I have and old MRC Pennsy F7A which I recently put into service by installing a new non-sound decoder. More recently, I found a Athearn BB Pennsy F7B dummy on ebay. As anyone who is familar with the BB F-units, they were not designed for close coupling. I've been looking at ways to get a more realistic looking coupling distance between the two locos. The MRC is a little better than a BB in that regard. I got short shank KDs for both but that only improved things mariginally.
Looking at the frame of the dummy unit, it looks like I could saw off the platform that the coupler pocket clips to and then try to drill a pilot hole into the frame. The problem is the frame is fairly thin at the ends and there wouldn't be a lot left to drill into.
If anyone has done such a modification and can offer some advice, it would be appreciated. Is there a substitute frame I could use. I have one other MRC F7 which is motorized but I haven't installed a new decoder in it yet. I'm thinking of removing the motor but I don't know if that will allow the trucks to roll freely. It doesn't look like the BB dummy trucks could be swapped in but I wouldn't know for sure until I take it apart.
You need to be careful using metal KD couplers in BB frames. The frames of BB engines are part of the electrical circuit that brings power up from the rails, so the couplers will change polarity with the direction of travel of the locomotive. So, two oppositely polarized couplers that come together form a dead short.
I always mill down any metal coupler pockets and replace them with Kadee plastic boxes. The boxes have plastic sleeves around the coupler shafts, so there is no longer an issue.
It takes an iron man to play with a toy iron horse.
John-NYBWLooking at the frame of the dummy unit, it looks like I could saw off the platform that the coupler pocket clips to and then try to drill a pilot hole into the frame. The problem is the frame is fairly thin at the ends and there wouldn't be a lot left to drill into.
That will work, but do not cut off the entire pad, just file it smooth.
-Photograph by Kevin Parson
The second half of the solution is to use a 30 series coupler with a shorter shank. These will give you closer coupling, and they have more side swing than the 20 series couplers that I show.
You do not need much metal left for a secure coupler pad in an Athearn frame. I have taken the coupler mount on the frame down to 0.040" with no problems at all.
You might need to install an offset coupler to get the height correct. Resist the urge to simply bend the frame.
The pictures shows a 20 series coupler, but the mount and frame modifications are the same.
MisterBeasleyYou need to be careful using metal KD couplers in BB frames.
Absolutely! The 20 series and 30 series Kadee couplers are non-conductive, and are the only couplers I use on Athearn BB locomotives.
I hope this helped.
-Kevin
Living the dream.
LION removes the couplers completely! Use drawbars instead, plastic drawbars!
If both A units are powered, as they should be, you should pass a pair of wires from one loco to the next so that all of the units will pick u; power in unison. MU units.
My "B" units were once power units, and so these trucks too collect power. The heavier frames make for beter tracking that the lighter Atheran B units.
If you are using track gaps to stop trains in hidden yards or staging areas you will need to have the units all powered together, for neither unit can shove a dead unit.
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
All excellent suggestions. I already have the short shank couplers installed. I'm intrigued by the drawbar suggestion. I don't know why I didn't think of that. I have two P1K F3 A/B sets that I replaced the couplers with drawbars. That was about 15 years ago and they have given me no trouble since. Someone suggested I use a cut up credit card for material and that has held up all these years. Just cut it to the appropriate length, drill a couple holes, paint it black and put it into place. I just have to figure out how long to make the bar. I like this suggestion because I think I can use the existing coupler pockets without filing them down. If it doesn't work out, I can always try the other suggestions. I'll probably do that for the opposite end anyway.
Good luck, John. The drawbar is a good suggestion. Just be careful to take into consideration the diaphragms. When you get the locos that close together, derailments on curves can become a problem.
Rich
Alton Junction
John-NYBWSomeone suggested I use a cut up credit card for material and that has held up all these years. Just cut it to the appropriate length, drill a couple holes, paint it black and put it into place.
What a good idea. The suggestion I read was to use the plastic from a motor oil bottle, which is bendy and may already be black, but will have to be cleaned up.
Gary
John-NYBW I have and old MRC Pennsy F7A which I recently put into service by installing a new non-sound decoder. More recently, I found a Athearn BB Pennsy F7B dummy on ebay. As anyone who is familar with the BB F-units, they were not designed for close coupling. I've been looking at ways to get a more realistic looking coupling distance between the two locos. The MRC is a little better than a BB in that regard. I got short shank KDs for both but that only improved things mariginally. Looking at the frame of the dummy unit, it looks like I could saw off the platform that the coupler pocket clips to and then try to drill a pilot hole into the frame. The problem is the frame is fairly thin at the ends and there wouldn't be a lot left to drill into. If anyone has done such a modification and can offer some advice, it would be appreciated. Is there a substitute frame I could use. I have one other MRC F7 which is motorized but I haven't installed a new decoder in it yet. I'm thinking of removing the motor but I don't know if that will allow the trucks to roll freely. It doesn't look like the BB dummy trucks could be swapped in but I wouldn't know for sure until I take it apart.
The best way to close couple old Athearn F units is with this simple kit.
https://www.americanlimitedmodels.com/ho-athearn-f-unit-close-coupling-adapter-kit-black/
Or, with diaphragms:
https://www.americanlimitedmodels.com/ho-athearn-f-unit-connection-kit-black/
Sheldon
Right now they don't have diaphragms. My go-to diaphragm is the Walthers rubber ones. Fairly thin but give the proper look. I normally try to leave a very small gap between the diaphragms when installing coupler boxes on cars that had truck mounted couplers. I'll do the same with the drawbar. I just wanted to eliminate the unrealistic gap between the A and B units as well as from the back of the B unit to the first car in a passenger consist.
John-NYBW Right now they don't have diaphragms. My go-to diaphragm is the Walthers rubber ones. Fairly thin but give the proper look. I normally try to leave a very small gap between the diaphragms when installing coupler boxes on cars that had truck mounted couplers. I'll do the same with the drawbar. I just wanted to eliminate the unrealistic gap between the A and B units as well as from the back of the B unit to the first car in a passenger consist.
Well ok, whatever.
garya John-NYBW Someone suggested I use a cut up credit card for material and that has held up all these years. Just cut it to the appropriate length, drill a couple holes, paint it black and put it into place. What a good idea. The suggestion I read was to use the plastic from a motor oil bottle, which is bendy and may already be black, but will have to be cleaned up.
John-NYBW Someone suggested I use a cut up credit card for material and that has held up all these years. Just cut it to the appropriate length, drill a couple holes, paint it black and put it into place.
As it turns out, the newer credit cards with the chip technology seem to have a thin metal layer sandwiched between the plastic. I used a recently expired card and broke a drill bit before I figured it out. Fortunately, I found a scrap piece of styrene in my junk drawer that was exactly the right width and thickness for this application. I ended up drilling the holes in the drawbar 5/8" apart and this turned out to be the perfect distance to get close coupling after adding the Walthers rubber diaphragms. This of course could vary depending on the locos and diaphragms used.
Another good thing to make drawbars out of is an old advertising keychain. The rubbery plastic will give without breaking and they are about the right thickness.