I have a P2K E7 A & B unit. They are uncoupling themselves coming off a downhill curve and under load. So, since both have the crappy P2K couplers, I replaced the knuckles with Kadee #5’s, but kept the P2K box and arm to the body. Same problem.
Turns out, after carefully watching them, the coupler ARM is raising up under load!!! A lot. It then disengages from the other car’s coupler which doesn’t raise up all that much. Tried shimming the arm, but no matter which thickness I use, .011 , .065, .040, the arm no longer would have a spring return. The spring is really light.
I have other P2Ks and they don’t exhibit the problem. As for that portion of the track where it occurs, no other engine (14) or car (125+) has a problem in that area.
Any one else have this problem? If so, how did you fix it?
Thanks for your help. Ken
It sounds like there is some vertical alignment issues with your track. If you can, lift up the track and sand the transition area (where the downhill slope begins).
Leaving or entering an Incline vertically misaligns knuckle couplers. Main correction is adding a transitional slope when approaching and leaving the inclined track.
P2K’s knuckle couplers have their own problems - even when level.
There may also be too much play in the couplers. Replacing with Kadees is always the right first step. Maybe you need a very thin shim inside the draft gear box. I’ve never done this myself, but try cutting a piece of aluminum foil to the shape of the box and putting it in. It should cut the vertical play and reduce the problem.
If you do have a “vertical kink” in your track, though, that’s something that will need to be fixed.
Ken,
I would suggest that you try the Kadee close coupling conversion. It not only makes the
A/B set look much better, but it makes them almost impossible to uncouple vertically. The
couplers end up under the diaphrams. I posted a topic about it some time ago… I’ll see if I
can find it. I also agree with what the others have said about the transition into the grade.
I learned the hard way on my last layout that no transition leads to uncoupling. Good luck. Dave
EDIT: If you look at my Photobucket album on page two you will see the loco after
the conversion. Dave
Yeah, that was my first guess too. But the downhill ends about 2 feet before the [problem area, but still within the curve). The track transistion from level to hill is quite gentle. I think the curve + the total # of cars + the # of cars still coming down the hill puts a lot of load on the P2K’s couplers & arms. Actually, I can recreate the problem on straight track. Under a similar heavy car load, you can see the coupler (which has a little vertical play) and the coupler arm (which has a LOT more play) rise up about 3/4 of the way above the first trailing car’s coupler (which doesn’t move hardly at all). Are there replacement coupler arms?
Thanks for the reply. Ken
There may also be too much play in the couplers. Replacing with Kadees is always the right first step. Maybe you need a very thin shim inside the draft gear box. I’ve never done this myself, but try cutting a piece of aluminum foil to the shape of the box and putting it in. It should cut the vertical play and reduce the problem.
Good tip. I’ll have to give that a try. Thanks. Ken
Ken,
I would suggest that you try the Kadee close coupling conversion. It not only makes the
A/B set look much better, but it makes them almost impossible to uncouple vertically. The
couplers end up under the diaphrams. I posted a topic about it some time ago… I’ll see if I
can find it. I also agree with what the others have said about the transition into the grade.
I learned the hard way on my last layout that no transition leads to uncoupling. Good luck. Dave
Good pics. I like the look. That’s the 455, right? My Walther’s cat. doesn’t describe it very well. Does it come with a replacement coupler arm of some kind?
Ken,
Yep… It’s the #455. The kit comes with the replacement drawbars and you will need to do
some drilling and tapping. But, I’ll be the first to say that it was well worth the effort.
The kit also comes with #5’s.
You may already have these, but if you don’t, get a pin vise and a tap holder. You will only have
to drill and tap plastic, so it fairly simple. In the picture below you can see what I used( although
I only used one of the drill and tap sizes). Good luck, Dave
I don’t have the E7’s so I’m not really qualified to answer, but, If the ‘arms’ are the problem, why not remove them? Kadee recomments #23’s and #26 for the pilot.
E7’s can operate with ‘Body Mounting’.
I do have P2K E-8’s and E-6’s with Body mounted couplers.
This is exactly what I do. I don’t run on any radius under 24", so body mounting and replacing the swing arms could cause a problem on any smaller radius. I don’t know what the min radius is for the E units w/ the stock cofiguration.
Posted: Today, 00:21:00
Although the prototypical close coupling looks fantastic and rarely would uncouple under normal conditions, not allowing enough clearance between knuckle/ diaphram makes uncoupling almost impossible by 0-5-0. I have a problem w/ Walthers heavyweights that do this. Cutting some material off the bottom of the diaphram or changing to #58s was the only solution. If there was a derailment, the cars couldn’t be separated. Accidental bumping or a persom lifting one car would lift the entire string of cars and coupler damage is is possible.
When placing #450s on Stewarts and using American Limited diaphrams, I always allowed this clearance when placing the diaphram. Sometimes even trimming the bottom of the contact plate. This should also be considered w/ the “E” units as well.
Bob,
You are 100% correct about it being difficult to uncouple the E units with the “skyhook”
method[:)]. But, I rarely uncouple the A anb B units from each other. So this is not a
problem for me. I can see where it could(would) be a problem with a string of
passenger cars… especially in a derailment.
As for body mounting, my BLI E8 has body mounted couplers… why Life-Like decided
to go with the swing arm… well I don’t know. Maybe it was for a smaller radius. But the
close coupling conversion does shorten the swing arms considerably… and is a lot less
stress inducing (for me anyway) than body mounting the couplers[:)]. Good luck, Dave
