True minimum radius for modern stock? (Couplings issue)

[john new]

Although related to modern coupling fittings this NEM/Kadee debate raises other issues (Not modern t/ls) hence this separate thread.

 

My question after trying, and failing, to get a set of three recently bought wagons to run through my shunting plank's reverse curves without derailing is what is the true minimum radius for modern r-t-r stock? Not the radius it will run through as a single vehicle but the radius it can go through hauled/ing and propelling if fitted with the modern style of titchy t/ls. (This post from 27 March in my layout thread has more).

 

I think the current track will have to be ripped up as I now have several recently bought locos that run OK light engine but can't haul/push a train with their existing titchy couplings. (Bachman Cl 20, Model Rail USA tank, Dapol B4 & Hornby Sentinel diesel). Add to that at least another eight freight vehicles with the same coupling issue. Replacing the track now is cheaper than re-equiping every new item of rolling stock!

 

The annoying thing is that all my older stock runs through everything just fine with their larger t/ls. I retro fitted one of my three new Bachman Whisky hoppers this morning with two old Hornby couplings it now works fine. Not so the other two I had a look at this morning, one size from my spares box was too short (buffer locked/derailed) the other long enough to avoid that issue but still too narrow in the loop to allow adequate hook swing. The related issue is the flimsy clip in hooks regularly fall off!

 

I how have well over £500 worth of stock advertised as able to run through 2nd radius curves, which it will if l/engine but not if coupled to anything as it derails the attached stock! The photo shows original and two sizes from my spares box, none suitable for running reliably through 2nd radius reverse curves.

 

This is a big backwards step. I have been dabbling with model trains for over 50 years and understand the issues, how is a newbie supposed to get absorbed by the hobby if the entry level items they buy in a packaged train set have an inherent fault?

 

 

Edited August 19, 2022 by john new
Image relocated/restored August 2022

[wasdavetheroad]

I found the modern narrow tension locks were less reliable than the older wider types. Apart from the width of the bar the latest types have flexibility in the bar and hook. Older types have a rigid bar and the flexibility is in the hook.

 

So I am converting all my   wagons for shunting , almost all 4 wheels, to Hornby medium tension locks, and leaving the long freights which are pulled on the main line with the narrow tension locks. I might convert the whole lot eventually. Some will be horrified at this but I don't care as I quite like the 'train set' look. Just having the hook on one wagon might help as well, especially if you can get that hook near the centre of the bar.

 

Apparently in Europe the most common freight coupler is the 'english type' so kadees are just as wrong as tension locks!

[newbryford]

On 11/04/2021 at 14:41, john new said:

 

 

That looks like the T/L is mounted too far back in relation to the buffers.

The curve/arc of the T/L should be outside of the buffer heads, otherwise buffer locking will occur when being propelled.- and may possibly occur when hauled, depending upon the length of the hook.

 

The FTG SPA wagon suffered badly from this. The instant fix in that case, was to pull the coupler out from the NEM box and apply a dab of glue to stop it moving.

 

Goes off to find a photo....

 

Found one:

 

Edited April 12, 2021 by newbryford
Found photo

[john new]

2 hours ago, newbryford said:

 

That looks like the T/L is mounted too far back in relation to the buffers.

The curve/arc of the T/L should be outside of the buffer heads, otherwise buffer locking will occur when being propelled.- and may possibly occur when hauled, depending upon the length of the hook.

 

The FTG SPA wagon suffered badly from this. The instant fix in that case, was to pull the coupler out from the NEM box and apply a dab of glue to stop it moving.

 

Goes off to find a photo....

 

Found one:

 

Agree yes that was the step 1 and too short a coupling (it is correctly mounted on the spiggots etc.). The other two tried and failed were the original and the alternative longer coupling both fail as although they extend past the buffers therefore curing buffer locking the hook swing arc exceeds the available loop space. The other identical wagon I successfully fitted with an old Tri-ang/Hornby pair from my scrap bin; fairly sure recycled from some old Mk1 coach bogies that had cracked and been replaced.

 

That hook swing arc is why the new small one’s are useless on tight curves whereas all my old one’s are fine whether on long or short wheelbase stock.

Edited April 12, 2021 by john new
Clarity

[john new]

An update, although I have not had much time to devote to this today a bit of hand shunting suggests that the small couplings are OK at 2ft/610mm as they run through the one point that is not set track when running on to /off the straights only option route other than through the actual Y. Next step will be loco shunting on that back siding to check that 2ft seems an acceptable minimum. Final step will be dig a few in-stock PECO points out of the track spares box and fit up a test track with 2ft or greater curves. (I have a Tracksetta).

 

The medium couplings size fitted to old Mainline and GRAFAR short wheelbase seem to run through the wiggly reverse curves section OK, as do all my vehicles with the larger, older, Triang/Hornby size whether long or short wheelbase.

 

The two long wheelbase Bachman, Whisky hoppers with the medium size couplings retro fitted (and the from the same set Brake Van with the original tiny type) still derail other than through the 2ft radius point - their sister fitted with the larger recycled Triang/H size seems OK.