I'm just converting to DCC and I run LONG trains. The DCC locos that I have recently added to the fleet all come with plastic Kadee-type couplers. However, my long trains sometimes cause these plastic couplers to fail. My question is, Would it be an issue to replace these with metal Kadee couplers? I'm wondering about possible electrical shorting issues.. Thanks for any advice..
3rd rail I'm just converting to DCC and I run LONG trains. The DCC locos that I have recently added to the fleet all come with plastic Kadee-type couplers. However, my long trains sometimes cause these plastic couplers to fail. My question is, Would it be an issue to replace these with metal Kadee couplers? I'm wondering about possible electrical shorting issues.. Thanks for any advice..
It should be fine. What locos do you want to convert? Did you look at the Kadee Conversion Page? https://kadee.com/conv/hocc.htm
I use Kadee #5s in just about everything, but occasionally you can have trouble with some locomotives, like some brass locos or Bowser Steam kits, say.
Gary
If you are concerned about using metal couplers, just use Kadee plastic couplers.
What makes the Kadee coupler so reliable is the use of a metal spring hinge as opposed to a plastic hinge strip which often fails while running trains of any length.
Rich
Alton Junction
Look carefully at how your locomotive coupler mount works. If it is metal with metal screw but platic coupler box with internal sleeve you are fine. If you have metal to metal contact in a hot frame locomotive, be careful. Some BLI steam and diesel locomotives have a hot frame (as indicated by a plastic insert above the coupler and verfied by multivolt meter), my BLI e7s and 4-6-2 have hot frames. The 4-6-2 had a plastic coupler. When I switched to Sergent Couplers I had to cut a piece of .010" styrene to insulate the coupler and use a plastic screw (I think thats how I did it).
The the only way to tell if you have an issue is to take a multivolt meter and perform a coninutity check between coupler box screw and each wheel. As long as you have an open circuit, no issues. If you do you will need to figure out how to insulate (styrene, plastic screws, etc).
Plastic couplers that fil with a heavy train sound an awful lot like the junk ones that came on Proto 2000 locos (pre Walthers, when they were plastic, not the new Prot-Max metal ones). I had some that got jammed open and you couldn;t close them. EVERY non-Kadee coupler in my locos and cars has been repalced with a genuine Kadee one and I've never had any issue. The original is still the best in my experience. At the club, one highlight is when we run a 135 car coal train. Those coal hoppers are, in many cases, actually heavier than NMRA recommended weight for the size car. While it ties up a lot of track and drives the dispatcher nuts, one thing that does NOT happen is any coupler problems. All Kadee.
Kadee has enough variations that you can fit them in most anything ever made. More modern locos, especially those that came with some other knuckle coupler, are pretty good with respect to height and are rather easy to replace.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
If you're running in DCC, having metal couplers won't affect anything electrically. I can run any of my engines, all of which use metal coupers, together in any combination and it works fine.
Before DCC, most HO engines were designed to have motors that picked up power from the metal frame - that is, the wheels on one side of the engine transferred electricity to the frame, and the motor picked up electricity from the frame. In that situation, if you ran two engines together that both had metal couplers connected to the frame, it was possible to get a short circuit.
However, in DCC, the motor has to be completely isolated from the frame. Almost all engines made today come that way, an exception being Athearn "blue box" engines still using their old design. On those engines, you have to remove the motor and isolate it (not all that hard to do). Since the frame isn't part of the electrical circuit, attaching metal couplers to it doesn't affect anything.
I don't think you have to worry. There's a video out there of Kadee couplers holding pounds off them. That's way more than your loco can pull.Some people avoid all metal couplers and draft boxes because the engine serves as a conductive frame. If you hook it to another engine you could have problems. This is especially true of older locos, older brass, and 2 rail O scale.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
wjstix If you're running in DCC, having metal couplers won't affect anything electrically. I can run any of my engines, all of which use metal coupers, together in any combination and it works fine. Before DCC, most HO engines were designed to have motors that picked up power from the metal frame - that is, the wheels on one side of the engine transferred electricity to the frame, and the motor picked up electricity from the frame. In that situation, if you ran two engines together that both had metal couplers connected to the frame, it was possible to get a short circuit. However, in DCC, the motor has to be completely isolated from the frame. Almost all engines made today come that way, an exception being Athearn "blue box" engines still using their old design. On those engines, you have to remove the motor and isolate it (not all that hard to do). Since the frame isn't part of the electrical circuit, attaching metal couplers to it doesn't affect anything.
Simply isolating the motor from the frame does not prevent the shorting issue on locomotives that have it - the frame would still be picking up curent from one rail.
Athearn BB locos have a hot frame, as do early P2K locos which were exact copied of Athearn but with bigger motors, hoever most P2K locos have a plastic draft gear box which insulates the coupler. I replaced the wonky P2K plastic couples with Kadee #5's in all 4 of my P2K Geeps and run pairs of them back to front all the time with no problems - this is where you would have a problem if there is a conductive path throught he frame and couplers, since when put on the track front to back, one has the frame connected to the left rail and one to the right rail. Both facing forward, even on old Athearn BB locos where the coupler was in a metal gear box would not be a problem since both frames would be connected to the same rail. Either use the plstic shank Kadee couplers there, or grind down the cast on coupler pad so you can attach a Kadee in its own plastic gear box - or body mount it. The plastic shank Kadees might as well be the metal ones, they are nearly as strong, whatever sort of plastic they use in there isn't fragile, and it's just the shank of the coupler, the knuckle and knuckle spring is still all metal like regular Kadees.
rrinkerEither use the plstic shank Kadee couplers there, or grind down the cast on coupler pad so you can attach a Kadee in its own plastic gear box - or body mount it.
I have a few ancient BB locos and I did just that. With plastic draft gear boxes, I can use metal Kadees with no problems. These old engines are just sound dummies now, but there is something about still seeing engines from my teenage years in some sort of service on my layout.
It takes an iron man to play with a toy iron horse.
While everyone else was dancing around the answer, Randy came out and said it plainly. Plastic shank couplers are generally only needed with hot frame loco's which typically were/are old Athearn blue box engines where the frame came into contact with the metal coupler due to the mounting method used; which BTW, I always thought was a horrible mounting system - that plastic clip seemed like a cludge anway.
Rio Grande. The Action Road - Focus 1977-1983
The ones on the car kits are worse though, they seem to always fall off. That's why I bought the A-Line jig that centers over the mounting post so you can drill them out for a 2-56 screw and be done with it. At least with the whisker couplers you don't need 4 hands to install them, one holding the car, one holding the coupler, one holding the centering spring and one trying to snap the cover on.
Quite apart from "live" frame locomotives, metal KDs can still be an issue with DCC if you have some older rolling stock (not older prototype - I mean actually old models) with metal frames, such as Ulrich, the old Model Die Casting, and some other long-gone brands. Some of the old metal trucks (metal wheels AND axles) sometimes had wheels that were insulated only on one side (often marked with a spot of brownish varnish on the end of the axle) -- you would orient the insulated sides for both trucks to the same side, but even so it was possible to have an interaction of metal coupler, coupler screw into the frame, trucks picking up current into the frame, and passing it along to another similar car down the train. A darned hard short to trace I can tell you!
I have to think the number of guys with DCC and these very old models are few and far between. But it can happen. Today perhaps brass freight cars would be the more likely source of issues but only if you have those old fashioned trucks that are insulated only on one wheel. Plastic axles have addressed that for most brands.
Dave Nelson
Thanks for all the input guys. Yes, I was concerned with multiple unit consists. I think I have my answer.
Todd
Athearn BB locos ALWAYS have the frame as part of the electrical circuit used for power pickup. Isolating the motor in no way changes that fact.
For example, if one loco is pointing 'forward' one of the rails is connected to the frame......another loco on the same track pointing 'reverse' will have the othe rail connected to the frame. If the frames touch, the rails will have a direct short applied.
There is no EASY way to change this configuration, because the Athearn power trucks apply power from one rail to the pivot point where the truck connects to the frame. That pivot point would need to be completely insulated from the frame AND wires connected directly to the truck frame to isolate the frame from the rails.
rrinker The ones on the car kits are worse though, they seem to always fall off. That's why I bought the A-Line jig that centers over the mounting post so you can drill them out for a 2-56 screw and be done with it. At least with the whisker couplers you don't need 4 hands to install them, one holding the car, one holding the coupler, one holding the centering spring and one trying to snap the cover on. --Randy
Generally I haven't had much trouble with the clips falling off and so far have never needed to resort to drilling and tapping for crew mount. If a clip seem like it might be prone to not be tight, I'll give it a gentle squeeze with needle nose plyers to make sure they are clipped on securely.
I still have some Athearn blue box rolling stock, but most of it I have sold off and about all that is left are a bunch of 86' auto box cars since I've found better alternatives to the vast majority of my other rolling stock. For the 86' box cars, since the couplers come out low and I don't care for the Athearn swing pocket, Harry recommended the Details West part.
I've sometimes put a little Walthers Goo on the sides of the Athearn coupler boxes to hold them in place.
I guess, now that I think of it, the old Athearn BB frames would indeed still be getting current even when the motor is isolated from the frame. Only BB engines I have on the layout are some F7s that run in an A-A set, connected by a plastic drawbar, so it's not really an issue between the two of them, and I don't think I've ever run them in a consist with anything else, so maybe it's just a problem that's never come up for me.