N scale Body Mounted Couplers vs Truck Mounted

[drgw0579]

At one of my friends operating sessions this past weekend, we had a continuation of the Body Mount vs Truck Mounted N scale Coupler debate.

My friend has been in the hobby since the 60's and has several hundred cars on his layout.  While a good number are traditional Micro Trains cars, all brands are represented.  Many are old enough to originally come with the original N scale coupler (sometimes called Rapidos).  That means of course, just about every car on the layout has truck mounted couplers.  He has good trackwork, and normally derailment free.  But sometimes when you are switching in the yard, you will have a minor derailment when shoving on a long cut.   We've talked about the possibility of converting his cars to truck mounted, but he has no interest; it would be a significant undertaking.  And there is some expectation that you need to do all cars, as mixed is a bit worse than all truck mounted.

We are seeing most of the newer (and higher priced) cars coming with body mounted couplers.  Should all be made that way?  An argument against is that for those with smaller layouts with sharp curves won't handle them.  You could counter by pointing out almost all current locomotives are body mounted.

Several years ago, we went cold turkey with knuckle couplers replacing Rapidos almost overnight.  Could the same be done now for truck mounted vs body mounted?  Should it?

Bill Kepner

[jdcolombo]

My thoughts:

1.  Body mounts clearly provide additional reliability (e.g., lack of derailments) when pushing cars through turnouts.  How much additional reliability depends on a number of things: the turnout number (smaller turnouts benefit more from body mounts); the length of the car (longer cars benefit more, up to the point at which you reach the maximum coupler swing) and whether you are pushing through two diverging routes, creating an S-curve of relatively small radius.  I've found this effect clearly visible when pushing cuts longer than 5 cars through small-number turnouts (4's and 5's) with 50' cars.

2.  I have never had a problem with body-mounts on sharp curves, as long as the rolling stock was matched to the curve.  Yes, if you're going to try to pull two 85' Trailer Train flats through a 9" radius, you're going to have issues with body mounts, because you will exceed the coupler swing.  But I've reliably used body mounts on 8" curves in an industrial area with 40' boxcars.  And why on earth would you be running an 85' Trailer Train flat on a 9" curve, anyway ?

3.  Mixing body and truck mounts is a big no-no, particularly as the cars get longer.  Over 60', forget it, even on relatively generous curve radii (e.g., 16" in my case).  If you're going to body-mount, you really almost need to go cold turkey and convert everything at once - although you can get away with mixing couplers on smaller cars with decent radii (40' on 12" radius should be OK).

4.  Switching to body mounts en masse is imminently doable, even for relatively large fleets.  Back in 1994, I converted about 100 cars all at once; about half of these were MT boxcars, which already had holes drilled for a body-mount coupler (you did have to finish drilling out the hole and tapping it) and the other half were Atlas cars.  This was before the 1015 coupler, so I used 1023's on my Atlas cars, and shimmed the bottom of the chassis as necessary; once you figured out how to do one, they were all pretty much the same, so the conversion became rote: cut a small square of .020 styrene; glue to the boxcar floor; drill and tap hole through shim and floor; put on coupler.  This would be even easier today with the 1015's, which are cheaper in bulk and easier to assemble (once you get the hang of it).  Some cars required innovation - some hoppers (both open and closed) back in the day lacked any superstructure to attach a body-mount to.  Solved with some .040 styrene strip or brass strip added in the appropriate place or there were even some conversion doodads available for a while.  Where there's a will . . .

Some folks love their truck mounts.  Fine by me, but I'll never have another truck-mount on my layout (well, except for the Kato PA-1 chassis, that has a rear truck-mount that would require drilling and tapping the chassis - but I'll get around to doing that one day).

John C.

[cjm413]

If frame-mounted couplers are the standard for HO, there's no reason why "sharp curves" should be considered a valid excuse for truck-mounted couplers in N (or Z)

[nscaler711]

If frame-mounted couplers are the standard for HO, there's no reason why "sharp curves" should be considered a valid excuse for truck-mounted couplers in N (or Z)

Especially if you think about it, the 18" curve is the general minimum radii track section in HO, while generally 9.75" curves are in N. We all know HO is literally twice the size of N (54% bigger I believe? Or is it 46%?) so you can't say that sharp curves is a valid excuse. Because in HO the 18" curves are actually sharper than the 9.75" curves in N. ( that is if the percentages work out correctly...)
Granted I think the mass of HO scale is what keeps alot of issues down compared to the mass in N. Which is probably why we have to add weights to our freight cars as well...

That does make me wonder though if we were to scale the N scale cars we weighted to 1:1 proportions, would they be overweight?  (I know its not possible as mass is consistent... I mean hell Thomas should have floated away in Antman.  )


Also sorry about the tangent... 

[davefoxx]

I have sharp curves on my layout.  My minimum radius on the mainline is 12-3/8" with a small section of 11-1/8" in a passing siding.  All of my rolling stock will navigate this, and I run primarily body-mounted couplers, with the only exceptions being cars not yet converted (I put the conversions on hold when DKS announced the ProtoMate coupler a few years ago- so I am now behind).  I am running long cars, including passenger cars and 89' flats, which will run fine, if you're careful.  Like the prototype, you may not be able to get away with an 89' flat coupled to a two bay covered hopper.  However, generally, rolling stock will run reliably, if all couplers are body-mounted.

That said, I have a minimum radius of 10" on the A&R trackage of my layout.  Here it's better to run shorter cars, if they have body-mounted couplers.  However, I will point out that my Kato passenger cars (Amfleet, Superliner, and Metra commuter cars- all with truck-mounted couplers) run great on these curves.  That said, as noted in this thread above, backing up long consists with truck-mounted couplers sometimes doesn't go well.  To minimize derailments, my consists are generally all body-mounted or truck-mounted couplers and not mixed.

DFF

[MichaelWinicki]

When I jumped back in the hobby in 2008 I figured I was going to have to body-mount everything to get reliable operation based on what I heard/read.

9 years later and about 70% of my rolling stock is still carries truck-mounted couplers. 

So what's caused the delay in body-mounting?

I haven't had issues operational issues.  My layout is 1970-based and the rolling stock chosen represents that era.  Obviously a great many 40' box cars but have many larger cars.

Curves... Switching... no problems. 

I back 12 car locals in & out of the yard and derailments are few and far between... And I'm using Atlas code 55 everything which can be a little more problematic.  Between making sure cars carry a enough weight and the low-pro wheelsets are properly gauged– The layout performs well, even with 70% of the rolling stock carrying truck mounted couplers.

[brill27mcb]

Remembering dimly back to my youth, HO truck-mounted couplers disappeared way back when Tyco dropped its "Talgo-style" mounted NMRA X2F couplers. N-scale is decades behind in evolving past this toy train holdover, and I welcome the change.

Rich K.

[cjm413]

Especially if you think about it, the 18" curve is the general minimum radii track section in HO, while generally 9.75" curves are in N. We all know HO is literally twice the size of N (54% bigger I believe? Or is it 46%?) so you can't say that sharp curves is a valid excuse. Because in HO the 18" curves are actually sharper than the 9.75" curves in N. ( that is if the percentages work out correctly...)
Granted I think the mass of HO scale is what keeps alot of issues down compared to the mass in N. Which is probably why we have to add weights to our freight cars as well...

That does make me wonder though if we were to scale the N scale cars we weighted to 1:1 proportions, would they be overweight?  (I know its not possible as mass is consistent... I mean hell Thomas should have floated away in Antman.  )


Also sorry about the tangent...

18" radius curves are more of a "train set" standard in HO.   However, most people that insist on sticking with them will make responsible decisions about the locomotives and cars they try to run on them vs insisting that manufacturers compromise the appearance of their products by jacking up the bolster height and/or making unsightly "cutouts" to clear a truck-mounted coupler.

[jpwisc]

I am in the process of converting my layout entirely to body mount. I have relatively large corners 22"+, so I have never had much of a performance issue with truck mounted couplers.

The main reason I'm switching is appearance. I like to take close up shots of everything and body mount look better to me. The prototype is body mounted, so I would like mine to be that way too. At some point I plan on adding cut levers to all my freight cars too, which is a breeze on a body mounted couplers. I also don't like the look of a coupler swinging on a tail end car as it heads into a curve. I know it's little, but it breaks down part of the illusion for me.

[nkalanaga]

John C:  An even easier way to convert MT cars to 1023s is to forget gluing the shim to the car.  Drill a 1/16 inch hole in it, tap the hole in the floor, and use the shim like a washer.  You get the same results, but without the glue.

If one is really lazy, and can afford the extra cost, use Evergreen 3/16 inch wide strips, drill a 1/16 hole every 5/16 inch, then cut the shims apart.  Much easier than drilling them after cutting.

If you want to lower your cars (not mentioned in this post), forget the shims and file the body bolsters until the coupler is at the right height.

[randgust]

I use truck mounts for about 90% of my cars, and I have some significant switching that involves backing 20-car cuts through my yard throats and over crossovers.

I think WHERE truck-mounts cause derailments when backing up should come up in this discussion.    I'd come to the conclusion that most derailments happened with the flanges either picking the points or picking the frog points of Atlas C80 switches.     The points can be rough and touched up with a dremel disk and even inset into the stock rail a hair.    I made a practice of cutting my frog points back so that an MT wheel wouldn't pick them even if forced.  You can alternatively fill the flangeway a bit, but I prefer to cut back the frog and sharpen it a bit.

Other than an occasional car that's just way too light (think an empty MT 34' hopper on the very front of a 20-car cut backing through the diverging side of a #5 turnout) I have no predictable derailments. 

I won't contest that it doesn't put the forces in such a way that it increases derailment potential, but I think if you study it you'll see that there's some commonality here with where and what happens.   Cars don't just pop off when backing up on tangent track, but if you've got any bad track in there and ragged turnouts, yeah, backing truck mounts will find things nothing else will.

I use magnetic uncoupling so the truck mounts improve keeping the coupler vertically and horizontally aligned to the centerline.    I also use body-mounts, and except for the problems with 85' passenger cars and piggybacks with each other if they have body-mount vs. truck mount, haven't seen much to get excited about, really.   Its not like they don't work, just that converting everything over is unnecessary.   I've decided my time is better spent lowering the body shells down on the frame.

[jagged ben]

I have to disagree that mixing body mounts and truck mounts is a 'no-no'.  It depends highly on the details.  For example on sharp flat curves you'll have problems if you try to couple a 30ft body-mounted car to an 89ft body-mounted car.  Change the 89ft car to a truckmount and you'll be able negotiate the same curve.    On the other hand, switching 89ft cars with truck mounts is generally quite unforgiving, so if your curves aren't too sharp it's worth body mounting them.  This is because the distances from coupler to truck center is greater, which amplifies the torque on the truck.  With shorter cars this is less of an issue.

As far as switching goes, I've done a LOT of switching with mixed consists of shorter cars, and I've never noticed problems that correlate to the coupler mounting.  Generally, the solution to derailments is to improve the track.  It's only with long cars that you can cut yourself some slack on your trackwork by body mounting.

One last thing: body mo7nts are less forgiving on heavy trains going upgrade on sharp curves.  It's a trade off with the switching.  If you can't broaden your curves, maybe don't be so quick to body mount.

[jdcolombo]

I'll make one last point that has been raised tangentially in a prior post:

The prototype uses body-mounted couplers.  If we want to copy the prototype as much as possible, then our couplers should be body mounted. 

That said, like everything else in this hobby, it's up to the individual to decide whether that aspect of prototypical look is important.  But we've come a long way in nearly everything else - finer and more accurate details on everything, more accurate measurements for locomotives and rolling stock; recognition that weight matters, and an effort by manufacturers to provide cars with better weight; low-profile flanges on detailed metal wheels; code 55 track (and in some cases, Code 40); sound; etc.  In such an environment, truck-mounts seem anachronistic. 

John C.

[Point353]

... low-profile flanges on detailed metal wheels ...

What (extra) details do these metal wheels have - and which ones are they?
Are there some specific details that plastic wheels, for example, are lacking?

[nsbob]

I'm sure someone else can name others, but Fox Valley Models makes metal wheelsets  with either semi scale fine wheel tread or wide wheel tread.  I personally think that the profile of their semi scale fine tread wheelsets are more prototypical than any plastic wheelsets manufactured.