Kadees and tight curves

rrgeorge has dealt with this problem and can probably answer your questions.

Dennis

First, let me say that I have never tried body mounted Kadee couplers on any curves under 072, which is the minimum curve on our layout. Now, in my opinion, even with shorter freight cars, say 40 footers, I think you are going to have problems on any curves tighter than, say 054, with body mounted Kadee couplers. I would certainly try some experiments on your layout, however.

Some years back, Atlas had the "Adjust-A-Coupler" concept, with the coupler mounted to an adjustable bracket on the freight car truck, which would allow operation on much tighter curves. The concept was very good, however the Atlas version of the "Kadee style" couplers were crap, and they broke or disassembled themselves.

Lots of factors are involved with body mounting.

First, S-curves of any kind must be avoided. Use numbered switches (#4 or #5 or Ross/Gargraves regular 11 degree) instead of O72 or O54 etc. for passing siding situations and yard ladders.

As far as diameters, O42 curves and 40 foot freight cars are OK in my experience. 50 footers will almost touch corners on O42. 50 footers should be OK on O54 and maybe O48.

Things are different when pushing cars in reverse. Wider radius is needed for switching moves (which is the whole purpose of using the Kadees for most of us in the first place!). 50 footer corners will definitely touch on O42 and probably O48 when reversing.

The O36 will take some experimenting. I'm guessing the 40 footers would be OK (barely) when pulling, but not pushing. I've never tried the long shank couplers, but they would have to help on tight curves. You would lose the close coupled effect though which is another neat feature of using Kadees.

I'd equip a few cars with the Kadees and experiment on your curves. That's the only way to be sure. A slight unevenness in diameter might make a big difference in spots with the tight curves. I had a few spots where my O42 had problems, and I had to readjust the track.

Remember too that there are lots of creative ways to work around the problems. You could make some 50' transition cars with Kadees at only one end to create blocks of the longer cars with regular knuckle couplers in the middle. 

Or... as you mention, you could use truck mounting for the longest cars. It's not a good idea though to couple body mounted cars and truck mounted coupler cars together, particularly on tight curves.

Your tight curves will create some limitations, but there is no reason why you cannot have at least some Kadee equipped cars - at least enough for some nice switching operations where the Kadees will be at their best and will be well worth the trouble.

Jim

Yeah - you must experiment. 036 frame mount? Ouch. But, buy a few (not a bunch) and get some answers. 

Kadee used to offer some sort of "flexible pocket", in spirit - I think - much like Lionel's new "kinetic" pilot/coupler: the pocket on the frame would pivot when needed, and then return to center on straights or big curves.

Or so I recall.

I'm using Kadee body mount couplers on my O36 Atlas track layout. My layout is level, no S-curves, and the longest car I run is 36 foot. A 40 foot car is very doable on my layout, just haven't done it yet. 

I had the same problem, but have only completed 2-3 Kadee conversions.  I opened up the mounting box a little by removing some of the plastic on the sides so the bar had more room to move side to side.  Worked for me.

Ron H & Co. addressed the passenger car truck mounted coupler issue successfully:

https://ogrforum.com/t...close-coupled-kadees

Thanks so much to all for the inspiration.

My wallet hurts,but I bought 3 40' boxcars (2 MTH, 1 Atlas) and 1 40' reefer (Atlas) along with 2 pairs of kadee 805s and 2 pairs of kadee 746s.

That should give me enough to get experimenting!

On a 40 or 50 foot box/ 054 minimum....any less and the cars will contact each other on a curve when you back up !!

036 in your jargon is only 18 inch radius.   that is pretty tight.     I have moved 40ft cars on 24 inch radius which is equivalent to 048 without issues.   

Body mount couplers do contribute to better tracking if you have free rolling wheels.    All the forces are on the bodies and the trucks guide the bodies.   With Truck mounts, the sideways forces on curves are on the trucks.   

One way to  use body mount is to not use the coupler box.    Fill the slot in the coupler shank with 1/8 styrene.    Figure out how far under the body you want to mount the coupler, and measure that distance on the shank.    Drill a clearance hole for a 2-56 screw at that point in the styrene (I think #46 drill).    Then drill a #50 hole in the body where you want to mount the coupler and tap the body hole for a 2-56 screw.    Mount the coupler with a 2-56 screw and a washer underneath to keep it level.    Since the styrene filler is totally surrounded by metal and held in by the washer and body, it cannot go anywhere.    This type of mounting gives  you complete swing on the coupler similar to radial couplers on streetcars.    If you want to do more work, you can use the small hole on the back of shank and feed a spring through it and over a second screw on the body to make the coupler center.    

the best bet is to experiement with some temporary track and then decide how you need to mount the couplers to make them work.

Remember real rail road couplers do not center automatically sometimes  you see a brake raise his foot up and shove one toward the center to make a joint.

Mike, I recently started to dabble with the "3-rail scale" concept by installing Kadees on a few Weaver scale-sized 40' boxcars, and fixing the pilots and adding Kadees to an MTH SW1 switcher.  At the moment, I only have a tiny 4' X 6' layout in my basement.  It was constructed with MTH RealTrax and utilizes O-42 curves.

I shot two quick videos with my iPhone last evening--one with the train moving forward (engine pulling), and one with the train backing up (engine pushing).  This will give you a visual example of what some of the others have been mentioning in this thread.

You can see for yourself the proximity of the car corners/edges as the train moves in each direction.  These cars are fitted with standard length Kadee coupler shanks with no alterations to the boxes.   You'll also notice that the last boxcar is a "transition" car...Kadee coupler on one end and a traditional "lobster claw" on the other end.  I apologize in advance for the video quality!

FORWARD Move:

REVERSE Move:

The good news is that despite the pretty tight squeeze on the reverse move, I can still get by with 40' cars on O-42.  I have run this train in both directions for extended periods of time and have had zero derailments!  I can't speak for O-36 (I don't own any), or cars longer than 40 scale feet as I haven't converted any of those yet.

Hope this helps a little bit.  Good luck...and keep us posted on your progress!

Joe - those videos are great! Thanks so much for posting!

I think the first of my boxcars (40') was delivered today - I will see when I get home - Kadees should come in this week too, then it's time to experiment! 

The 036 may end up being tight, but looks like i'll get away with 048 just fine!

There's a good rule of thumb to follow with body-mounted couplers. Bare minimum radius for MOST cars is 3 times the bolster-to-bolster distance (car wheelbase). Better is 3.5 times the wheelbase and optimum is 4 times the wheelbase or larger. Remember, the O-number -- i.e. O-72 is the diameter, so the radius is half that or 36 inches. Passenger cars and other cars where the trucks are set in farther (look for those long 3-rail coupler bars) require broader curves due to the "swing-out" of the car ends in curves.

Also, with body-mounted couplers, you need to put more focus on car placement. A short car should not be coupled to a long car with extra overhang (40-foot HiCube to an 86-foot HiCube for example) unless the curves are very broad (72" radius/O-144 and above for the HiCube example). Also, factor in how much swing-out you have on your locomotive. Surprisingly there isn't as much as you might think because the trucks are very close to the ends, though 4-axle diesels would fare better on tight curves. Another thing you should do with sharper (36" Radius/O-72) curves is place the shorter cars up front with the longer cars toward the rear. This puts more flanges per foot up front to reduce the risk of string-lining on longer trains. The catch is that the cars need to have enough weight (in some cases over-weighting the smaller cars).

Bottom line is you need to be very careful with your equipment selection if you're going to go with body-mounted couplers. CNJ1601's example is a perfect situation -- 40-foot cars (approximately 7-inches between bolsters), a short locomotive and a caboose (like the judicious use of a transition car).

Nice videos

Forgot to mention that Laidoffsick has put out 5 videos specific to converting to Kadee couplers - I just watched the first one. 

Go to YouTube and search Laidoffsick.

Doug uses the Kadee 740 and then purchased / then makes he shims needed. My plan is to watch all 5 then start to convert a couple of Atlas cars.

Kevin

Kevin, I couldn't agree more regarding Doug's videos.  They are VERY informative.  That's exactly how I learned to do my conversions...right down to the use of the Kadee 740's!!

I am glad I joined this forum it is very informative, thanks