MT Heavyweights in operation

[Cajonpassfan]

As I am doing test runs on my Circa 49 LA Division layout, last night I decided to make up a new, generic 12-car heavyweight train made almost entirely of MT heavyweights: baggage, Mail/baggage, a couple of coaches, diner, Pullmans. Kind of a stand-in consist for my future California Limited. They are all brand new cars I acquired over several years and never before run.

What a disappointment... I’m getting multiple random uncouplings between several cars, and derailments in places other trains sail through smoothly. And on top of that, the train looks silly with the giant gaps between cars (but I knew that going in and figured I’ll need to do something about closer coupling when the time comes). I have what I believe is decent trackwork, 18” minimum radii in a few places (derailments occur there and elsewhere, and on turnouts) and 2.2% grades.

I only had time for a cursory look at the problems last night. The cars seem relatively light for their length, 1.3oz, but my Kato cars are lighter and track beautifully. The six wheel trucks seem to flop around a lot and have that odd, off center mount.

So...before I start looking for a solution, does anyone else experience these problems and if so, what’s the fix? (Is there a simple fix? I’d rather not go the 905 route, except maybe on some head end cars that might be switched, the rest of the consist will remain relatively same). I like and need these cars for my era, but it’s a bit disappointing that RTR equipment is turning into yet another “project”.

Thanks,
Otto K.

[peteski]

Kato cars have those nowadays universally-shunned truck-mounted couplers.     In my experience those are a good thing in on long cars (even if they are unrealistic).   But what do I know . . .

[Kev1340]

I’ve had the same uncoupling issues with these cars going right back to the MOW set. I had intended collecting quite a few N&W cars, but after the first few exhibited the same problem I gave up.

Hopefully someone has figured a fix, as I’ve been unable to so far.

Cheers,

Kev

[bbussey]

Drill and tap new holes for #00-90 screws at the back of the coupler pad to move the couplers in. Swap in FVM 36” metal wheelsets. Those modifications should resolve your issues.

[Maletrain]

I have not had the occasion to find that problem much less figure it out, yet, but I have a bunch of those cars that I intend to run in similar length trains on similar radius curves, some day.

Based only on reading the 'Net, my original thought would have been to let the MTL couplers swing on their mounting screws, or replace them with some dummy knuckle couplers that mount only with a screw through a hole in their shank.  I think Unimate made some like that.  But, those ideas would only work if the problem is that the coupler swing is not wide enough to prevent the coupler shank from hitting some fixed surface on the car and causing a derailment with the side force.  And, if some parts of the coupled cars are actually touching on the curve, then only longer (and less realistic) coupler shanks and car spacing would work.

But I just put a pair of MTL heavyweight cars on some Kato track with 19", 15" and 13.75" radius curves and #6 and #4 turnouts, and pulled one with the other by hand (because the tracks aren't wired).  Nothing seemed to touch or bind.  So, maybe the problem is that the increased resistance of your longer train is pulling cars off the inside of the curve (string lining)?  Have you tried incrementally adding cars, starting with 2 or 3, and seeing what happens as the # of cars increases?

Another thought is that the RPOs are only 63', while the coaches and Pullmans are 80' and longer, so there is a car end offset on curves that doesn't match between the RPO and longer cars.  Are your derailments consistently occurring with the car behind the RPO?

The uncouplings might have something to do with coupler heights not being correct on all cars, or perhaps due to sharp grade changes in the tracks.  Truck mounted couplers are somewhat more forgiving than body mounted couplers for sharp changes in grade on long cars, because they move up and down as well as sideways.  Did you check your coupler knuckle heights with an MTL gauge?  (If you don't have one, did you at least make sure that your coupler knuckles are all the same height on the cars that you are running?)

I think that all of the MTL heavyweights are new enough that they should have come with the "reverse draft angle" modification to the knuckles, but you might want to check that on your particular cars.  That mod was specifically to prevent unwanted uncoupling (caused by one knuckle slipping over the other).

[Outa thoughts, hit send.] 

[CBQ Fan]

I have had several over the years where the truck pin was inserted so tight that the truck couldn’t swivel freely causing odd derailments.  Loosen it up a bit and problem solved. 

[Lemosteam]

Otto, all.

The MT heavyweight couplers are designed to swivel on their mounting pins (they do not have screws). Check to make sure they swing easily. Thinking metal wheels will help as well, as per Bryan’s suggestion.

[bbussey]

With the exception of the RPOs and SWCs, I’ve moved my couplers inward so all of them are screwed tightly and do not pivot. Even with the RPOs and SWCs, I remove the coupler mounting pins And tap for #00-90 screws. I’ve never had derailment issues, whether traversing through curves or crossovers.

There is a lot of play between the standard plastic wheelsets and the trucks. The tolerance with FVM wheelsets installed is much tighter.

[thomasjmdavis]

Interesting that within the thread, there seem to be 2 solutions- one to tighten the couplers and the other to check that they are loose enough.

But given my own observation, both actually make sense to me.  Where I have had issues are situations where, after going through a curve, one or both "swivel" couplers gets "stuck" at an angle (not loose enough)- which when the train is out of the curve and on straight track is either uncoupling (if the coupler has wedged toward "open") or adding to derailment chances (if the coupler is wedged the other way).  If properly adjusted for "loose swivel" operation, the wedging on a tight curve (or turnout) should not happen.  But a rigid mounting also avoids this, since the coupler does not get out of alignment in the first place and seems like it works without fouling anything - or at least it did on the 15" radius with easement curves of my last layout.

I suspect that which works better on a given layout with a given mix of equipment will vary from one layout to another.

So, on the cars that I am kitbashing or using as cores, I am going with moving the couplers inward and screwing them in place- which is more consistent with the other body mounted couplers I have. 

My best guess has always been that the "swivel and wide spacing" has something to do with negotiating tight radii.  And on the offset bolster, I suspect it also has something to do with that, plus being obviously easier to mount at the factory.  Not a novel design though.  I have 30 year old Pecos River cars with offset bolsters. (I have collected the PRB cars since the last working layout, so truth be told, I don't know how well they track).

but my Kato cars are lighter and track beautifully.

On my previous layout, I made the mistake of testing the track by running my Super Chief around the layout.  Absolutely no issues.  Then I tried to run ANYTHING else.  Rapidos and Walthers passenger cars did not like one curve, and found one particular "kink".  Freight trains lost cars (derailed or uncoupled) to one particular switch (that was just never quite right and eventually replaced).  But the Katos?  Didn't matter what the problems were, as long as the tracks were connected to each other, the Katos had no problems.

I think the Kato instructions are along the lines of "open box, put train on track, operate train, stop train after 10000 hours of operation and inspect for wheel wear and lube locomotive, resume operation".

[davefoxx]

What couplers are installed in the MT cars from the factory?  Is it a situation where you can replace #1016s with #1015s to pull the cars closer together?

Hope this helps,
DFF

[thomasjmdavis]

What couplers are installed in the MT cars from the factory?  Is it a situation where you can replace #1016s with #1015s to pull the cars closer together?

Hope this helps,
DFF

Unless the cars I just checked are different from others, they come equipped with 1015s.  At least, that is what they look like to me (and I just assembled 20 pair last week).  I should note to be fair, that the distance between cars (that I just measured with my trusty really cheap caliper) is 0.375 to .038 (depending on which cars)- which is roughly 5 scale feet.  I don't want people thinking they are 8 or 9 scale feet apart like some early N scale cars were.  Diagrams I have (plus recollection of having read other sources), indicate that the coupling distance for heavyweights should be 3' more or less (the distance from the end of the car to the pulling face varies a bit from car to car).

Now, space between cars being 2' over is certainly not the worst for N scale, and I'm sure they did it to accommodate modelers with tight curves and such (which reminds me I need to do an experiment with my Peco crossover before I commit to any more "corrections" of spacing).  And frankly, it doesn't bother me to move the coupler- its the sort of thing I do while watching TV in the evening.

[bbussey]

The RPOs come with 1023s, everything else comes with 1015s.

[altohorn25]

Replace the factory couplers (usually 1015's) with Z scale 905's.  This shortens up the distrance to close to prototypical between cars.  If you paint the couplers, they'll have a little more grip and you'll get rid of unwanted uncouplings as well.  See attached photo.

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[altohorn25]

Here are some more examples of the couplers replaced with Z scale 905's.  The beginning of the video shows my Royal American Shows carnival train with MT coaches and sleepers at the end of the train with 905's installed.  No issues with uncoupling and you can see how close the cars are.  Fast forward the video a bit (to time index 2:00), and you see my PRR T1 with a mix of passenger cars.  There are MT heavyweights in this train as well with the 905 coupler modifications.  I do this to all my MT heavyweights and have very little probelms with them (I don't run on anything less than 19" radius):

[muktown128]

Nice weathering job on the PRR T1 and passenger cars - subtle and really brings out the details on the running gear of the T1.