Tight radius couplings

[Schooner]

Afternoon all

 

I'm in the early stages of planning a layout set in the London Docklands c.1880 (small indutrial tanks engines shunting cuts of short wagons about, to a backdrop of warehousing and shipping. Topic here).

 

Approaching the point where I'm happy with the fundamentals, I now need to reality-check. The main issue I see is radius: although mostly >438mm, the plan hinges on two quayside curves of radius 350mm and there are Settrack points (ST-240/1). I'm fairly confident the stock I have in mind will cope with this okay...but will their couplings?

 

With the layout larger than a typical 'shunting puzzle' type, I'm keen to expore automatic uncoupling options. These seem to be:

• Tension lock - Pros: ubiquitous, radius friendly. Cons: obtrusive (especially on such small locos and wagons), as are the uncoupling ramps
• Kadee - Pros: reliable, plenty of variety. Cons: would look all kinds of wrong
• Magnetic '3-link' - I've seen a few home-brew versions, and I think Hunt have some on the way too. Pros: better aesthetics, ease of use. Cons: Automatic uncoupling would have to come via physical chocking of the target wagon...?
• Spratt and Winkle - Pros: proven, not bad looking. Cons: minimum radius requirements
• Dingham - as above
• AJ couplings - reputation for poor reliability (use of construction jigs would seem to eliminate this), but near-invisible; uncertain of other tolerances.

 

What have I missed? What would you go for?

 

Thanks for your time,

 

Schooner

 

 

 

[The Johnster]

350mm minimum radius equates to setrack radius 1, which will preclude absolutly the use of any couplings except tension lock, Kaydees, and Hornby Dublo/Peco ('buckeye').  I am unfamiliar with Kaydees in use and cannot comment on thier suitability as there will, I'm sure, be replies from people better qualifed than me.  The feature common to all 3 types is that they act as buffers as well as couplings, holding the wagons far enough apart to prevent buffer locking.  This means that scale distances between wagons and buffer heads are compromised, but you have to accept this if you are to use radius 1 curvature.  'Scale' couplings which do not hold the wagons apart need a minimum of 30" radius, Peco Streamline medium (sorry, I'm a metric-averse Luddite, this would be 762mm radius, I'll try to use metric from here on in), but I have in the past gotten away with 609.6mm, Streamline small radius by the cheat of mounting the drawhooks 1mm further 'proud' of the buffer beams and fitting very lightly sprung buffers.

 

I would go for tension locks, specifically Bachmann NEM.  Tension lock couplings are only as compatible between types as the producers claim whin hauling stock; propelling is a whole different bucket of potato peelings.  Hook and bar profiles, material, counterweights, mounting methods, and height above the railhead (this is vital for reliable propelling of stock) all differ.  Bachmann come complete with the NEM box and the fishtail fitting, in 2 lengths and straight or stepped down versions.  Where kit or other producers' wagons need to be fitted with them and there is no fishtail mount, cut whatever mount there is away and use Parkside NEM coupling mounts, avaialble in packs of 12.  These are soft plastic and can be easily trimmed if necessary to achieve the correct bar height above the rail head.  Some coupling droppers may, I have found, have to be trimmed slightly to clear crossing rails at turnoutss.

 

The combination of the lateral play in the coupling hook and that imparted by the 'waggler' of the NEM pocket should be sufficient for your minimum curves.  You may find it advantageous to ballast all wagons and vans to a standard weight. 25 grams is often quoted, which will prevent heavy vehicles' coupling bars overriding lighter ones' and derailing them.  I have used overriders in the form of wire rod superglued perpendicular to the bar in extreme cases of this.

 

Tension lock couplings couple automatically, and there is sadly no way that they can be made not to for loose shunting other than the Dingham modification; again. Bachmann's are advised for this being of all plastic and hence non-magnetic construction.  They can be uncoupled with ramps, which I find obtrusive, or with a hook or spade.  A hook, mine is made from stiff wire superglued to a piece of old rail bent to a suitable shape, iteself strapped to a poundshop led worklight, is used from above or to the side and lifts both coupling hooks clear of the bar; you then move one wagon away slightly and drop the hooks.  A spade work in the same way, but by pushing up the droppers from beneath, basiaclly a portable hand held uncoupling ramp, thus clear side access is needed, which means that the system cannot be used in my bay platforms. 

 

Another advantage to t/ls is that RTR locos and stock already have them when they come out of the box!

[Wheatley]

3 links will work on 1st radius curves (15") but only on short wheelbase wagons and locos with absolutely no overhang and with short buffers i.e. a short 0-4-0 and 16t minerals or similar. You may have to adjust the length of links on wagons with longer buffers (eg Oleos).  Propelling could only be carried out at dead slow. It's do-able but only just and with a lot of restrictions. 

 

AJs are unreliable in OO, there is too much lateral slop between wheel and rail. 

[Il Grifone]

The lateral slop in 00 also rules out 3 links in my experience. I changed to EM to avoid this. Sharp curves mean sprung couplings and/or buffers as well. (Ruling out the 'Queen Mary' anchor chain type once prevalent!)

Sharp curves suggest one of the proprietary coupling intended for such things - basically the Dublo/Peco Simplex, tension locks or the Continental loop type. (Kadee might work, but are recommended for 18" and above. All of these render buffers redundant and either need to keep the vehicles too far apart (or adopt Dublo's dumpy version).

My preference would be the HD/Peco, but it does need careful adjustment as to height and ensuring the knuckle is vertical.

[ejstubbs]

23 hours ago, The Johnster said:

30" radius, Peco Streamline medium (sorry, I'm a metric-averse Luddite, this would be 762mm radius

 

If you're referring to the radius of the turnouts, Peco quote the (nominal) radius of the code 100 and code 75 medium radius turnouts as 914mm (36").  The small radius turnouts are quoted as having a nominal radius of 610mm (24").

 

23 hours ago, The Johnster said:

Bachmann's are advised for this being of all plastic and hence non-magnetic construction

 

They are non-magnetic, but unlike the rest of the coupling, the hook is not plastic.  You can scrape or sand the black coating off to reveal the shiny metal underneath:

 

 

This might be useful if you wanted to adopt the Brian Kirby automatic uncoupling method (Google for details) as, depending what the metal actually is, you might be able to solder the necessary ferromagnetic wire 'legs' on to the Bachmann hooks rather than gluing them.  I've not tried this, though, so it may turn out to be unworkable.

 

(ISTR reading about a modification of the Brian Kirby method that gives delayed uncoupling, but I can't remember where I saw it.)

[Schooner]

Thank you for the responses, that's all very helpful. Sorry it's taken so long to acknowledge them.

 

@The Johnster - not to worry, I bounce between metric and imperial with alarming freedom and am happy receiving advice in both! Tension locks do seem the way to go, although they'll stick out like things on a wotsit on the kit-built short wheelbase dumb-buffered mid-19th C stock the layout requires...but better they look bad an work reliably than the other way round.

 

@Wheatley Thanks for your thoughts on 3-links, and interesting to hear there may be options in this direction. Sadly some uncoupling positions would require an uncomfortable reach, and automatic options are I think the only realistic way to go. I did wonder about the 'magnetic 3-links', where the aesthetics are close to the real thing but the mechanism is purely magnetic rather than physical...sounds like it's still worth exploring, thank you. @Il Grifone likewise, for your clarifications.

 

@ejstubbs I think you might have found the sweet spot in suggesting the Kirby alterations to Bachmann tension-locks. Not the set of compromises I'd ideally want, but perhaps the right thing for reliable shunting. And without that, the whole thing rather opens up and all the fun falls out.

 

Thanks again, all the best,

 

Schooner

[The Johnster]

Things on a wotsit, like it!  They will, but there are measures that will lessen the effect a little and it’s surprising how one’s perception of the scene ‘tunes them out’ and one becomes effectively unaware of them most of the time.  Painting them a general dull matt grey/brown camouflage helps. 
 

I find that inaccuracies or visual anomalies that draw attention to themselves far more disturbing, such as vehicles sitting too high or low, or not level.  A roof ventilator out of line by a fraction has the ability to drive me nuts (mind, there are those that reckon I’m more than half way there already), and I cannot run a Fruit C made from the body of a Dapol Fruit D with my Parkside Fruit D because they are different widths (Parkside is correct but the Dapol tooling, inherited from Hornby Dublo via Wrenn, is a scale 9” too wide; cutting it down to Fruit C length worsens this in a proportional sense but I’m happy with the van so long as the Parky D is not there to illuminate the problem). 
 

My perception of these issues is inconsistent; the failed alignment of wheels and splashers on a ‘Limbach’ 94xx is more of an issue to my mind than the completely inaccurate axle spacing and position of the splashers on a Hornby 2721, because the 2721’s wrongly positioned splashers line up correctly with it’s wrongly positioned wheels on their wrongly spaced axles.  Tension locks sticking out like things on a wotsit are not my biggest problem... 

 

 

[Sol]

for episode 1 of auto 3 link couplings then type in  Great Chesterford junction episode 106