Hornby/Airfix 12t Van Chassis

[nathan70000]

Hi

 

I recently acquired some Dapol BR 12t vent vans, I know they're not as good as the Bachmann ones but they were very cheap and "fit" better with the rest of my rolling stock which is mostly Hornby.

 

The couplers Dapol use aren't very good, frankly, and are rather droopy. I had a spare ex-Hornby Railroad van chassis that was a relatively smooth replacement and enabled me to fit my preferred coupling, but I can't seem to find any more. Does anyone know the part number? AFAIK these vans are still in production so spares should be available.

 

Thanks

[The Johnster]

If they have NEM couplers, that is, ones that fit in a sort of dovetail plastic mount and can be removed by pulling them downwards though I recommend prising them down with an old screwdriver or something as they can be a bit delicate, then it's a very simple matter of pulling the old ones out and buying a bag of new ones.  They come in permutations of long, short, cranked, straight, and offset; for wagons or vans you need short straight ones; I think you get a dozen in a pack.

 

But I'm not certain that all Dapol wagons are fitted with these; the company is still knocking out some that were inherited from Wrenn and even Hornby Dublo, which have rather crude chassis (by current standards) with plastic wheels (ugh, spread crud all over the place) and moulded on handbrake levers.  By the time you've sorted the wheels and the couplers it may not have been much of a saving over the Hornby or Bachmann equivalent!

 

If they're not NEM, as some Hornby Railroad items aren't for instance, then you may have trouble mounting replacement couplings as there was no standard mount prior to NEM.  Tension lock couplers were produced to a nominal standard, but the actual bar and hook sizes and profiles were quite different and sometimes made a mockery of the idea that all t/l couplers are compatible.  You should get away with it so long as all the bars are the same height above the rail head, but the different bar profiles can mean that they override each other when propelling.  

[Robin Verth]

Both the Hornby and Dapol wagon chassis for Vans originated with Airfix and until a few years ago was identical Dapol modified theirs to NEM sockets I use Hornby or Bachmann couplings rather than Dapol ones as they do not seem go droop I have been using Dapol chassis to replace Wrenn & Hornby Dublo ones.

For the ex Triang wagons the Bachmann China clay wagon chassis is the right length.

[davetheroad]

I have a lot of Dapol wagons and agree about the floppy couplings being a problem, the hooks can also fall out at awkward moments. The original tension lock had rigid bars, any flexibility needed came from the hook so I tried some mods on a Dapol wagon.

 

I first made a height above rail gauge, I think the top of the coupler bar should be 8.5mm above rail top plus or minus 0.2mm. I then glued a 5mm spacer between the top of the coupling box and the chassis. This gives a bar height of almost 8.5mm and removed all the vertical flop. There is still a little side to side movement but that can be cured with a little rubber cement. To cure the loose coupling hooks I glued and trimmed  a short length of 4x1mm Evergreen strip to the top of the coupling so the hook still moves freely but can't pop out.

 

After so many decades why have manufacturers failed to adopt standards for the profiles of the coupler bar and hook?

 

5mm spacer between top of coupler box and chassis plus 4x1mm strip added to top of coupler flush with box

 

the finished job

[nathan70000]

Many of other wagons are either Hornby, Airfix or early Dapol and they use the Airfix method of coupling fitting. To a degree I think this a superior method to NEM as it seems to keep the coupler more secure.

[davetheroad]

Have a look at the Bachmann Mini Long coupler 36-026

[wasdavetheroad]

On ‎1‎/‎27‎/‎2019 at 1:11 PM, davetheroad said:

I have a lot of Dapol wagons and agree about the floppy couplings being a problem, the hooks can also fall out at awkward moments. The original tension lock had rigid bars, any flexibility needed came from the hook so I tried some mods on a Dapol wagon.

 

 

 

 

I first made a height above rail gauge, I think the top of the coupler bar should be 8.5mm above rail top plus or minus 0.2mm. I then glued a 5mm spacer between the top of the coupling box and the chassis. This gives a bar height of almost 8.5mm and removed all the vertical flop. There is still a little side to side movement but that can be cured with a little rubber cement. To cure the loose coupling hooks I glued and trimmed  a short length of 4x1mm Evergreen strip to the top of the coupling so the hook still moves freely but can't pop out.

 

 

 

 

 

After so many decades why have manufacturers failed to adopt standards for the profiles of the coupler bar and hook?

 

 

 

 

 

5mm spacer between top of coupler box and chassis plus 4x1mm strip added to top of coupler flush with box

 

 

 

 

 

 

 

the finished job

 

 

 

Oops, that should be a 3mm spacer between the chassis and the top of the NEM coupler box. Actually nearer 2.8mm

Edited February 3, 2019 by wasdavetheroad

[34theletterbetweenB&D]

On ‎1‎/‎27‎/‎2019 at 1:11 PM, davetheroad said:

...After so many decades why have manufacturers failed to adopt standards for the profiles of the coupler bar and hook?...

 

Because despite a couple of good attempts there is no national body recognised by the RTR producers as a standards  setting organisation. Instead our 'standards' are a mixture of borrowings from the NMRA and NEM organisations plus some established custom and practise.

 

The tension lock in its presently retailed forms is effectively unique to OO, so neither of the NMRA or NEM have anything to say about it, and apart from height of the bar above rail, the only specification is 'is a tension lock in form'.

 

You have to create your own standard. Mine became 'exclusively Bachmann miniature tension lock' because for all this type of coupler's  limitations they can be used to produce a good loose coupled freight effect, and Bachmann had succeeded in selling me hundreds of such loose coupled wagons, due to their really useful subject choices!

 

But this is not a real standard. Bachmann could decide at any time to alter the design, and then IWBUSCWAP (jiggered).

[The Johnster]

Exactly, 34.  Tension lock couplings have been in existence AFAIK since Lines Bros (Triang) absorbed Rovex, about the mid 50s, but there have been very many different types of the them, all of which are claimed to be compatible with each other.  In the sense that they all have a vertically pivoted hook which fits over a horizontal bar, they are, but not in any other sense.  

 

As well as the lack of an enforceable common standard, there is the other problem; that they need to be mounted in different types of positions, ranging from the wagon floor behind and below the buffer beam of 4 wheeled wagons to coach or multiple unit bogies, loco leading or trailing ponies or bogies, t0 diesel or electric locos with 'problem' fronts like Westerns or Class 40/Peak.  So to be fair to the manufacturers, achieving a standard that will work in every situation is not as easy as it looks, especially when the model has to be negotiate such insanely under scale curves as we mostly ask ours to do.

 

NEM is not a coupling standard, but a mount standard, a 'plug in' sleeve for the actual coupling and a dovetail mount to secure this to the vehicle where one can be employed.  At least this has enforced a generalised similarity to the situation, but we still have several variations of hook profile, bar profile, and length, as well as a choice between straight and cranked.  The height of the bar above the railhead is probably the most important dimension for reliable operation, and must be standard throughout a layout's stock even if it is incorrect (!), but in practice there is a bit of a grey area here and anyway the coupling may drop out of it's dovetail.  If the bars are so out of line that they override each other, there is a good chance of buffer locking or derailment if a heavier wagon is bearing down on the bar of a lighter one.

 

Another issue is the dropper, necessary to give weight to the hook and facilitate the operation of automatic uncoupling.  There is no standardisation of the shape, 'depth' or profile of this, nor of a distance from the hook pivot or the dovetail mount.  This can lead to fouling on turnout rails or similar obstacles, and I have had to trim several of mine.  It has an effect on uncoupling if you use ramps or a 'spade' to lift the hooks by these droppers; I have found that a spade wide enough to cope with all the variations of dropper position cannot be used between all vehicles.  

 

As a result, I have given up on the spade method and use a hooked wire 'shunting pole' attached to a small flashlight; this works in all situations I have so far encountered, but might be challenged by setrack curvature and will be very awkward if you have to uncouple stock with gangways; my BLT only has one or two of these in the form of NPCCS.

 

It's not all bad news.  NEMs are easily obtainable, the dovetail mounts are supplied by Parkside to convert older stock, and once you've established the best standard you can across your layout, the couplings are pretty much 100% reliable.  The devil's in the detail, and concealed in the words 'once you've established', though!

 

My coal trains are composed entirely of Bachmann or Oxford minerals with NEM couplers and I am quite happy with the 'loose coupled' effect, especially with a slow start of the loaded train as the couplings stretch just a little as the strain is taken up...

Edited February 3, 2019 by The Johnster