BLI is using RMR (Arnold/Vlk) couplers for their recent N scale models

[ncbqguy]

All the iterations of the RMR coupler drawings had the oval shaped gladhand because it needs to be in the proper orientation and there wasn’t any obvious improvement required there. 
Charlie Vlk

[peteski]

All the iterations of the RMR coupler drawings had the oval shaped gladhand because it needs to be in the proper orientation and there wasn’t any obvious improvement required there. 
Charlie Vlk

Well, Arnold messed up then, because their version used round gladhands, and they can easily be twisted out of alignment.

[ednadolski]

Well, Arnold messed up then, because their version used round gladhands, and they can easily be twisted out of alignment.

Does that mess up just the magnetic operation or anything else?

[peteski]

Does that mess up just the magnetic operation or anything else?

That is correct, plus it looks bad. But those pins can also be easily rotated back into alignment.  Some modelers just trim them off (on MTL couplers). Same can be done for the RMR coupler (since except for the shape of the coupler, it is identical to MTL split-shank couplers, like a 1023.

[Jim Starbuck]

 I wonder if the reshaped the inner surface of the coupler to better couple with standard N scale MTL couplers (I noticed slight coupling problem when I tested the Arnold SW1). I shaved of small amount of the inner surface for much smoother coupling action.

Peteski,

Could you elaborate on your improvement on the RMR couplers?
I have these mounted on a couple of my small switcher builds. They’re great because of the short coupler box and the operate pretty well, I’d be interested in whatever improvements could be made.

Thanks,
Jim

[peteski]

Peteski,

Could you elaborate on your improvement on the RMR couplers?
I have these mounted on a couple of my small switcher builds. They’re great because of the short coupler box and the operate pretty well, I’d be interested in whatever improvements could be made.

Thanks,
Jim

The only experience I have with this coupler is on the Arnold SW1 model.  As for "improvement", it is not really an improvement, but slight modification I felt was needed for smoother coupling with standard MTL couplers.  I describe the problem in my SW1 review (at the bottom of this post) : https://www.therailwire.net/forum/index.php?topic=37191.msg445405#msg445405

Here is the relevant quote from that post:

The coupler follows the typical split-shank design utilized in many MT (Micro-Trains) N scale couplers.  But the coupler head itself is quite a bit smaller than that of the the MT coupler.  Here is the Arnold coupler on the left, with N scale Micro-Trains coupler on the right.  Appearance-wise the Arnold coupler's shape and size is closer to the prototype knuckle coupler.  But the overall molding quality is not quite up to MT standard. The surface of the Arnold's parts is rougher, the mold draft angles seem to be a bit larger, and there is some flash on the parts (a piece of flash is visible in the photo above).  Also, the metal uncoupling pin is round in cross section so it can easily rotate out of proper alignment. MT uncoupling pins have flattened shape so they cannot rotate out of alignment.


There also seems to be a bit of a compatibility problem between the Arnold and MT couplers as shown in the above photo.  I'm surprised that this was not mentioned when the U25C (which was the 1st model to use this coupler) was introduced.  While I have not yet tested this model on a layout, I clearly see this problem on a piece of test track on my work bench. As the above photo shows the opening inside of the Arnold coupler knuckle is too shallow. The MT coupler hits the back of the opening and the knuckles do not clear each other to couple properly.  If some force is applied to shove them together (or if one of the couplers is swung slightly to the side then they will couple. But a gentle-coupling doesn't seem possible. I guess I will have to test this loco on a layout to see how well it will couple to other brand knuckle couplers.  This problem might also be fixable with some small trimming of the Arnold coupler. I will revisit this coupler in more details in the future.  It is a good looking coupler - too bad that it doesn't seem to work very well. I think that the opening behind the knuckle probably only needs to be about 0.005" deeper for it to work more reliably with MT couplers.

UPDATE:  I tested the loco on a layout and it did not easily couple with MT coupler-equipped cars. I The couplers had to be slammed together hard to get the couplers to coupler.  But the Arnold couplers easily coupled to Accumate couplers.  Those were the only 2 kinds I had handy to try.



As afar as the modification for smoother coupling with MTL couplers goes, I just took a hobby knife with a new #11 blade and carefully sliced of some plastic in the red areas of the photo. Doesn't take much. I took very thin slice, then checked how it couples with MTL coupler. After few iterations, the MTL coupler was able to smoothly couple with the RTR coupler.

[peteski]

Additional discussion about the RMR coupler took place in https://www.therailwire.net/forum/index.php?topic=52217.0  and I'm copying the pertinent info here.

A number of years ago I shared the RMR coupler with Broadway Limited Imports.  They never commented on it.  It apparently appeared on the USRA 2-8-2 which was released after they no longer were a client. 
I don’t know any of the details of how they implemented the design; I’m glad to hear it works well.  Too bad it isn’t on any other models...
Charlie Vlk
Railroad Model Resources

Well, that thread I pointed you to is about the RMR coupler.  Only 2 manufacturers so far have used that design: Arnold/Hornby and BLI.  I think each company "rolls their own" instead of getting them from some 3rd party supplier. Also, while the design of the head looks similar, Arnold uses a split shank and slinky spring like MTL couplers, while I believe BLI uses plastic whiskers (I'm just speculating because I don't own any of the BLI models with those couplers).

The problem with RMR is that neither company makes those couplers available as anything but replacement parts for their models.  No individual or bulk packs are available.

Peteski-

You are correct on all of your observations.

Both Mark (aka Elgin Locomotive Works) and myself (Railroad Model Resources) are still actively developing and promoting the coupler.  I developed the outline specifications and basic concepts and Mark has made them into 3D engineering drawings.  We have refined the designs over (too long of a) time wrestling with contour, springing and other details. 

If it becomes commercial we will allow our clients to make their announcements per our roles as consultants to the Model Railroad Industry.

Charlie Vlk

That's good to know Charlie - thanks for the update.  First, the ProtoMate coupler development seems to be progressing and now RMR.  That's a good news all around.

[ncbqguy]

Again, all iterations of the coupler DESIGN include flattened wire trip pins to prevent rotation.
Charlie Vlk

[Cajonpassfan]

Thanks Charlie, noted. It seems the flattened pin fell victim to the exigencies of production…
I must say though, I have four of the BLI mikes and so far the pins are staying put (fingers crossed).
It’s a great looking coupler, and I’ve yet to experience an unwanted uncoupling. I’d love to see these available separately for use on other rolling stock. I’m enclosing pics to stimulate some discussion and perhaps interest?
Otto

[Cajonpassfan]

A comparison with an MT (reefer) and Atlas clone.

[ncbqguy]

Peteski and Otto-
Thanks for the Hornby / Arnold fix and the photos of the BLI version.
Charlie Vlk

[peteski]

Again, all iterations of the coupler DESIGN include flattened wire trip pins to prevent rotation.
Charlie Vlk

Not quite. The Arnold/Hornby version on SW1 uses round wire which easily gets out of alignment. I have mentioned this "feature" few times (in the SW1 review, and in RMR related threads). Or it the wire is slightly out of round, the flat area is so small that it does not prevent the wire from rotating.

[ncbqguy]

I said DESIGN, not implementation.
Charlie Vlk

[peteski]

I said DESIGN, not implementation.
Charlie Vlk

Ok, so Arnold/Hornby did not adhere to the design.  My fault. I misunderstood your statement.

[Rasputen]

Here's a few more images of the BLI Mikado coupler.  On the tender, the coupler box is integral with the tender floor.