BLI P70 - Correcting Coupling Distance How-To

[Lemosteam]

Speaking of the original post, @reinhardtjh graciously mailed two candidates for dissection and step/coupler mount redesign efforts, which will soon begin in earnest.

[nstars]

John,

I’m looping forward to your designs after out chat last week. 

[cbroughton67]

Chris Broughton: Is there a reason that you used MTL 1016s instead of 1015s?  It looks like your cars could stand to be even a little closer.  Thanks for posting this.

@dougnelson I went back and remounted 1015s on the first pair of cars, and completed the second pair using 1015s, adjusting the mounting position slightly for the shorter coupler. This closed-up the distance even more and looks even better. Good call, Doug!

Chris

[spookshow]

I still don't get how that's realistic. Is one expected to walk across the couplers?

-Mark

[learmoia]

At some point we need to account for the fact that it IS N Scale, and some liberties need to be taken for slinky effect on backup moves, uncoupling and reasonable layout curves...

Plus the diaphrams are modeled in the coupled position..  If the diaphrams were omitted or adjustable then appearance would be better.

.. or installed loose with alot of play and have them magnetically connected..

~Ian

[mmagliaro]

And if you put flexible diaphragms in there, it would completely connect the cars, like the prototype.  Maybe they are still a little more separated than real life, but they are about at the practical limit for model trains.

[Point353]

I went back and remounted 1015s on the first pair of cars, and completed the second pair using 1015s, adjusting the mounting position slightly for the shorter coupler. This closed-up the distance even more and looks even better.

Would you happen to have any of the MTL True-Scale couplers to try out in this application?

[bbussey]

@dougnelson I went back and remounted 1015s on the first pair of cars, and completed the second pair using 1015s, adjusting the mounting position slightly for the shorter coupler. This closed-up the distance even more and looks even better. Good call, Doug!

Excellent work Chris. American Limited diaphragms easily will traverse the revised distance.

[Maletrain]

I wonder why nobody makes a model of diaphragms that represent a pair of diaphragms between two coupled cars, so that it could simply be inserted between cars in a train to close the visual space with prototypical car separations.  They could be made flexible enough to go around tight curves if they were something like flexible foam with a skin.  Details cold be added to represent the rods and plates and still maintain the flexibility.  It would probably also help with the slinky effect.

While these would not appeal to the folks who want to do switching with passenger cars, I bet that is a small fraction of the folks who simply run their passenger trains through without switching, even at op sessions.

[robert3985]

I wonder why nobody makes a model of diaphragms that represent a pair of diaphragms between two coupled cars, so that it could simply be inserted between cars in a train to close the visual space with prototypical car separations.  They could be made flexible enough to go around tight curves if they were something like flexible foam with a skin.  Details cold be added to represent the rods and plates and still maintain the flexibility.  It would probably also help with the slinky effect.

While these would not appeal to the folks who want to do switching with passenger cars, I bet that is a small fraction of the folks who simply run their passenger trains through without switching, even at op sessions.

First, you have to understand how diaphragms function.  Just being "flexible" isn't enough for model trains, especially N-scale and smaller. 

If you watch a set of American Limited diaphragms attached to a pair of coupled N-scale cars as they go through various combinations of curves, you'll see that not only do they compress (which keeps them together) and flex, they also SLIDE against each other, horizontally and vertically as each car's trucks go over and through curved and uneven track.

This sliding of each cars' diaphragm faces against each other is essential for them to work properly and not cause derailments.

Saying that the thingy representing a diaphragm is to be "inserted" between cars after the train is coupled up is a HUGE understatement, omitting several steps to prevent knocking the cars off the tracks and to secure the part so that it doesn't come off while the train is running.  The sliding action would need to be incorporated into the piece, and that would take place on the interface between each cars' vestibule ends and the flexible piece, which is definitely not optimal and may not be reliable enough, since the piece would have to be both extremely flexible AND slippery on the ends, meaning it isn't going to want to stay in place because there wouldn't be any centering device attached to the car vestibule openings meaning the piece would eventually work its way either right or left and fall off somewhere.

Additionally, you'd be adding another precise operation to coupling up a passenger train involving delicately inserting a small, extremely flexible and slippery part between two passenger cars.  Multiply that operation by the number of passenger cars in the train and it could be a very tedious and frustrating thing to do.

Soooo...why fight a good thing?  American Limited already has several reliable models of passenger car diaphragms, which involve minimal modification of the cars and simply work by coupling up the cars. Simple, and good-looking too.

Cheerio!
Bob Gilmore

[Maletrain]

I do understand the sliding aspect of the separate diaphragms on the coupled cars.  That is most important on S curves, such as encountered in yard ladders and crossovers.  I have actually stood in prototype cars being switched and watched what the diaphragms do on S curves.  Given our tighter model curves, I think that is the biggest challenge for what I suggested.

But, some folks seem to have already made accordion-fold paper inserts and stuck them between coupled cars.  I am just suggesting that something similar but more realistic could be made and would probably be at least as popular as many of the other "detail parts" now for sale, perhaps including the American Limited versions. 

As for tedious installation - I think that what I am suggesting would be a lot easier to install than a pair of American Limited diaphragms.  You could probably insert a portion that fits inside the door on one car, then push the cars together so that they couple and at the same time, an identical portion fits into the door of the other car.  Of course, you might have to cut off any cast-on rigid representations of diaphragms from some manufacturers' cars for either case.

[bbussey]

It’s not difficult to mount ALM diaphragms on passenger cars.

[thomasjmdavis]

I wonder why nobody makes a model of diaphragms that represent a pair of diaphragms between two coupled cars, so that it could simply be inserted between cars in a train to close the visual space with prototypical car separations.  They could be made flexible enough to go around tight curves if they were something like flexible foam with a skin.  Details cold be added to represent the rods and plates and still maintain the flexibility.  It would probably also help with the slinky effect.

While these would not appeal to the folks who want to do switching with passenger cars, I bet that is a small fraction of the folks who simply run their passenger trains through without switching, even at op sessions.

I would suggest that while the majority of modelers "simply run their passenger trains without switching", the small fraction who do switch passenger trains are often the same people who make up the tiny fraction of modelers who go to the trouble to install after-market diaphragms.  Everybody I know who "simply run their passenger trains" just take them out of the box with whatever representation of diaphragms the manufacturer chose to give them, and put them on the tracks.

[Maletrain]

It’s not difficult to mount ALM diaphragms on passenger cars.

Well, I am going to have to disagree with that.  Assembly of those diaphragms is tedious, at best.  And, they need to be glued to the cars after whatever rigid representations of diaphragms have been removed.  Plus, they look a bit over-sized to me on their striker plates.  What I am suggesting would at least by pass the assembly and gluing, even if the rigid diaphragm removal is still needed. (Some models just have snap-out parts for diaphragms.)

Heck, Atlas is almost there with their rubber diaphragms on their new shorty cars.  But, those are molded to look like bellows or collapsible straws, not railroad car diaphragms.  How hard would it have been to make them look more realistic?

[wazzou]

Well, I am going to have to disagree with that.

Noticing a real trend here...