- nope, all are lo-profile flanges
- factory default weight
- yep (and freshly cleaned too)

usually I can switch a yard all day without thinking about slinkys.

No question, the problem is far less apparent on straight/level track, and with shorter cuts of cars.   It's just a matter of finding the right operating conditions that cause the springs to resonate.   Downhill, longer trains, mix of curved/tangent track, and low speeds seem to be main contributors.   Of course, these are the things that are in abundance on Tehachapi

Ed

[ednadolski]

The Z scale version is actually intended to be a "finescale" N scale version, and may be slightly smaller than existing Z scale couplers. Shank parts will be the same as the N scale version so they can drop into existing pockets.

Not sure I'm clear - do you mean that the Z coupler will drop into existing N scale pockets, or existing Z scale pockets (like the FT, or the MT905)?   If they drop into the stock FT Z pocket, then that would fit into these etched ones without any changes.

Thanks,
Ed

[GaryHinshaw]

The Z scale version is actually intended to be a "finescale" N scale version, and may be slightly smaller than existing Z scale couplers. Shank parts will be the same as the N scale version so they can drop into existing pockets.

David, thanks indeed for a peek at some of these specs - very helpful!  Do I take from the above note that the Z scale coupler will not fit the Full Throttle or AZL pocket, or do you mean same design as N, but smaller size?  If the former, that would be problematic for Z scalers (or for people who want to use these pockets).

It sounds like it wouldn't be a bad idea to draw up a pocket sized for Accumates that would then also transfer to Proto-mates.
-gfh

[DKS]

Z couplers would drop into N pockets. A version for Z pockets may be in the realm of possibility, but initially all shank parts would be identical, designed for the N market.

[GaryHinshaw]

From the 'because I could'  department (not to be confused with the 'because I should' department), I tried to reproduce Ed's slinky video, but I failed.  I set up an almost-the-same consist (we must shop at the same boutiques) and ran it down the same stretch of the Loop as his, but was unable to get any significant pogo action.  I did get a bit when the train was rounding the curve coming into that stretch, but nothing like what Ed is showing.  So I backed it up to the Tunnel section, which is on a very slight down-grade (where there is very little tension in the springs) and filmed a series of runbys at successively slower speeds to see if I could trigger a resonance.   The best I could do was on the last/slowest runby, which produced a modest pogo in the last 3 cars - here is the gripping evidence:

https://vimeo.com/57135979

If you listen closely, you can even hear the pogo.  Otherwise it is not very compelling video.  I am at a loss to explain why Ed's case is so severe.

-gfh

P.S. The cars all have MT couplers here - but probably a mix of front-sprung and back-sprung.  I didn't check.

P.S.^2 Thanks DKS.

[GaryHinshaw]

From the tank car rescue department, here is another body-mount example.  This is the Atlas 20K tank car I dropped last week:   



To mount these couplers, I removed the screw from the lug that holds the base to the tank, shaved it down a bit, until it was in the same plane as the bottom of the walkway, then screwed a pocket onto the lug with a 00-90 screw (which replaces the original screw just fine, and still holds the tank in place):



Fortunately, I was able to repair the busted walkway with some Plastruct Bondene:



and she's better than new.  Add some BLMA 100T trucks for a better ride height and we're done (except for weathering):



By the way, the factory wheels that ship with these cars are awful.  The tread is so rough, they feel like they're rolling on concrete rails.  And the mounting lug precludes one from swapping in MT trucks with couplers.  This body mount solutions works really well, I think.

-gfh

[ednadolski]

Wow Gary, that tank car looks great!   Nice repair job too!

Re: the slinky,  if you have a slight grade and little tension then I would expect it to be significantly less.  I'm speculating too that a mix of front/back sprung couplers might make a difference, as that could work to absorb some of the resonance.  The resonant speed will definitely vary with the exact makeup of the train as well as the track curvature and gradient.

For grins tho you might want to give it a try with say 8-10 autoracks, those have always given me trouble

Ed
 

[ednadolski]

Sorry if slightly OT, but now I think I must have seen it all:

How cool is that? 

Ed

[tom mann]

Just like how the real ones work!

[Mark5]

Just like how the real ones work!

Lol, yeah! (that's nuts!)

[Smike]

Sorry if slightly OT, but now I think I must have seen it all:

How cool is that? 

Ed

Nice find! Ok now I'm thinking, hum.....it will only take me 5 years to upgrade the couplers on all my rolling stock, then I can begin to source micro magnets....

[C855B]

This can be done in N. Here is one supplier with magnets small enough to work for N, http://www.bjamagnetics.com/html/micro-magnets.html, although pricing isn't mentioned.

The problem with this approach is it's "ended" because of magnet polarity. If you flip one of those cars in the other direction, both ends will not work, they will push the mating hose away. Cool idea in theory, but the reality of incorporating this into operations would be a pain in the tuckus.

FWIW, I can't find these on eBay. Don't know whether they're no longer listed or I'm fighting eBay's new brain-dead search engine.

[DKS]

The problem with this approach is it's "ended" because of magnet polarity. If you flip one of those cars in the other direction, both ends will not work, they will push the mating hose away. Cool idea in theory, but the reality of incorporating this into operations would be a pain in the tuckus.

Actually, you can make this work. The trick is to mount the magnets transversely, so that the poles face sideways. As long as they are oriented consistently (e.g., North is always pointing to the left), the magnets will attract. Used this trick to make close-to-scale couplers for T scale.

[C855B]

You know, I thought of that (or something similar) about 10 minutes after posting. The über-small cylinder magnets can also be polarized transversely if you're talking about a custom order, but keeping the N-S versus left-right orientation straight would be... uh... "fun".