EMD FT-A Skids or Bottoms Out ??

[hbrown]

Hi.  Just got into this a month ago. Bought the digital commander, got addicted and then bought a mile of track, 5 locos 20 rolling stock, bla bla bla  all exclusively bachmann and all HO. . .  almost all from my lhs.  i try to keep him in business . . . loving this therapy while i wait for warmer weather to fly my rc plane/heli collection.  question:

the emd ft-a dcc that came with the digital commander doesn't appear to operate at full power, its as if it gets to 75% and that's it . . .and it exhibits unusual behavior, as if it spontaneously loses grip of the track (like its bottoming out, though its not . . . motor pitch remains constant 75%).  this will happen for a few seconds, and then its fine. . . .and it happens under all imaginable circumstances . . .dcc, dc, straight, curved, forward backward, body on/off, trucks adjusted/re-adjusted, trucks removed/reinstalled, drive shafts uninstalled/re-seated re-installed, truck bottom housing on/off . . . . . (i have 2 other new ft-a's and 1 b from you, all perfect, and i have ripped them apart to see why ther work so well . . . no conclusions)

i am new to trains, but not new to the hobby world . . . so i have no fear of noodling around with things . . . . in fact i bought your silverton/durango and out of the box the 2-8-0 failed to run smoothly . . . i diagnosed it with messed up wheel linkage, and i could have sent it back, but didn't want to wait, so i ordered the entire chassis from your parts site, installed is (like doing surgery on a grasshopper).  had to swap out the little circuit board in the wheel housing for the original, for some reason the part that came in the new chassis was not happy with the fact that i had installed the 8-pin dcc chip, or just wasn't happy . . . i then soldered in a sound decoder, found a lovely home for the speaker in the tender, and wow, this is 1 smooth running happy train . . . . .
anyway, back to the emd-ft-a . . .please advise

[jward]

it sounds like you may have a gear bind in one of the trucks. the best way to checque for this is to remove each truck and do a freewheel test. note that the worm gear must be removed from the truck for you to do this. each truck should roll freely without any binding or resistance. if one doesn't, take it apart and look for a piece of grit in the gear teeth, or anything else that would cause a bind.

[hbrown]

Ya know, I got in there to clean out gobs of grease, didn't try looking for a wormless bind. Will do.

[NarrowMinded]

You can also flip it upside down and use a marker to put a little dot on the back side of all the wheels in the same spot, then run it to see if all the dots stay insync, this will help you determine if one set of trucks is stopping while the other is stiill spinning.

NM-Jeff

[bobwrgt]

The next step also would be to check the drive shaft couplings to see if they are spinning free on the metal shaft under load. Found a lot of these split and spinning loose. The one driving the worm.
A drop of superglue usually takes care of it but be very careful where you get it.
Then check the flywheels to see if they are loose.

Bob

[hbrown]

wow, great forum.  thanks guys.  i am traveling this week.  i should have brought the train with me . . . . set it up in the hotel . . .ya know 

i will try all these things next week.

[Len]

All good suggestions of things to look at but, on a more mundane level, did you check to see if a traction tire is missing? That can also cause the symptoms you describe.

Len

[jward]

the ft does not have traction tires.

[Len]

the ft does not have traction tires.

Oh, okay. I don't own an FT myself, but have seen similar symptoms with locos that do, but lost one.

Len

[hbrown]

PROBLEM SOLVED 

It was . . . . the plastic cap that goes on the worm shaft, that connects to the driveshaft.  . .  not enough friction.  ya know, i was in there before,  and re-sat all that linkage . . . it seemed tight at the time . . . . i guess not tight enough

anyway . . . to fix it . . what i did not attempt was to glue it on.  what i did was remove it, clean it and apply a few thin coats of ultra thin ca to the inside, popped it with a little accellerator for an instant cure.  that gave it a little more meat to get a great bite on the shaft.

thanks for your help.