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More notes on Using Kadee couplers on British stock

I am indebted to Peter Barton for providing me his notes and experiences on converting to kadee couplers.

Here are some basics that I wish someone had explained to me when I first started.

Firstly decide whether you are a collector or an operator. You can often do the conversion in a way that's reversible if you want to restore the vehicle to its original condition but it's usually more difficult and often does not look as good. Unless you are likely to want to sell the model in the future I would say remove the original coupling and all its mountings etc.

Coupling types:
The 30 and 40 series are all you are likely to need plus, possibly the 16's etc - see below. The 30 series have plastic shanks and the 40 series are metal but the shanks are otherwise interchangeable. Each series has 9 different sub-types, three knuckle heights for each of three shaft lengths. The 30's have more compact draft boxes which you may need in some situations but where possible go for the 40 series because they are cheaper. A number 5 (#5) is what would otherwise be a #46 i.e. medium length, medium offset knuckle so use #5's wherever possible as they are the cheapest of all and can often be bought in bulk packs which are cheaper still.
I suggest you start with a bulk pack of #5's (shank and draft box complete) and maybe one packet each of the other 40's. You could also invest in a packet of No 30 draft boxes and springs. This will give you at least four of every combination so you can try them out. The 16, 17, 18, 19 couplers are for European NEM coupling pockets fitted to some Bachmann models. They are simple to fit (just drop out the old and in with the Kadee) BUT there are height problems with some Bachmann and I find the new couplers tend to drop out (although no-one else seems to have this problem). The 16's etc are very expensive compared with the 30's and 40's and unless you want to be able to restore the original coupling, I would use a #5 instead. (You may want to cut away the NEM pocket to get a snugger fit.)

From Kadee, I recommend a height gauge (virtually indispensable) and a pair of trip pin pliers (useful but not essential). Other useful tools are:
  Needle point tweezers or pliers
  A good heavy craft knife
  A mini drill with cutter and rotary file attachments
  Needle file(s) for finishing and fine adjustment
  Jewellers (or small) screwdrivers
  A length of test track with the height gauge fitted
  Kadee uncoupling magnet(s) - for test purposes
Other materials:
  Kadee Grease-em (Graphite lubricant)
  Kadee screws and drill tap -
 - not needed if you glue the couplings in place
  Plastic solvent
  Kadee washers and shims or -
 - Plasticard in various thicknesses
  A selection of plastic microstrip
The last two are for building up you own shims and mounting platforms.

Mounting position - bogies (truck) or underframe:
With fixed wheelbase wagons you obviously have no choice and these are generally very easy. With most modern stock the Kadee #5 simply fixes to the bottom of the wagon floor - use shims if necessary but not usually needed. I cut off the original tension coupler mounting posts but of course that is a one way process. On tender locomotives I do not usually fit an automatic coupling to the front (I'm a follower of Patrick Stirling who forbade double-heading) and the tender wheelbase is usually short enough that you can get away with body mounting. Similarly with tank engines, the short wheelbase normally allows body mounting front and rear (unless you have Very sharp curves).
Coaches are a different matter and it is governed by your minimum radius. If my layout had a 3ft minimum, I would probably use underframe mounting; it's easier and more prototypical. However, I have some radii as low as 2ft and you need to leave such a gap between vehicles it looks awful. The overhang also makes coupling on anything approaching a curve impossible. I therefore use bogie mounting which is usually more work but also more practical. I recently explained the method of dealing with Hornby bogies on the LNER Group. A final point on this; if you have say 2ft curves and you choose to mount the coupling on the underframe, the bogies may also need surgery to allow the bogie frames to clear the Kadee draft box on bends.

Mounting position - lateral:
This is very subjective. Again assuming 2 ft curves, if you use the standard #5 and unless you have very effective sprung buffers, you will need to position the coupling far enough forward that the front of the draft box protrudes from the underframe. You can get around this using long shank couplers but this adds to the expense - a matter of realism and taste. If you are using bogie mounting, I guess it does not matter as this is un-prototypical anyway. MOST important! Check your vehicles' running in push as well as pull mode - there is a surprising difference. The coupling needs to keep the vehicles far enough apart that the buffers do not lock on the sharpest curve round which they will be PROPELLED. Much closer coupling is possible round bends where they will be hauled.

It is the knuckle height that's important. If it's easier to mount the draft box higher or lower then do so; you can always compensate to some extent by using an underset or overset shank. You can also use a No 30 draft box in tight situations. So don't be dismayed if at first sight it seems impossible to fit a Kadee. That is why I suggested earlier that you equip yourself with the full range of available coupling types.

All the text in this article is copyright Peter Barton and may not be reproduced without permission.

For the latest info on Kadee couplers with useful drawings and descriptions of most couplers try

This page last updated on
8 April, 2014


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