Large Scale Central

Operational disadvantages of truck-mounted couplers? What?

Modeling Rolling stock
#1

Hi, All

I hope this is the right forum for this. My question, respectfully submitted to the wisdom of this group, is:

Will someone please explain to me exactly how body-mounted couplers are superior to truck-mounted couplers for OPERATIONS? How do truck-mounted couplers adversely affect operation, if they do? I really would like to understand this point.

(I’m much less concerned about the appearance and prototype fidelity advantages of body mounts, which I understand already).

A related minor question:

Now that I’ve moved outdoors where radii are much larger, I’d like to replace the unsightly hook-and-loops on my (mostly) LGB rolling stock with operating knuckles. I think the Kadee 831/1831 is a drop-in fit. If someone could confirm that, I’d appreciate it.

I will listen carefully to any advice you care to offer. Thank you very much.
Steve

#2

The big problem with truck mounted couplers is how the pull on the cars in the train. Truck mounts tend to pull the cars inward, toward the middle of the arc of the curve, and can pull cars off the inside of the track. Body-mounted pull the car along the track.

#3

Steve; The Kadee 831/1831 is a good fit for most LGB cars. Number 1831 is considered a #1 scale coupler (1:32 scale). It is much smaller and a LOT less forgiving of the irregularities that can happen to outdoor track than the 831. Both models will couple to each other, however. I won’t try to influence you about 831 vs 1831, but do want you to know that shifting track alignment can cause the 1831s to separate more readily. Kevin Strong uses the #1 models of Kadee couplers very effectively on his garden railroad, as they are about right for the size couplers used by the EBT in 1:20.3. I’m hoping Kevin will add his experience to the thread. I try to use the “G” model Kadees for the most part, since my trackwork in the past was never that perfect - and likely will not be so in the future. Presently don’t have a layout. With the LGB locomotives you may have to get creative, but the Kadee site has a lot of good advice.

(http://1stclass.mylargescale.com/davemeashey/2090_001.jpg)

Best, David Meashey

#4

Bob has it right on… And to add to that, during operations railcars are frequently pushed backwards into industries and sidings… Truck mounted couplers put all the backing force directly on the wheels, sometimes not allowing them to follow the rails, and therefore you get derailments… The longer the train being pushed back, the more force is placed on the trucks…

#5

Dave…Thanks. That answers the question perfectly.

Bob, Andy…Okay, that’s quite clear explanation. Thank you both. I wonder if I might I try your patience a bit further?

I assume both the pulling and pushing effects depend on curve radius as well as train weight. Is there some radius above which this is likely to be a negligible effect? The tightest curve on the DC&M (so far anyway) is 16 ft radius. R7 switches, deep flanges, code 332 rail, and 20 car trains. Does your experience suggest derailments are likely if I stick with Talgos?

(It’s not just that I’m lazy–I admit that–but I’ve never fitted body mounts to rolling stock and I’m not sure what I’d be getting into.)

Very helpful, guys.
Steve

#6

Steve,

Prior to my switch over to 1:20.3 (where talgos are unheard of) I ran numerous LGB/USA/Aristo trains with truck mounted couplers just as you describe on 8ft dia curves. No problems. 5ft dia did cause me some grief backing up. At 16 ft I doubt you’d experience any trouble (assume 16 ft is the diameter?). I would add that “hook and loop” had no issues backing up on any radius track but knuckle couplers did.

A side note…My logging disconnects (AMS 1:20.3) are “link and pin” and by their nature are “truck-mount”. They often derail when backing up on a 10 ft dia curve. The Link and pin are forced off center when reversing.

Body mounts are a pretty simple conversion you may want to consider anyway…If I can do it, anyone can.

Mark

Edit: All my 1/22.5 - 1/24 rolling stock are equipped with heavy brass wheels and deep flanges (San-Val), likely helps in keeping them on the rails in both directions.

#7

Mark…thanks for the practical data. It’s very helpful to know Talgos didn’t cause trouble on your eight-foot (4 ft radius) curves.

“(assume 16 ft is the diameter?)”

Nope. The sharpest curve on the DC&M is Turnback Curve, at 16 ft radius. The switches are all R7’s, which I think means they have a seven-foot equivalent radius. Sounds like they’ll be okay.

Steve

#8

Dang!

Ask a question, get exactly the sort of helpful answers I needed. I knew there was a reason I like this forum so much.

Thanks to all
Steve

#9

If your running trains that are only 3, 4, 5, 6 cars long, and pushing backwards on the broad a curve, you may not have any problems… You haven’t stated what train lengths you’ll be running… Another factor to consider would be the car lengths… I used to back coal cars into the inside storage tracks on the club layout with about 18 cars in the train and all had steel wheels, and they always jumped the tracks about midway thru, trying to push too much weight thru the switch… These were LGB wide radius switches… I don’t know the R-number…

#10

I think he mentioned 20 car trains. Your “point” about switches is a good one though…The LGB switches could be problimatic with deep flanged wheels!

#11

I still use both. All of my 1:20 stock is body mount and all of my 1:29 / 1:24 stuff is truck mount. I dislike the use of Talgo to describe truck mounts as it really isn’t accurate, but it’s used kind of like Firigidare™ was in in the 50’s and 60’s. so there’s no getting away from it.

For years I was indoor only with R1 curves (4 ft dia.) and switches. While I never ran really long trains, but never had problems backing through curves and switches.

I’d give both a try and see which you prefer. The truck mount conversions are the fastest but once you see body mounts you may decide they are worth the extra work for appearance alone.

#12

First off I am using mostly all truck mounted couplers, Kadee 831 to be exact with all metal wheels. When I was using LGB switches I could easily push up to 14 cars through a cross over consisting of two wide radius LGB switches. Trains of up to 20 or more cars are no problem as long as the cars roll freely and you’re not using under 8 foot diameter curves (assuming of course reasonably aligned rail joints and track without violent dips). I mention this only to reassure you that truck mounted couplers will work just fine if that’s your choice within the parameters mentioned.

Having said that:
Body mounted couplers are generally better first, because they look more prototypical and second, because they allow longer trains and the ability to shove longer strings of cars.

The reasons for my choices:
I insist on working front couplers on my steam locomotives and dislike seeing a horribly butchered up pilot in order to accommodate a working coupler. As a result I cut the coupler shanks back and mount them close in to the pilot for better looks. This inhibits their side to side movement somewhat and causes some derailments to body mount cars while switching. I would rather have the cars’ looks compromised than the engine’s.

I chose the “G” 831 instead of the smaller #1 size because after testing both I felt that the “G” size operated slightly better (both were quite good) and they were more forgiving on rough track due to greater depth. Additionally while the #1 size is most often found on narrow gauge in the east the D&RGW used full size (standard gauge) couplers on their narrow gauge and the “G” are closest. Your geographical location may influence your choice here as both sizes give very good performance. Also #1 size is closer to right for 1:29/1:32 scales.

If you have any doubts buy a couple pairs of each size and try them out and check their looks. It’s worth the few extra dollars to get what you’re most happy with.

#13

Dave, I have that same yellow LGB switcher ripped apart doing some upgrades, glad you posted the photos, to give me some ideas.

#14

Wow…more good information. Plenty to ponder there. Richard, Jon, Andy, and All…thank you.
Steve

#15

contrary to what has been expressed here, i beleive, that the only advantage of body mounted couplers is the realistic look. as to drawing and pushing in curves, the longer a car is, the further to the outside of the curve moves the connecting point between cars. if we regard the trucks as very short “cars”, we see, that their point of connection is less to the outside of the curve, than in case of body mounting. the further to the outside the connection is, the bigger the forces towards the inside of the curve. (one can add, that the lower the couplers are mounted, the less force is trying to tipple the cars over towards the inside of a curve) so it should be safe to say, that apart from a low center of gravity,(metal wheels etc) truck mounted couplers are a big help, not to have derailments in curves.

(http://kormsen.ko.funpic.de/bahn/kuppelschema.JPG)

#16

Korm Kormsen said:
so it should be safe to say, that apart from a low center of gravity,(metal wheels etc) truck mounted couplers are a big help, not to have derailments in curves.

(http://kormsen.ko.funpic.de/bahn/kuppelschema.JPG)

I found just the opposite to be true. When you’re backing up a long string of cars, especially going through a curve such as a turnout, all the side force is transferred to the first axle closest to the coupler and has a tendency to force it off the rail (usually the car closest to the pusher). With the couplers mounted on the car, that force is removed from that axle and transferred to the cars. At least, that’s been my experience.

#17

Lets think about it this way… which way do the big railroads order their cars, truck or body mount??

Also, except for the el-cheapo tyco/bman cars in HO, as far as I know, body mount is standard on everything in HO.

#18

One of the problems with those drawings is the fact of scale… Looking at the drawings and the freightcar size… Given a standard aristo 40 ft boxcar at 16 inches long, the curves shown would be about 36 inches in diameter, which greatly exagerates the shown forces…

Ken’s explanation to me is right, with trucks mounted couplers, the force is always on the wheels and that’s usually what forces them to de-rail…

Any movement of any scale is going to cause forces to act on the vehicle in motion… Truck mounting, or body mounting is basically a personal choice, depending on the individual… we can argue pro’s and cons of either way, till we all turn blue and still not get anywhere…

Most people who operate on small diameter curves usually prefer truck mounted couplers, while most people who operate on large radius curves prefer truck mounted couplers… And, of course, theirs always the exception… :slight_smile:

#19

All;

A piece of advice I got from one of the staff of my local hobby store that applies to both the body and truck mounted couplers. I’m sure each of us has had centering springs launch straight through the space/time continuim while trying to assemble Kadee couplers. (I say that they launch through the space/time continium because they are seldom found right after they fly away - one usually finds them weeks, or even months after that event, therefore, they must be flying into the future!) The package always has extra springs, but flyaway springs are annoying. The gentleman I mentioned suggested placing a small dab of Walthers Goo in the back corners of the draft gear box before trying to compress the springs into place. The Goo stays flexible and will not inhibit the flexing of the springs, but it does keep them from going balistic while you are trying to fit the springs and the coupler into the draft gear box. I have been using this trick for several years now. Thanks to this trick, I have a lifetime supply of extra coupler centering springs.

Yours,
David Meashey

#20

As for mounting, you should get a KD height gauge and then
cut, shim, alter–whatever it takes to body mount.
I’ve been body mounting my couplers since day 1, when KD invented
them I guess. :slight_smile: :slight_smile: :slight_smile: