I bought some Athearn 86 foot box cars a while back. Unfortunately it seems that the couplers droop down which causes them to unhook while in a freight train. This problem is even more pronounced when there is any kind of grade involved. Here is a link to the car in question http://www.athearn.com/Products/Default.aspx?ProdID=ATH1988. I do use a coupler height gauge to align the couplers on all rollingstock but the plastic tongue on which the coupler is mounted seems to make the couplers hand down. Has anybody else had the same problems and so which replacement couplers solved the problem.
I can only answer for myself, I have 4 of the early Athearns like that. I used Kadee couplers, but I also used some brass wire to make a U shaped piece that I mounted on the underfloor toward the end, drilled holes and AC’d the wire in after the installation was finished. That caused the long piece to rest on the brass wire and holds it up. Mine have been in use for several years and have not been a problem since the change.
Certainly someone may have a more sophisticated way.
I have a small fleet (9) of the Athearn 86’ box cars as at one time I was going to model an automotive plant. I use KD # 5 couplers in the Athearn box. These cars are long and if the metal weight is bowed it can flex the ends up or down. I also added weight to the cars to bring them up to NMRA recommended standards and added metal wheel sets. They ran great on my previous layout which was an around the walls layout with 42" main line radius. These cars also do not like big grade changes due to their length they tend to come uncoupled.
You might consider cutting center pin out of coupler box, then drill and tap through coupler box, through car floor and up into metal weight, then assemble the whole works with a #2-56 x 3/8" screw. With a Kadee coupler box cover (“ears” trimmed off) on the underside, you should be able to apply enough pressure to pull the coupler pockets back to the correct height without causing coupler bind.
I was having the same problem with my Walthers 89ft auto racks. They are extremely sensitive to dips and bulges, which I could never entirely get rid of. So I equipped them all with Kadee #118‘shelf’ couplers - even though they technically are not prototypical if viewed up close, they do an excellent job of keeping my auto rack trains together!
Walthers makes a swinging coupler box part that allows for much better operation of these cars. I forget the part number and am away from home. but a serach of the Walthers site or catalog may help. I’ve installed a couple of these and they are a neat and effective solution to the problem.
The Kadee #6 was the original coupler deisign for this car - superceded by the #46 (w. Kadee’s coupler box relplacing Athearn’s - (or #41 with Athearn’s friction fitting/ ‘snap-on’ cover).
These are “Discontinued Blue box” cars. Replacing Original trucks with kATO Roller bearing S-2 f33" freight trucks greatly improved rolling. I really like trucks with metal wheels & Delrin sideframes.
BODY MOUNT the couplers using #46’s-#5’s, first. THEN Transition your grade changes, second. They’re too abrupt for double-length cars, therefor ‘unhook’ (Laws of physics, old bean). You simply need to improve the ‘handshake’: “Transition” = gradual change - say 6"-12".
DROOP:(1) Body mount using Kadee 40 series with flat spring coupler boxes. (2) LOSING CARS: Transition changes in grade. (3) Improve the HANDSHAKE.
For any car over 50’ in length, I use the Kadee #46 long center shank coupler. Coupler body mounted long cars tend to swing out further on curves. Having a longer coupler on a long car will eliminate a derailment because if the car is equipped with a short coupler like the Kadee #5, it will swing out further and will end up pulling the car’s truck behind it off the track…chuck