One thing is for sure… Hook and Loop couplers are practically sailor proof, and that is saying something. 
Actually, I had some issues once with some H&L equipment on my very early test loop.
It seemed that I had “double hooks” and on sharp curves, the hooks would hit each other and not let them “move within the loop” and I got derailments.
I never quite understood how double hooking would work, until I heard that many people single hook (which then means you have to worry about which way a car is oriented), or I have seen hooks that swivel from side to side, but have seen those hang up too.
So, maybe this is an opportunity for the H&L aficionados and experts to help educate me and others on these issues I saw in my first experiences.
I’d love to understand the “official” answers from the “official society” 
Greg
We’ll get back to you just as soon as we can find the phone. We were celebrating the arrival of Spring and Fr Fred was dancin’ nekkid. That required large draughts of Holy Water to tolerate the sight. Not sure when we lost the phone, probably when we had to send out for more Holy Water.
We think the phone is buried under a foot of snow, so it may take some time to dry out. 
…the hand cranked telephone is frozen, and the string broke on the string and can system…but, the solution to the twin hook loop and hooks is to avoid those 2 foot radius curves…
Yep, that was the first thing I learned… set up an oval with 4’ diameter curves with LGB, Aristo, and USAT track.
Put my shiny new F3 on it and watched it derail on the curves.
The loop did serve another purpose though, wanted to see how the various rails aged, and what color they aged to.
And of course showed me that hook and loops did not double hook on tight curves.
Living one mile from the ocean showed me how brass can oxidize overnight.
So the loop saved me money in many ways.
Now, SS track, 10’ and greater dia curves, and Kadees.
Life is sweet.
Greg
p.s. skip the phone call, sounds like the hand crank and the string are at about the same technological level as the H&L’s …
p.p.s was hoping to learn something about single and double hooking, but maybe this is an “for entertainment only” my apologies
Greg, check with John le Forrestier, he is a confirmed hook and looper, though I don’t know if he uses single or double hooks.
I will, I actually have now remembered my experiences, and someone must have come up with ways to deal with it better than I did.
Hope you guys thaw out, I feel guilty every afternoon driving home and have to turn on the air conditioning to cool the car off. 
Greg
I really like the H&L’s for open houses, never seen them disconnect when using them in pairs.
But I do have Kadees on my heavyweights, and my little Hartland junk train shorty cars.
These work very well when body mounted.
The best thing about the extra packets of H+L/L+H that come with new models is the cash that you can realize when selling them.
There is always a good market in the UK for them.
Well Seve and Greg, I’ve kept out of this discussion so far because who needs to
get laughed out of town by a huge majority of folks who use knuckle couplers.
For some reason it’s always been very easy for folks to get mighty steamed up about the kind of string they tie their toys together with.
This is not to suggest that my hooks and loops are perfect - they are not.
The gravity operated tension-locks refined over several generations by Hornby in England are perhaps the best h&l’s in the world.
These couplers are tilted left to right so the loops contact minimally and cannot interlock, and the whole system, including the uncoupler ramps, works, as far as I have been able to test them, almost flawlesswly.
Needless to say, these 00 couplers are unsuited to our large-scale trains, so I have had to settle for the LGB/Bachmann type, which are actually a pretty poor example of H&L couplers. For a stert they are upside-down. The hook is beneath the loop, so it must be held upwards by means of a spring; I would prefer a springless version.
However, we can uncouple these H&L’s with bare hands, which is a priceless advantage.
So what are the virtues of this coupler? Why would a serious model railroader use them? I’ll try to resist the temptation of explaining what is wrong with the various knuckles. That is a subject unto itself, and may only upset some people needlessly. I believe most honest users will probably admit they see some weaknesses anyway.
I switched over to hooks and loops a few years ago after demonstrating an LGB starter set to a lady buyer. I was impressed by the following observations:
First, these couplers worked every time, not just on the straight parts of my demonstration oval, but, amazingly, on the 2’ radius curves as well.
Second, the lady and the young child for whom she was buying the set easily saw and understood the couplers and were able to manipulate them for coupling and uncoupling without instruction from me. They were able to operate the couplers with their bare hands and needed no tool to assist them.
Third, the more I saw of these couplers the more acceptable I found their appearance, believe it or not. To this day I still admire their minimum profile, their light weight, and sag-free stability. I am long past the point where they seem odd-looking. I really hardly notice them, whereas I certainly do notice the knuckles I see in 'photos or on other folks equipment. But 'nuff said…
I have a smallish urban backyard; curves are tight: 30" radius on the branch, 4 ft radius on the mainline. I use LGB #1600 switches on the main, LGB #1200’s for the spurs and yard trackage, or Aristo ‘equivalents’.
My Littleton and Smallville Railroad is a fully operating pike with a heavy emphasis on freight switching. I have many guest operators, frequently very youthful or inexperienced.
In the days when I used knuckles, I spent an inordinate amount of time demonstrating them to these folk. They often seemed frustrated by knuckles of whatever make.
What I saw during that lady’s demonstration changed things forever. The H&L’s operated so well on curves meant that my novice operators could now manage quite well on their own. The odd appearance of H&L’s seemed a very small price to pay in exchange for virtually trouble-free operations. I would change over to h&l’s and keep my fancy knuckles in a box for that day when we had all grown up.
The day never arrived. The changeover raised the fun factor a hundredfold.
To answer another question: I use only one hook per car. All my cars are aligned east-west, and they stay that way. just like on a real railroad. With the odd exception, no doubt.
The single hook on one end of each car is the system first introduced by LGB wayback. For want of a better term I call these cars polarized.
My track is on wooden benchwork <>39" above ground level, and is level. If the couplers do part in operation, it’s always because of a track problem - or more accurately a benchwork problem. One or two of these crop up in the Spring, especially after a Winter like this has been, when I can expect some settling of the pillars supporting my benchwork. A little levelling soon fixes it.
One hook on one end allows these couplers to be uncoupled anywhere with a single finger pressing down on the upward-pointing tab on the hook.
Two things can cause problems: Double hooks, as Greg has pointed out, can get interlocked on tight curves and s-bends. Also, the Aristo Craft H&L’s have teeth on the underside of the loops. These appear to be intended to keep the hook centered in the loop, but they limit the hook’s lateral movement too much and will twist a car right off the track at a crossover made of two 1200 switches, or anywhere else that you have an opposing pair of 2’ radius curves. I have very few of these couplers, but for what it’s worth I have carved these teeth off the loops.
The loops, especially those not equipped with LGB’s stronger centering spring, can wander off center and so fail to couple. You have to watch for this and center the hook manually. Fortunately all my operators get this right away, and have been able to cope without a lot of grief.
I hope this hasn’t offended the knuckle afficionados too much. Each to his own. Cheers everyone!
Thanks John, I did learn some interesting things from your post.
And it did now remind me of wondering at the strange “teeth” on an Aristo H&L.
A question though, not to be argumentative, but I never heard that railroads maintained a “polarity” on common rolling stock on a railroad. Do you have some references for this? I’m interested in why this would be, unless it was to keep the brake wheel at the same end of every car…
Thanks, Greg
Hi Greg & you’re welcome. I meant that once the car is set on a model railroad it won’t get turned around in regular operation. However the prototype is a different matter. I stand corrected.
Your question draws attention to the fact that in interchange service a car could easily return the other way 'round. Good point.
Doubtless there are situations where freights roll over a wye for example, and cars come back turned around. In any case, on my own home pike it never happens, and probably wouldn’t on most of our railroads. My own short line doesn’t turn cars around anyway.
As for aligning all brakewheels in the same direction, I don’t think so!
There is a huge advantage, by the way, in having only one hook per car. A single finger will uncouple them.
With the double-hook system which LGB later offered as an option, two hooks must be depressed simultaneously. This cannot be done by the unaided hand. I found this option self-defeating.
It seems a shame to me that these LGB/B’mann type h&l couplers do not have the tension lock feature which I mentioned in connection with Hornby’s variant. This consists of a tooth at the end of the hook that engages the loop. Thus, slack is required to uncouple. It does give considerable insurance against couplers parting in a running train. As I said, however, I have not found parting to be a problem as long as my track is in good order.
As a footnote, Hornby couplers are made of pressed steel and are body mounted.
Truck mounted couplers a la LGB/B’mann work exceptionally well in my own circumstances, which, as I mentioned, are rather tight.
Thanks again John, you have confirmed my “take” on the double and single hook situations.
Yes, the “tooth” is analogous to when Kadee put the “tooth” on the inside of the knuckle in HO to keep cars from uncoupling over the magnet when there was no slack, that and the delayed uncoupling were definitely milestones in functionality.
In my case, not only do I have a wye in my layout, but it’s at one entrance to a double-ended yard, and I encourage running trains in opposite directions on the mainline, so quite often a freight can get “turned” several times by entering the yard, having the caboose (I’m old school) and the motive power cut off, and then leave the yard later in the opposite direction, after having cars taken out and added. In fact my yard is set up for 2 operators since it is double ended and has 2 lead tracks.
So thanks for the education, I kind of miss all the technical or educational threads we seemed to have …
Regards, Greg
In your situation, Greg, if I were determined to stick with H&Ls - mostly out of consideration for my amateur crews, but for the other virtues I’ve mentioned as well - I would mount hooks on both ends of my rolling stock. Where freight operations are going everywhere, I would equip everybody with an uncoupling tool because a single finger is all you can fit between the cars and that just won’t cut it.
A credit card slipped down between the loops will push the hooks down and disengage them both simultaneously, which is what is required. A popsicle stick also works. A tool with a handle, such as an egg lifter or spatula, is better still.
I think it’s too bad if one has to resort to a tool, and that is the main reason I’ve stuck to the single hook system. I guess I really am an advocate for simplicity!
Sorry for the delay in replying; I had forgotten to click Watch Topic. Cheers.
In the thread by Boomer Keel relating to 1:20.3 Billboard reefer madness I posted a new reefer (actually 1:24) which hopefully the USPS/Parcel Force (UK) will deliver here in one piece. The last item from the States arrived damaged and nearly eight months later I am still awaiting news about it.
Anyway keen observers will spot the hook and loop (or vice versa) couplers.
Savor them whilst ye may!
They will be replaced by Aristo couplers once the car arrives here.
Sad to say Alan I had many of the H&Ls had I known that someone would actually buy I would not have thrown them all away. Later RJD
Actually RJ those couplers are popular over here. So, I have sold many packs and was able to buy replacement Aristo ones in their place.