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Problems with Hornby and Bachmann tension lock couplings


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I'm sure  that I am not the only one to experience this problem. I use the plug in  NEM type coupling on my models, both on rtr models and on my scratch or kit built S Scale models. On numerous occasions the coupling hook - metal on Hornby couplings and plastic on Bachmann couplings - comes away from  pivot point into which the hook clips. It's almost impossible to get the hook back in satisfactorily and often comes away again.

 

Has anybody found a solution to this issue?

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It's a darned nuisance! I keep a stock of spare plug-in couplings and immediately replace the ones that fall apart like this. It is possible to replace the metal hook on its pivot and then gently squeeze the two arms slightly closer around the pivot bar. My success rate is only about 50%, though. If it reaches desperation point, I can put up with only one of a pair of touching couplings having the metal hook on it.

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You are most certainly not the only one to experience this problem, to which I have not found a solution, though I will sometime later today have a go at Mike's repair method.  My method of dealing with it is otherwise the same as Mike's, a stock of spare couplings to replace any hookless ones that occur. 

 

My mineral trains, one loaded one empty, are permanently coupled rakes with tension locks only on the outer ends; within the rake I use James' Trains 3D printed 3-link or instanters as appropriate.  These are avaialble from Shapeways and consist of the complete coupling, with hooks and the other coupling hanging down, detailed to include the 'horns' on the instanters that are used to shorten or lengthen the coupling with a shunting pole, and the NEM standard fitting on each end to go into the pockets.  I have found these to be very reliable but the empties rake needs a bit of ballasting for the sharpest curves.  No connection happy customer.

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Apart from the hook separating from the loop,  another issue with the Hornby coupler hook is that the hook remains in the unlocked (raised) position,  requiring manual intervention to return it to the locked (engaged) position.  For years I never had a functionality issue with the typical large tension lock coupler.  Also never had an issue with the early release Airfix small coupler.  The small Hornby tension lock coupler (NEM) though and the small coupler based on the old Airfix design are a problem.

Edited by GWR-fan
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Dapol couplers are even worse for escaping coupling hooks. I used tiny dots of superglue to fix a small piece of thin black card over the hook hinge. It worked. 

 

I have also met the occasional Hornby hook that won't return to the down position, carefully remove the hook and check the hinge end has no burrs, also the socket might be slightly obstructed. I still have some awkward hooks though and intend to add weight to the drop bar to persuade them to drop.

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My cure for errant Bachmann or Hornby metal coupling hooks is to press them back onto the pivot.  If they subsequently fall off again, a judicious nip with a pair of pliers closes up the gap in the hook enough to keep it on whilst still allowing the requisite movement.  

 

There's a bit of a knack to doing it, and it only needs to be closed up by half the width of a flea's thing*, but it works for me :)

 

*half the width of a flea's thing being less than the thickness of a tadpole's todger.

Edited by spikey
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I've just done a few Hornby couplings -these have metal hooks. I turned the model upside down and let the coupling drop so that is vertical. Then using a pair of tweezers (or a very small pair of pliers) give a very, very gently squeeze to compress the metal part by putting one of the jaws under the plastic and the other on top of the metal loop. If you compress it to much it will stop the loop falling back under gravity. Not easy but possible.

Edited by steverabone
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1 hour ago, Allan Condie said:

I have problems with these pesky units self uncoupling.  There is no reason for them doing so.   Any suggestions?

Fit Kadees.   The old all metal loop TRiang tension locks stayed coupled and you could adjust their height although by and large they didn't need adjustment.  The TT version has my vote as the best tension lock coupling ever.

The more modern Chinese plastic ones suffer poor quality control, poor materials and poor design  and often droop in their mountings or are at inconsistent heights.  The  Drooping  uncoupling am fouls point blades and causes derailments and uncoupling.  The only ""Cure" is careful setting up so the tops of all the loops are at precisely the same height, even then reversing is a lottery.   I use Peco couplings to avoid these issues except in fixed rakes where I use carefully adjusted and close coupled tension locks. Mainline 1980s for preference.

I have started gettingbrid of NEM Pockets, they are very ugly as  prototype wagons have  nothing at all where the NEM blob lives, and a rough start with a long train and the coupling pops out of the pocket.

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The problem with tension locks is usually that they won't uncouple - i think of them as tangle-locks for this reason. It is essential that they are all at the same height above the rails for sucessful operation, Knuckle couplings will allow a small vertical tolerance as long as the actual knuckle is vertical.

I agree that the Mainline type is superior and use these on the few items I have with tension locks. The Tri-ang TT and Peco 'Anita' are also OK but hard to find/expensive these days.

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1. I have been adjusting these hooks for a few years now. Closing up the loop to stop the hook pulling out or using a round file to open the hole so the hook drops back down.

 

2. Uncoupling usually happens because one coupling is higher than the other and not fully engaging in the opposite loop.

 

 

Dave.

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23 hours ago, DCB said:

The old all metal loop TRiang tension locks stayed coupled and you could adjust their height although by and large they didn't need adjustment. 

The more modern Chinese plastic ones suffer poor quality control, poor materials and poor design  and often droop in their mountings or are at inconsistent heights.  The  Drooping  uncoupling am fouls point blades and causes derailments and uncoupling.  The only ""Cure" is careful setting up so the tops of all the loops are at precisely the same height, even then reversing is a lottery.   I use Peco couplings to avoid these issues except in fixed rakes where I use carefully adjusted and close coupled tension locks. Mainline 1980s for preference.

I have started gettingbrid of NEM Pockets, they are very ugly as  prototype wagons have  nothing at all where the NEM blob lives, and a rough start with a long train and the coupling pops out of the pocket.

Triang Mk 3 coupling (X171) was not bad in its day, definitely an advance on the Mk2.  It tended to be difficult to fit to kits or anybody else's stock though, and yes its height was critical.  The main criticism was usually its sheer ugly and unprotitypical appearance though. 

I can only agree that so many of the plastic versions and smaller tension locks just won't couple on curves, the drooping ones are nightmare and heights are inconsistent.  Propelling is asking for trouble. 

Some couplings for NEM pockets seem to be better than others, though I haven't worked out which are best/worst, but some are badly designed and again there is drooping.  Some of them do pop out of the pocket (even if they're the last vehicle in the train).  Sometimes the coupling seems to be thinner than it should be to suit the pocket, but more often the fault is caused by insufficient spring on the prongs that are supposed to lock them into the socket - perhaps an inappropriate choice of plastic?  If you're happy with the coupling however, that particular problem be solved using glue, although making the fixing permanent does rather defeat the object of using a pocket.

 

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31 minutes ago, Michael Hodgson said:

Triang Mk 3 coupling (X171) was not bad in its day, definitely an advance on the Mk2.  It tended to be difficult to fit to kits or anybody else's stock though, and yes its height was critical.  The main criticism was usually its sheer ugly and unprotitypical appearance though. 

I can only agree that so many of the plastic versions and smaller tension locks just won't couple on curves, the drooping ones are nightmare and heights are inconsistent.  Propelling is asking for trouble. 

Some couplings for NEM pockets seem to be better than others, though I haven't worked out which are best/worst, but some are badly designed and again there is drooping.  Some of them do pop out of the pocket (even if they're the last vehicle in the train).  Sometimes the coupling seems to be thinner than it should be to suit the pocket, but more often the fault is caused by insufficient spring on the prongs that are supposed to lock them into the socket - perhaps an inappropriate choice of plastic?  If you're happy with the coupling however, that particular problem be solved using glue, although making the fixing permanent does rather defeat the object of using a pocket.

 

 

I often raise the couplings using a slither of 5 or 10thou plastic card under the coupling as i push it into a socket. I need mine dead correct as I use the Brian Kirby idea of magnetic uncoupling.

Only works with Bachmann couplings so I also replace most of them with their shortest version which also closes the gap.

 

Dave.

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40 minutes ago, Michael Hodgson said:

Triang Mk 3 coupling (X171) was not bad in its day, definitely an advance on the Mk2.  It tended to be difficult to fit to kits or anybody else's stock though, and yes its height was critical.  The main criticism was usually its sheer ugly and unprototypical appearance though. 

I can only agree that so many of the plastic versions and smaller tension locks just won't couple on curves, the drooping ones are nightmare and heights are inconsistent.  Propelling is asking for trouble. 

It was ugly, but the X171 incorporated a range of features that subsequent iterations have got rid of, all of which were elements that made it super-reliable. Firstly, it was pressed metal - this ensured much easier fine adjustment to the height, near 100% accuracy of the hook being free to raise and drop freely, and it also made it very straightforward for the hook to engage under the bar thus avoiding accidental uncoupling. Secondly that big rounded hoop acted as a model version of the buffers/rubbing plate, avoiding buffer locking and ensuring that hauling and propelling worked. The very act of making it a teeny-tiny plastic bodied coupling means that pretty much all of the design and physical properties of the original have been compromised. The only saving grace is that they can be removed and replaced or substituted much more easily. 

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I have found that on Heljan diesels an instant improvement can be made by fitting Bachmann straight (non-cranked) couplings, either short or long as required. I don't have many Dapol wagons but I solved the droopy couplings on one by removing the NEM pockets and using pliers to bend the socket upwards - slightly nerve-wracking but it's only a small adjustment and the plastic is quite tough.

 

I do wonder whether the common 'springing' arrangement which relies on the flexibility of the thin plastic at the 'hinge' point actually does anything in use - I'm thinking more about lighter 4-wheel wagons and coaches with couplings mounted on the bogies (e.g. Hornby Mark 1s) than heavy locomotives, especially the longer ones.  In other words, would the stock behave any differently - or better - if the couplings were rigid. The now rather ancient Bachmann china clay wagons still have screw-on small couplings, I'm not aware of complaints of derailing due to 'coupling lock' (these are 9' wheelbase but this would have only a marginal effect compared to 10').

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2 hours ago, Michael Hodgson said:

 

Some couplings for NEM pockets seem to be better than others, though I haven't worked out which are best/worst, but some are badly designed and again there is drooping.  Some of them do pop out of the pocket (even if they're the last vehicle in the train).    -----  If you're happy with the coupling however, that particular problem be solved using glue, although making the fixing permanent does rather defeat the object of using a pocket.

Some of our locos need to use Tension locks on friends layouts (and if sold on again) and Peco at home.  I have drilled the detachable NEM pocket vertically with the coupling in place and  counter sunk the Top of the socket and inserted a track pin from the top to hold the coupling in.  Cutting the track pin to length.  Gravity holds it and you can still change  the coupling. Talking pin vice and £1 pack of Chinese mini drills here not high tech.  Sometimes the couplings need shimming to take up the vertical play . I tend to work with thin brass or N/S  but drill the hole in the metal separately or the drill will skid off sideways and ruin everything

 Likewise on some of the worst coach NEM sockets where I kept tension locks between coaches I have done the same,  End of the set have Peco type.

Next Problem is Hornby Detachable NEM Pockets work their way out of the fitting.  
 

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On 02/07/2023 at 13:43, DCB said:

 

Next Problem is Hornby Detachable NEM Pockets work their way out of the fitting.  
 

If this is the problem I think you are on about..  try…

packing out the fishtail with a bit of paper,to tighten the fishtail up in the socket, trim after squeezing the coupling in the socket .

 

if only the hook’s were so simple

Edited by Graham456
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On 02/07/2023 at 10:35, Michael Hodgson said:

Some couplings for NEM pockets seem to be better than others, though I haven't worked out which are best/worst, but some are badly designed and again there is drooping. 

Since the miniature versions of the tension lock (MTL) re-emerged roughly 25 years ago, first from Bachmann, then Hornby, I set up a performance trial. Both were capable of reliable operation if correctly set up for consistent height, and not mixed. Used together, tangles; so since at the time Bachmann were making the wagons I needed, their's was standardised on my operation. 

 

I have not subsequently systematically trialled further brand's versions of MTL couplers, as I have insufficient examples for a valid result; though some of the announced Accurascale product may change this.

 

On 02/07/2023 at 11:10, dasatcopthorne said:

I often raise the couplings using a slither of 5 or 10thou plastic card under the coupling as i push it into a socket. I need mine dead correct as I use the Brian Kirby idea of magnetic uncoupling.

Only works with Bachmann couplings so I also replace most of them with their shortest version which also closes the gap.

Seconded, a happy asset of the Bachmann type having a non-ferrous metal hook. The magnetic uncoupling works efficiently, and if you happen to also use Kadee (as l do) is operated by Kadee magnetic uncouplers, permanent and electromagnet types. That's a happy bonus.

 

Further improvement by shortening the coupler pockets and coupler mount to place the bumper bar face in the same vertical plane as the buffer head faces yields a loose coupled effect on SWB wagons such that the buffer heads are in contact when propelled, but buffer locking is prevented, and open out to 2mm between buffer heads when pulled. Caveat requires a minimum radius of 24" .

 

What must be appreciated is that this is a commercial product to no recognised standard. Bachmann could alter it to make it backwards incompatible tomorrow.

 

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6 hours ago, 34theletterbetweenB&D said:

Since the miniature versions of the tension lock (MTL) re-emerged roughly 25 years ago, first from Bachmann, then Hornby, I set up a performance trial. Both were capable of reliable operation if correctly set up for consistent height, and not mixed. Used together, tangles; so since at the time Bachmann were making the wagons I needed, their's was standardised on my operation. 

 

I have not subsequently systematically trialled further brand's versions of MTL couplers, as I have insufficient examples for a valid result; though some of the announced Accurascale product may change this.

 

Seconded, a happy asset of the Bachmann type having a non-ferrous metal hook. The magnetic uncoupling works efficiently, and if you happen to also use Kadee (as l do) is operated by Kadee magnetic uncouplers, permanent and electromagnet types. That's a happy bonus.

 

Further improvement by shortening the coupler pockets and coupler mount to place the bumper bar face in the same vertical plane as the buffer head faces yields a loose coupled effect on SWB wagons such that the buffer heads are in contact when propelled, but buffer locking is prevented, and open out to 2mm between buffer heads when pulled. Caveat requires a minimum radius of 24" .

 

What must be appreciated is that this is a commercial product to no recognised standard. Bachmann could alter it to make it backwards incompatible tomorrow.

 

 

Surely there is a recognised standard. NEM!

 

Dave.

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3 hours ago, dasatcopthorne said:

Surely there is a recognised standard. NEM!

In this context that solely  defines coupling mountings and its positioning on vehicles.

 

The miniature tension lock coupler is not defined, other than by brand management's private  specifications. The evidence is readily available: Bachmann and Hornby MTL's are significantly different in dimensions and materials, (I haven't looked further, others may have done, and if so please comment.

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