Kadee couplers disconnect on grade.

I'd check the "vertical curve" at the bottom of the grade. If it's too sharp, the end of the car is going to dip pretty far. Also watch the vertical curve at the top of the grade as well. Unfortunately, some of the things we get away with using hi-rail couplers can come back to bite us when we switch to Kadees (I know this from a lot of personal experience).

Thanks Matt.  

Just curious if you checked the Kadee couplers with the Kadee gauge after you installed them? Sometimes shims are needed. I did one of the MTH 19th century passenger cars and one side was spot on and the other side needed a slight shim. Drove me crazy but I could not figure out why. 

Bad is too strong a word.    As matt says above could be either.   

When you install Kadees, check them on a flat straight to see if they are all at the same height.     Compare car to car, or use a Kadee gauge.

Bumps and humps in the track can cause this or too quick a transition into a grade.   

The length of the cars also contributes to how this stuff affects them.

@Tom Tee posted:

Flat and level are two distinct characteristics.

I cracked a smile when I read this.   Very true, and sometimes a hard thing to grasp.

So it could be a combination of sloppy track work and sloppy kadee install.  I think either way that points to me as the problem.

Well, I can tell you from experience that PROPER, i.e. to the Kadee height gauge, hight of Kadee couplers on long passengers cars, is critical! Then, add that "dip in the track", and it would be pretty difficult to keep this long passenger cars coupled together.

When I started running 2-rail equipment at the club (MTH scale-wheeled locomotives and various rolling stock), I quickly found out where our track work had become compromised from years of thermal expansion/contraction and coastal moisture tweaking our benchwork. While it didn't have an impact on hi-rail equipment, my six-axle diesels would find them and we'd fix the problems. Made things better all around, but we're looking at a major reworking of a large curve by the farm on both mainlines because the 20-plus years have taken their toll on the Gargraves flex (we're looking at replacing it with Atlas O-99 and O-108 fixed curves). The benchwork decks are all 1/2" plywood so our vertical curves are well eased and our grades are 1.5% on the mains and 2% on the branch.

I'm going to start reworking the couplers since that is the easiest.  

I seem to recall someone sold thin shims.  Was that Laid off sick?

Thanks

Ron

@Ron045 posted:

I'm going to start reworking the couplers since that is the easiest.  

I seem to recall someone sold thin shims.  Was that Laid off sick?

Thanks

Ron

You can purchase strips of styrene, 1/2" wide, in all sorts of thickness from Evergreen. My local hobby shop ordered whatever I needed.

Scale City Designs  sells premade shims in various thickness they have the same foot print as a Kadee coupler.  I bought a bunch of them the last time I ordered. Nice to have them handy just like all the different Kadee couplers.

In one of your photos it also appears one of the coupler pockets 'could' also give you some grief.    Russ

Ron, I think Micro Mark also sells shims.

Andy

Ron,

Curious, is it always the same cars and ends?

@BobbyD posted:

Ron,

Curious, us it always the same cars and ends?

While I have not done official testing of all scenarios, it does seem to be two cars that are problematic.

One of the cars I did reverse and the issue stays consistent at the same end.p

Ron

@Ron045 posted:

While I have not done official testing of all scenarios, it does seem to be two cars that are problematic.

One of the cars I did reverse and the issue stays consistent at the same end.p

Ron

Interesting. Maybe mount or coupler itself?

Scale City Designs  (http://www.scalecitydesigns.com/)  makes and sells shims that are exactly the same size as the Kadee box in 4-5 different thicknesses, thickest being 1/16 inch.

You should settle on a coupler heigtht, and then insure that all cars couplers on both ends  are that height.    The simplest thing to do is buy a Kadee coupler gauge and use it to set all cars at that height.    If  you choose some other height, you should make  your own gauge to be able to consistently check and measure if couplers are mounted at a correct height.

I think you have been advised to check for dips and bumps and too quick transition from level to grade or grade to level.

With Kadees, I am going to guess the coupler head is about 3/16 inch high.    I think 3 rail couplers are 1/2 inch in height.    So with a kadee if there is a track condition that causes one car to rise or drop 3/16 inch vs another, they will uncouple.

You can get away with some differences in mounting height, but not nearly as much as with 3 rail couplers.

The long shank 74X Kadees can be a bit of a challenge. The shims have to be straight and level lengthwise as the extended length shank makes a nice teeter totter on uneven track. I also tend to spend a bit of extra time eyeballing the knuckle height against 805s like your pic. If you don’t use the actual 740 knuckle as the height reference you’ll get a pesky height delta like you’re seeing. 

Any solution Ron?

@BobbyD posted:

Any solution Ron?

No time yet BobbyD.  Was finishing a repaint for a friend and my BlueRail engine.  Winterized the camper this weekend.  

Wanted a mindless task yesterday afternoon, so I ballasted some track.

Maybe this week.

Ron