Coupler height

User avatar
Rob M
Posts: 613
Joined: Mon Jan 30, 2012 12:35 pm
Location: Northern Wisconsin

Coupler height

Post by Rob M »

I'm a little confused about proper coupler height and how much tolerance is acceptable. The Kadee #714 is 1/8" thick and the knuckle looks like it is centered height-wise. The NMRA standards say it should be .281” to the center of the knuckle. Elmer’s coupler height gauge puts it at .2685”

Image
Image

User avatar
ConducTTor
Site Admin
Posts: 8823
Joined: Sat May 23, 2009 4:52 pm
Location: Atlanta GA USA
Contact:

Re: Coupler height

Post by ConducTTor »

Hm. I'm a little confused as well.
My website: https://www.ttnut.com
It's the website you're already on. But if you want to be even more on it, click the link.

areibel
Posts: 1798
Joined: Fri Jun 12, 2009 10:12 am
Location: Cambridge Springs PA

Re: Coupler height

Post by areibel »

This is right up Chris Happe's alley, I'll send him an email and ask him for clarification.
I do see one possibility- on the NMRA's coupler page (http://www.nmra.org/standards/sandrp/pd ... 010.07.pdf)
it says the centerline is .281 but there's a tolerance of .013 plus or minus. And there's something in the remarks column about a "1/4 Rule: .0225", whatever that means!

User avatar
Rob M
Posts: 613
Joined: Mon Jan 30, 2012 12:35 pm
Location: Northern Wisconsin

Re: Coupler height

Post by Rob M »

Well crud, I didn't even see the tolerances listed there :doh: . I just found the size I was looking for and closed the window.

Mostly I'm curious what coupler height everyone uses so I can shoot for that. Then a variance of +/- .013 would be within specs. If I go by Elmer's guage and end up .01 low it would be out of nmra specs.

areibel
Posts: 1798
Joined: Fri Jun 12, 2009 10:12 am
Location: Cambridge Springs PA

Re: Coupler height

Post by areibel »

I'll have to see if I can find my coupler gauge and see what it measures out at, but right now my basement looks like a tornado went through! The other thought i have is if they give that tolerance but you're using Micro Trains couplers how would that affect it? I have some rolling stock with 714's mounted, but I've pretty much switched over to 1025's for anything new. They do couple together fine, but maybe I've just been lucky!

User avatar
Rob M
Posts: 613
Joined: Mon Jan 30, 2012 12:35 pm
Location: Northern Wisconsin

Re: Coupler height

Post by Rob M »

The 1025's (left) are .095" high so they would be .015" higher to the center when under-mounted.

Image

areibel
Posts: 1798
Joined: Fri Jun 12, 2009 10:12 am
Location: Cambridge Springs PA

Re: Coupler height

Post by areibel »

I wonder if that's where the difference comes in? I'd have to ask Elmer to find out, but if he made two different height gauges, one for 714's and one for 1025's? or if there's one, from the drawing you posted if it's up .015 that would put it almost dead on (C/L) for 1025's, and the 714's would be within tolerance?

User avatar
Rob M
Posts: 613
Joined: Mon Jan 30, 2012 12:35 pm
Location: Northern Wisconsin

Re: Coupler height

Post by Rob M »

It says it's made for the 714's on his catalog page. No mention of one for the 1025's
http://www.ttscale.com/catalog/w-catalog.html

railtwister
Posts: 723
Joined: Sun Oct 04, 2009 8:39 am
Location: Oakland Park (Ft. Lauderdale), FL, USA

Re: Coupler height

Post by railtwister »

Hi Rob,

I'd say stick with NMRA lacking any other info. Also, its usually easier to add a thin shim if the couplers a bit too high than it is to raise a coupler whose mount is too low (I don't like putting washers on the trucks because that raises everything, not just the couplers!

The couplers I'm using are the MTL 1025 N scale couplers, on the premise that they are a bit too big for N scale, so they should look about right for TT. I forget what height I've been using, I'll have to check. For my other scales, I have made my own height gauge, it's pretty easy once you have the specs. However, it's not like I have too many cars to change if I see something I like better!

Bill in FL

Bill Dixon
Posts: 1373
Joined: Mon Mar 15, 2010 10:57 pm
Location: North Vancouver, B.C.

Re: Coupler height

Post by Bill Dixon »

Almost all knuckle couplers are too large for their scale.

Kadee HO scale couplers are the correct size for S-Scale.
Kadee HOn3 couplers are the correct size for HO.
MicroTrains Z-Scale couplers are the correct size for N-Scale.

That makes the MicroTrains N-Scale couplers the right size for TT-Scale.

Most modelers do not worry about the over sized couplers as their larger size allows for more variation in track work.
Those who use the smaller correct size couplers on their layouts tend to be more careful in their track work as if they don't they have more unwanted uncouplings.

Bill Dixon
TT-Tracks
North Vancouver, BC
Regards
Bill Dixon
TT-Tracks
North Vancouver, BC

Post Reply

Return to “General Discussion”