Notes on body-mount couplers (work-in-progress)

[GaryHinshaw]

As I noted in Weekend Update, ever since Craig@BLMA plied us with his new trucks, I've been struggling to come up with a body-mount coupling scheme that is worth the trouble and that plays well with (near) prototypical ride height.  This thread is/will be a quasi-random collection of notes on schemes I've been trying.  I don't have anything I'm really happy with yet, but I thought I would throw some ideas out in the hopes that it might lead to something better.  Feedback and suggestions encouraged.

Thanks,
Gary

[ednadolski]

Thanks Gary!   This will be very helpful for those of us who have struggled with this.

Ed

[victor miranda]

MT 2004 does not work ?

victor

[GaryHinshaw]

I won't go into body-mounting MT's since there is plenty of excellent literature on that.  In any case, I have been looking for alternatives to MT to avoid the slinky effect, so I started to look more at Accumates and McHenrys.  Since McHenrys don't come with pockets, one has to make something up for body-mounting.  I was intrigued by Bryan Bussey's idea of using rectangular brass tubing to make coupler pockets and came up with a minor mod that I thought I would share.  The basic parts are shown here:



The pocket is 3/32 x 3/16 brass tubing.  The Accumate is top left, the McHenry (with a 1-72 screw in the shank hole) is top right.  The mod I made is to use a 1-72 x 3/32 set screw (headless) in place of Bryan's 00-90 screw + 1/16 tubing combo.  Here is a shot of the set screw in place w/o the coupler (sorry about the Sasquatch focus):



To assemble, just start the screw, add an MT truck washer on the bottom (sliced a bit to fit), insert the shank, then set the screw.  The result, especially with the McHenry, is an extremely robust assembly:





It works equally well with the Accumates: (no more exploding Accumates with this)





In this example, the set screw is 1/8" back from the pocket face.  It should probably be back a bit further with the Accumate.

The advantages of this approach (all true of Bryan's version) are: extreme strength; customizable pocket length (e.g., extended draft gear), and relatively low cost.  The additional advantage of my mod is a slight simplification: no need for the interior piece of tube, and no need to trim the set screw.  The disadvantages are: the rectangular tubing is not trivial to work with (unless you have the right tools); the Accumates & McHenrys are really big; these pockets wont work with MT's because there is no easy way to install the centering spring.

I'm still open to this approach, but the coupler size puts me off.

[BN1970]

I have been able to order bulk Micro Train pockets both 1025s & 1027s (in zip lock bag of 50) via my LHS who adds them to their monthly Micro Train order for about $25 CDN.  However I do wish that Micro Trains would sell x10 pairs of 1025s & 1027s like they do the 1015s. --Brian

[GaryHinshaw]

As I noted in the Z scale forum, I was intrigued by the new Full Throttle Z scale couplers.  Functionally, these are basically smaller versions of the McHenry: similar shank design, and 2-part knuckle, except that the knuckle spring is a plastic leaf spring inside the pocket.  See DKS's extensive review for more info:

http://jamesriverbranch.net/clinic_2.htm

From my perspective, this is close to the perfect design, and they're close to the perfect size for N scale.  But (there's always a but) they are only available mounted on Bowser trucks and they're expensive: $5-6 a pair depending on quantity.  So this is only a test! 

When I ordered them, I was expecting to remove the coupler from the pocket and fabricate a new one from brass (or something).  It turns out they are too small to work in the tubing above, and there is no convenient next size down that I can find, so I had to look elsewhere.  It took me about 5 min. to realize that I should keep the pocket, and the truck bolster hole, which gives me something like this, after slicing off the sideframes:







Here's a size comparison to the McHenry:



The top photo shows the pocket 'right-side-up', but I decided that it would be more convenient to have the pocket flipped over, so I inverted the coupler in the box.  Next up is a test on an Athearn tank car.

[davefoxx]

MT 2004 does not work ?

victor

I can't speak for Gary, but I have had problems with existing boxes like the MT 2004 (or its attachment screw) fouling the axles of the adjacent wheelset.  There is a need for a much lower profile coupler box for cars with proper ride height, as well as a shorter box for installations on, say, an F-unit.

DFF

[GaryHinshaw]

The Athearn ethanol and LPG tankers provide a good challenge for ride height and body mounting.  Because of the screw-on bolster design, the only practical way to lower ride height is to use trucks with lower bolster cross members (e.g. BLMA).  Fortunately, these fit perfectly and look great.  However, the end platform is then slightly lower than the MT std. height, so either an underslung coupler, like the MT 2004, or something slimmer, like the FT Z scale, is needed.

Here is how I mounted the FT coupler:



The screw is a 1-72 x 1/8 mounted directly into the tank body (rather than the more flimsly end platform).  The resulting assembly is quite sturdy.  (These FT couplers are quite sturdy themselves.)





An overall shot:

[GaryHinshaw]

I agree with Dave's comment about 2004s.

[GaryHinshaw]

One more post, for now.  Here is a comparison of a few options:



Top is truck-mounted MT 1035 (not bad-looking), middle is FT, bottom is the stock, truck-mounted Accumate.  Here is a shot comparing the FT coupler height (right) to the stock MT:



[The MT 70T trucks are undersize for this car and tend to accentuate the high ride height.]  The FT's will mate fine with the MTs:



...and with themselves, of course:



So, I'm very happy with everything about these couplers except their price/availability.  I think it would be awesome if these were available as separate couplers with pockets.  Even better would be a pocket with a more flexible mounting system: something like 1) a hole through the pocket for typical box-car type mounts (though see DKS's clever approach in his review page), and 2) a ring, slot, or prongs behind the pocket that is level with the top of the pocket for other types of mounting (like tank cars & hoppers).  If the rear prongs were not needed, they could easily be sliced off.  As it is, I'm not falling hook, line, and sinker for the FTs, but it's so close to being an ideal choice...

Comments, alternatives, improvements, etc. welcome.
-gfh

[bbussey]

... The advantages of this approach (all true of Bryan's version) are: extreme strength; customizable pocket length (e.g., extended draft gear), and relatively low cost.  The additional advantage of my mod is a slight simplification: no need for the interior piece of tube, and no need to trim the set screw.  The disadvantages are: the rectangular tubing is not trivial to work with (unless you have the right tools); the Accumates & McHenrys are really big; these pockets wont work with MT's because there is no easy way to install the centering spring.

Looks great Gary!  One other update - the method can be adapted to MTL couplers by cutting out quarter circle wedges around the screw hole to clear the coupler centering pins.

The FT couplers look intriguing.  They might be worth exploring further.  Do they come with MTL-compatible trip pins?

[Craig Martyn]

Awesome work Gary!

[Mark5]

Very cool thread ...

the Accumates & McHenrys are really big; these pockets wont work with MT's because there is no easy way to install the centering spring.

Yeah, I kinda sorta can't get past the length of the McHenry. I can live with the Accumates as they seem smaller to my eye.

The brass rectangular tubing concept intrigues me - I like it!

Mark

[ednadolski]

Nice work Gary!   Thanks for posting this.    I have a few questions:

- The FT looks great with the Athearn tanker!  What is the longest car and smallest radius curve that you have tested the FT on?

- With the set screw (a) where did you get them from, and (b)  do you ever have any issue with them loosening up over time?   Maybe a small bit of thread locker could help with that.

- With the rectangular tubing, what's a good way to attach this to the car body?  Can it just be epoxied on in some cases?  Also, do you ever see any wheel clearance issues with this?  (Edit:  seems possible to grind away portions of the brass tubing if they have any issues with the wheels/axles.)


Craig -- it's good to see that you are monitoring this  


Ed

[David K. Smith]

Great work, Gary. I'm particularly excited that you found a very simple mounting approach (simple is always better). Congrats!

I am sorry I couldn't persuade Will to offer them separately. However, you've already shown how tricky this could be. If he had provided couplers with just pockets, you would not have had the chance to mount them the way you did, since the pockets probably would not have included the bolster. So, it worked out well that you did the beta testing; it might help lead the way to new products. Perhaps someday these will be offered separately, but I could not say when the someday might be.