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HORNBY DUBLO COUPLING CONVERSION


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I don't know if it was the case, but the maximum duration of a patent within the EU is now 20 years, provided the annual maintenance fees are paid

 

So if indeed it was filed in 1946, it would seem that Trix would only have had to wait (or pay licence fees) until '66.

 

Best

Simon

 

So it would appear the patent has expired.

 

As far as Trix were concerned, the UK wasn't in the EU in 1946 (it hadn't even been founded then) and, in any case, they had gone bust before 1966 (as had Meccano Ltd.).

 

I always find it strange that copyright lasts for life plus seventy years, whereas a patent (which is just as much intellectual property and more useful IMHO) is strictly limited in duration and expensive to set up and protect.

 

The later development incorporates delayed uncoupling (it works similarly to Kadees but has a one piece 'knuckle'). Unfortunately it won't couple automatically with Dublo couplings. though it works with Peco's early version. (The problem is with the actual size of the knuckle.)  http://www.peco-uk.com/product.asp?strParents=3309,3322&CAT_ID=3325&P_ID=17335

 

I can see problems with trying to make a NEM compatible version, which is probably why they dropped the idea.

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I can see problems with trying to make a NEM compatible version, which is probably why they dropped the idea.

 

The unexpected problem that I have encountered is this.

 

On the face of it, the flexible, self-centring NEM coupling mount - the one with the very thin section of shank - should be perfect for carrying a Peco coupling head.

 

So I cut the shank off a NEM coupler, leaving just the head and uncoupling tail. I then drilled and 12BA tapped the remainder of the shank, in line with the tail.

 

I took a NEM narrow coupler as fitted to current Hornby / Bachmann stock and removed the coupling head , leaving just the shank which I drilled 12BA clearance.

 

The Peco head was then screwed to the NEM shank, with spacing washers to adjust the height of the Peco head.

 

post-2274-0-90980200-1436653842.jpg

 

Having done this to a number of vehicles, they behaved perfectly when pulled. However, the pivotting action of the opposing coupling heads proved to be too stiff, even with the narrow flexible section of the NEM shank.

 

post-2274-0-50909200-1436653873_thumb.jpg

 

Pushing two vehicles together would simply propel the second vehicle rather than engage the couplings.

 

Similarly, because of a lack of freedom in the pivotting of the couplings, they would often disengage over pointwork.

 

One of the essential features of the Peco coupling is that is should be totally free to pivot, so that it can readily deflect sideways and engage, and swing with the curve so as to remain engaged.

 

One solution is to substitute the NEM shank with a strip of brass or plastic card that will slide easily into the coupler pocket but which is narrow enough to allow side-swing. A small hole can be drilled through the pocket and strip, and a short length of wire pressed in as pivot, having slightly enlarged the hole in the strip to ensure free movement from side to side. The Peco head is fixed to the strip as before.

 

Even this still results in a coupler / pivot arrangement that is visually too bulky, the problem being the relatively low level of the NEM pocket.

 

So - from now on it's back to basics, and I will be removing the NEM mount by unscrewing it or cutting it off. The Peco coupling will then be mounted below the headstock with the plastic pivot peg supplied by Peco, and a couple of short lengths of wire will be pressed into holes in the floor to limit the coupler swing.

 

.... in other words, what I did for years before the NEM coupler mounts were introduced !!

 

Regards,

John Isherwood.

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I've found any sort of lateral springing causes problems with couplings, unless it's very light, as in the Dublo R1* and N2. I'm not even sure it's necessary here, as the LWB wagons work perfectly without and the chassis dimensions are similar.

 

* Originally it appeared to be a piece of cycle valve rubber.

 

The classic case is the American X2f, where, as supplied, the spring is usually far too strong and causes the wheels to bind against the rails leading to derailments. It worked with the original Airfix kits (a rubber band was supplied for the spring!) but unfortunately their version will not couple with anything else*. They were cheap enough however at 2/- for 24 couplings.

 

* Cutting the 'horn' off enables coupling with the Peco type, but then they no longer reliably couple to each other.

Edited by Il Grifone
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  • RMweb Gold

The later development incorporates delayed uncoupling (it works similarly to Kadees but has a one piece 'knuckle'). Unfortunately it won't couple automatically with Dublo couplings. though it works with Peco's early version. (The problem is with the actual size of the knuckle.)  http://www.peco-uk.com/product.asp?strParents=3309,3322&CAT_ID=3325&P_ID=17335

 

I can see problems with trying to make a NEM compatible version, which is probably why they dropped the idea.

The NEM-mount heads made by Kadee (#17/18/19/20) incorporate a (very) lightly sprung pivot behind the head and they generally work very well.

 

The equivalent Bachmann EZ-Mate coupler head doesn't have this feature and success of use seems to vary with vehicle length/weight.

 

Peco could use a similar centering arrangement to Kadee but I think they would have to incorporate the dovetail in the coupler rather than using the normal pocket in order to make it short enough. That would make such a coupler conform to the NEM 363 standard (like Vi-Trains) rather than NEM 362. 

 

With or without a pocket, they would (like Kadee and, ironically, Bachmann) come up against the dreaded non-compliance with the NEM Standard for height that has blighted the adoption of this convenient feature ever since it arrived on the UK r-t-r scene.

 

John

Edited by Dunsignalling
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I've just discovered that the otherwise useless pillars that mount the GBL locomotives on the plinth can be used to mount HD couplings. The smaller diameter is just right for the couplings (and Jouef/Playcraft- Peco* may need reaming out slightly, as they do with Airfix coupling pins). The pillar can be cut to length** and the GBL screw can then be used to fix it to the vehicle or it can be glued, as the part is polystyrene. Then just add a couple of stops from wire or scrap plastic. (Don't copy the Airfix kits, as the stops on the headstocks are in the wrong place. Too much play for Peco (and too high for tension locks).

 

* I didn't have a spare one to hand to try. (Mislaid my box of them!  :scratchhead: :senile: )

 

** The rectangular part and the length of smaller diameter tube is the same as the boss on an Airfix Kit (mineral wagon and probably the others). some washers and packing will make fixing easy.

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  • 5 years later...
1 hour ago, 97xx said:

In the last 6 years, has anyone come up with a more successful solution to the challenge of fitting HD couplings to NEM-equipped RTR stock?

 

In short - yes.

 

My standard fitting is made from 2.5 (or 2.0) x 1.5mm. brass bar; the latter allows more side to side pivotting of the coupling.

 

The brass bar is bent and hammered in the vice to a sharp-cornered L; the shorter leg should be a minimum of 2.0mm. measured on the INSIDE of the bend. The longer leg will be cut to length later.

 

Trim the short leg to 1.5 - 2.0mm. and square off the end with a file. The exact measurement depends on the vertical location of the NEM pocket - you will learn in time what length a particular vehicle needs.

 

Take a Peco R2 coupler and cut off the shank and pivot, immediately behind the vertical tail.

 

File off the blackening of the underside of the coupler head, immediately behind the angled 'push bar'.

 

Tin the cleaned underside of the coupler head and the short end of the brass L, and solder them together so that the brass L forms a 'cranked downwards' stem to the coupler head.

 

Drill a 0.5mm. dia. hole in the exact centre of the NEM pocket that normally accommodates the 'fishtail' of a tension-lock coupler, passing through both faces of the pocket.

 

Offer the modified coupler up below the NEM coupler pocket, and mark and cut off the long leg of the L in line with the inner end of the pocket. The 'push bar' of the coupler should be roughly in line with the buffer faces.

 

Blacken the new coupler stem with a permanent marker, and place the stem in the NEM pocket such that the 'push bar' lines up with the buffer faces.

 

Turn a 0.5mm. drill into the hole already drilled in the NEM pocket a couple of times, so as to make a mark in the new blackening. Remove the coupler and drill the stem, at the mark that you have made, with a 0.7mm. drill.

 

Place the stem back in the pocket and press a length of 0.5mm. brass wire through the holes in the pocket and stem to form a pivot. Bend the wire at right angles on what will be the the underside of the pocket and cut off the surplus, leaving a short stub that can be gripped to pull out the pivot at any time in the future. The springy nature of the nylon pocket will retain the wire pivot by friction alone.

 

872432614_FITTINGTOWAGONSFORPECOR2COUPLINGS.JPG.b5a27059056f36d6a9ec18c20df11f05.JPG

 

I know - WHAT A PALAVER !!

 

But, when you've done a couple, it becomes second nature and you can churn 'em out by the dozen. In the time that it's taken to type this I could easily have produced a dozen, NEM-compatible Peco couplers.

 

John Isherwood.

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Splendid John, thank you.
 

Am I correct that you have them set for pretty close coupling?
 

I ask as I modified a B set and decided to close-couple the pair using the Peco couplings, at what would appear to be around the setting you suggest, but it does need adjusting as I get buffer lock over reverse 3’ radius points.

 

Obviously retaining more of the shank and soldering the upstand of the L to that would generate more length - which would work OK?

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Unfortunately, like most/all automatic couplings, the buffers get in the way and require an overscale spacing. Dublo solved this with dumpy little buffers and the on the real thing a removal collar allows them to be pushed back out of the way. (IIRC Peco recommended 1/8" in front of the buffers for scale and 3/16" for sharp curves - I'll dig out the instructions and check).

In the case of a B set, since they were permanently coupled, I copy the prototype and use a bar (read 'piece of wire') to couple; one end flexibly fixed to the coach body (or bogie if necessary) and the fits in a hole to allow the coaches to be separated. It works with DMUs and EMUs too.

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Yes, I would have used a bar but eed to be able to box them at the moment. Might make up something along the lines of a doubel-ended fishtail NEM design which can clip in and out of the Airfix coupling slot.

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Finding the instructions was harder than I thought. With all the later ones, you are on your own and I had to dig down to the bottom of my box of couplings to find one marked, "PRICE INC. TAX 2/4" with the 4 cancelled. (I can't remember them ever being that cheap! I have 2/6d fixed in my mind and 1/6d for just the hooks - nearly as much as the Airfix wagon kits). It was held together with clear adhesive tape which, unlike the current product, was still firmly fixed after all these years.

 

Waffle aside, it states, "Allow the tip of the coupling to protrude 1/8" beyond the head of the buffers or 3/16" when using sharp curves. omis the bottom of the de-coupling leg should be 1/32" above the top of the rail. It waffles on and then, "NOTE: When used with TRIX and ROVEX the de-coupling arm* should be bent inwards for approximately 3/32".

To ensure successful operation the coupling must move freely but without undue slackness. The coupling hook and swivel point should be oiled lightly with fine sweet oil. (I thought "fine sweet oil" had other uses, but we won't go into that!)

 

* Even Peco couldn't be sure what to call it, so I'll stick with Kadee's 'Coupler pin', translated into English. (The Peco label calls it a coupler on the front and coupling on the back!)

 

There are several versions of the beast with the most marked difference being a curved or straight striker which also varies in length. Curved strikers seem to work better -  Dublo ones are usually curved.

Edited by Il Grifone
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5 minutes ago, 97xx said:

Yes, I would have used a bar but eed to be able to box them at the moment. Might make up something along the lines of a doubel-ended fishtail NEM design which can clip in and out of the Airfix coupling slot.

 

The wire bar should be able to fold down out of the way to fit in the box or how about small magnets?

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5 hours ago, 97xx said:

Splendid John, thank you.
 

Am I correct that you have them set for pretty close coupling?
 

I ask as I modified a B set and decided to close-couple the pair using the Peco couplings, at what would appear to be around the setting you suggest, but it does need adjusting as I get buffer lock over reverse 3’ radius points.

 

Obviously retaining more of the shank and soldering the upstand of the L to that would generate more length - which would work OK?

 

B-set - remove the buffers; didn't most B-sets lack conventional buffers? (Any GWR coach experts out there)?

 

My setting allows buffers to nearly touch on Peco Medium Radius points. If you need longer couplings, just leave the new brass shanks longer when marking the pivot hole position. Leaving more of the steel shank may cause problems with pivotting and / or clash with vac. pipes, etc.

 

John Isherwood.

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6 hours ago, cctransuk said:

 

B-set - remove the buffers; didn't most B-sets lack conventional buffers? (Any GWR coach experts out there)?

 

My setting allows buffers to nearly touch on Peco Medium Radius points. If you need longer couplings, just leave the new brass shanks longer when marking the pivot hole position. Leaving more of the steel shank may cause problems with pivotting and / or clash with vac. pipes, etc.

 

John Isherwood.


yes that may well be the answer as many were buffer-less.  I did remove the set end buffers and put a straight beam Plus correct pattern buffers on as per original, but left the less visible intra-set ones as standard.

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The GWR never could make up its mind as regards B set-inner buffers. The type modelled by Airfix had a special short buffer. I leave the Airfix ones on the grounds you can't see them in the narrow gap between the coaches and leave the curved headstock as well (lazy I know, but life's too short...). The outer ends get straight headstocks and proper buffers.

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  • 5 months later...

Just embarked on converting some recent purchases - a Dapol Class 22 and a Bachmann Autocoach, both of which have NEM pockets.

 

What I discovered was that a cranked HD coupling fits perfectly into each/either and is automatically at exactly the correct height.

 

All that is needed is to cut the boss end off and square the end before sliding into the pocket.

 

The only minor fettle is to file/cut a small groove in the top front edge of the NEM pocket as the upwards crank has a small strengthening rib and unless you create a corresponding slot the coupling will be bent downwards as you slide it right in.

 

There is scope to adjust angle and height by a small amount if needed as the HD coupling thickness is less than the slot in the pocket.

 

 A drop of superglue then fixes.

 

EDIT: tested them on an Autocoach coupled to the Class 22 (!) and all works fine through reverse points. Checked against a 'reference' Dublo vehicle and again excellent.

 

I would expect a few situations where they won't couple easily as the 'spring' in the pockets might not be ideal or enough, but very pleased with a workable and easy solution.

 

IMG_7521.jpeg

IMG_7522.jpeg

IMG_7525D.jpeg

Edited by 97xx
Added report back on test
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