Using atlas electrocouplers with PS2 conversion

Try it and see...what's the worst that could happen?

Please let us know what you find.

I guess only one of 3 things could happen...

1: push the button and nothing happens (the board doesnt have enough power to open it)

2: nuke the coil in the coupler (board puts out too much power).

3: it works

If I had to guess, 1 and 3 are probably the only realistic options, so I guess the worst that could happen is that nothing happens. Maybe I'll pop a shell on a factory wired loco and test the coupler out. Its going to be a little while before this one is far enough along to try it out.

Measure the coil resistance of the Atlas Coupler.  I think the MTH is around 2.4 ohms.  The board puts out a pretty short pulse at high voltage.  Would be interested in knowing what the resistance is and if it works.  G

Atlas uses TMCC so the couplers would be consistent with the TMCC specifications.  I'm not sure, but doesn't TMCC use 12 volts?  Also, correct me if I'm wrong, MTH uses 5 volts.

So your problem would be pulse width AND voltage.

Jan

The SAW board uses the Lionel style couplers, and they are a higher voltage but a lower current than the MTH couplers.  I have tried to use Lionel couplers several times on PS/2 conversions, however they have never worked.  IMO, you'll have to change the coupler.

Boilermaker my experience is that the Atlas electrocouplers are about 7-8 ohms - similar to proto 1 couplers.  I have been replacing my Atlas electrocouplers with MTH proto 1 couplers as they break.  Also you have a choice of long or short length that can be used to pull engines or engine and cars close together.  I have had no failures of new Lionel couplers so am not sure if they have changed resistance or not.  IMHO the MTH couplers work better then other to uncouple with a load on the knuckle.

 I have an Atlas two rail version that uses their two rail couplers and a MTH board. It works fine after several years. Different voltage on their two rail ones???

I dont have the best multimeter, but I get a reading of 7.5 Ohms, and 2.3 for the MTH ones in the kit.

So I guess its not going to work.

Bruce, I'd be curious to see what your conversion adapter looks like.

Thanks.

Sheldon no conversion - all the electrocouplers are attached with the same t bar spring system and have been interchangeable so far for Lionel MTH and Atlas.

Hmmm, ok. This one doesnt have Tbars. It has a tab on the end of the truck, and the coupler has a box that screws into it.

Can you post a picture?

THe MTH coupler has about 22VDC available, but the FET probably has a very short duration, so I am not sure what the effective voltage the coupler sees.  Hence the lower coupler resistance.  Placing a higher ohm coupler in place will see less current (magnetic force) from the PS-2 pulse and therefore doesn't trip reliably or at all.

You can always give it a try and you may get lucky.  G

Here's the coupler attachment. The screw on the left attaches it to the truck. The one on the right holds the articulation joint together, Inside the box is a little spring that centers the coupler.

I'm going to try hooking it up to a factory install board and see if it works (i.e. pop a shell of an MTH engine). Maybe I'll get lucky, if not, then I'll likely just leave these locked shut and move on. Its not the end of the world to get these working, but it would be nice.

I don't think luck is going to enter into the picture, this has never worked for me.  The PS/1 and Lionel couplers seem to be compatible, but PS/2 electronics and couplers are unique and not compatible. 

Check the thread I started several months ago about Pulmor motors.  There's some info on electromagnetic couplers that I got from MTH.

Note that PS2 demands a coupler that does not have either terminal of its coil grounded.  If you don't honor this demand, you'll damage te PS2 board.

Thus, the old Lionel electromagnetic couplers cannot be driven from the PS2 board.  I used a Radio-Shack relay so I could use the Lionel couplers in my PS-2 #736 Berkshire, rather than extensive rework to hold an MTH coupler.

If you take the center screw off, what does the coupler end look like?  Can you mount the short version of the MTH coupler to your linkage?  G

That issue doesn't apply to PS/1 or Lionel electrocouplers from command locomotives, they're totally isolated.  The only situation that comes into play with is trying to use the old PW coil couplers with the MTH PS/2 boards.

The MTH one wont fit without a little bit of messing around. Its too wide to fit in the box and the hole is obviously not the same size. Getting the MTH one to the same profile would be impossible, as you would get into the hole in the coupler, but it looks like the sides of the coupler could be ground down so that it fits in the box, and then the hole in the box could be enlarged and tapped to take a bigger screw (the MTH hole is 3/16, so I should be able to find a machine screw that fits). I'd lose the articulation in the box, I dont know what that would do to the minimum radius of the engine, but its only 16" long and I'm running O54 minimum (bit with 21" cars its probably going to only do 072), I think it would work. The other option is to cut into the sides of the box, and still drill out the screw hole. It would have no centering effect, but the articulation would work. My guess is that the coupler is easier to get then the attachment box, so I'd rather try messing up the coupler first, and then only cutting the box if I had no other option.

I have to pay the MTH parts booth a visit anyways for a smoke unit, so maybe I'll pick up a pair of shorty couplers to mess around with and see if I can make it work.

That's what we call non-standard!  I wonder what possessed them to do that?

I wonder if you could make an adapter plate, rather than hacking up the coupler?

I think the adapter would be hacking up the coupler box, kind of the way you can hack the sides of a Kadee box open for extra swing. Thankfully, the shank on both is the same height, so the height wont change, assuming I can get them to go together.

I ought to see if I can get an extra box from atlas for experimentation purposes. Why they did it this way? I have no idea. It sounds like some of their later releases use the standard T-bar connection, but the dash 8 was their first O gauge diesel, so it seems like lots of stuff is "non standard".

Thanks for the brainstorming session guys... with enough engineers, sooner or later we'll always figure it out.

At the time the Coupler pictured was call an articulated coupler, allowing for tighter curves.  Also note the fixed pilots on the SW models.  Note the two pieces.  The coupler does flex in the middle.   I did some fabrication and adapted the majority of the coupler to a fixed mounting on my Rich Yoder 44 tonner. Using some of the Rich Yoder mounting system I was able to get them to be self-centering. Atlas has a detail part that covers the electro-magnetic coil.






These couplers are used on the SW models also.

Coupler detail for my Montour SW9 with fuel tank mounted air tanks.



Model complete.

There is another plan.

How about leaving the coupler in place and installing a small relay?  You could trigger the relay with the MTH output, and power the coupler from track power.  That would allow you to forget about tinkering with the mechanics of it, and turn it into a wiring exercise.

gunnerjohn:  As noted above, that's what I did.  One caveat:  I needed a .02 ceramic disc capacitor between relay armature & N.O. contacts to "absorb" a pulse which affected DCS.

I totally missed your response, great minds think alike.

I'd probably use a larger cap, probably a 1uf NP, but as long as it works.