I recently acquired a 681 Turbine and have a probelem

Did you check the E-unit? Did you make sure the drum is in good shape? E-unit contacts clean? The E-unit handles F-N-R and they can get dirty. Another problem is bent contacts or the drum breaking or loosing teeth. I have a 671 that needs a new drum and contacts, and it had problems with the f-n-r sequence. 

The E-unit functions fine, FNR.  I cleaned the drum and contacts were clean and making good contact with the drum.  I did not have to do anything else with them.  

The axle bushings on the powered axle are worn, shifting the worm wheel off center from the worm and the driver into the chassis in forward.

The alignment is all good when it's in reverse, so it runs better.

The right rear axle bushing is always the one that wears out first(from forward operation), pushing the axle left, the right rear wheel into the frame, and the worm wheel off center.

Of course, the factory fix is to replace the bushing, which requires pulling the 4 rear wheels(two flanged & 2 blind), pressing out the axle from the worm wheel(gear) and the frame, pressing out and replacing the worn bushing(s), and then pressing the axle back in to the chassis and worm wheel, and quartering & pressing the 4 wheels back on.

For an easy fix that will last a long time, use one(or two or as needed) 671M-22 clips/retaining rings and snap them on to the drive axle to the left of the worm wheel.  You want to have between half to the full width of a 671M-22 clip of end play in the axle for best performance. Keep the entire gearbox & axle lubed well with a synthetic HP grease(Lucas Red 'N' Tacky #2, eg.).

If you can source some clips with the same inner diameter as the 671M-22, but larger outer diameter, that would be beneficial.  The last good tip I heard was to use an appropriate number of plastic bread closure clips(cut to be round) instead of the 671M-22.  Very little friction with that method and they too slip right over the axle and stay on.

It is also very important on these to make sure the side rods are not excessively worn and they are oiled with a good synthetic.  They transmit power from the geared axle to the other three.

I should also add that with the shell off, the motor turns slower at first in forward, making noise, then after a couple of seconds running, the motor speeds up and the noise goes away.  With the shell on, the motor turns slowly like I stated above, with noise, but it does not speed up after a few seconds and the noise does not go away.  Really bizarre if I say so myself.  

Pennsyfan713 posted:

Did you check the E-unit? .....

Another problem is bent contacts or the drum breaking or loosing teeth. 

Are you saying his E unit may have "loose" teeth, or they may be "losing/lost" teeth??

ADCX Rob posted:

The axle bushings on the powered axle are worn, shifting the worm wheel off center from the worm and the driver into the chassis in forward.

The alignment is all good when it's in reverse, so it runs better.

The right rear axle bushing is always the one that wears out first(from forward operation), pushing the axle left, the right rear wheel into the frame, and the worm wheel off center.

Of course, the factory fix is to replace the bushing, which requires pulling the 4 rear wheels(two flanged & 2 blind), pressing out the axle from the worm wheel(gear) and the frame, pressing out and replacing the worn bushing(s), and then pressing the axle back in to the chassis and worm wheel, and quartering & pressing the 4 wheels back on.

For an easy fix that will last a long time, use one(or two or as needed) 671M-22 clips/retaining rings and snap them on to the drive axle to the left of the worm wheel.  You want to have between half to the full width of a 671M-22 clip of end play in the axle for best performance. Keep the entire gearbox & axle lubed well with a synthetic HP grease(Lucas Red 'N' Tacky #2, eg.).

If you can source some clips with the same inner diameter as the 671M-22, but larger outer diameter, that would be beneficial.  The last good tip I heard was to use an appropriate number of plastic bread closure clips(cut to be round) instead of the 671M-22.  Very little friction with that method and they too slip right over the axle and stay on.

It is also very important on these to make sure the side rods are not excessively worn and they are oiled with a good synthetic.  They transmit power from the geared axle to the other three.

ADCX Rob, thank you.  Seems like you are speaking from experience.  I will try your suggestion.  Unless of course, I find a lower mileage chassis at the next train show.

George, Rob is correct, he hit the nail on the head. Basically what’s happening is the driver is rubbing the frame acting like a very effective brake shoe and slowing your locomotive down. The increased load of the motor working harder to overcome this friction is why you are seeing more “sparks” out of the armature....on my own equipment I have used the bread bag clip trick and it indeed does work..........Pat

Does anyone have a picture of the repair as described by ADCX Rob or Harmonyards?  I'm just not seeing how this is executed.

george posted:

Does anyone have a picture of the repair as described by ADCX Rob or Harmonyards?  I'm just not seeing how this is executed.

Simple, pop the cover off the gear well. Make the “ spacers” as described by Rob from bread bag clips. Add as many of the spacers as needed to keep the driver off the frame and the worm wheel centered. Manufacture your spacers so they are not bigger than the worm wheel itself. Bread bag clips are tough nylon plastic so they will last a long time.....it’s an easy fix .....way easier than the alternative of pulling drivers and pressing gears and bushings......you can even make extra spacers from one bread bag clip if you are handy with a drill and a pair of nippers...drill a hole in the bread bag clip just slightly bigger than the axle. Then trim around the hole to make a washer, then cut a slit big enough to snap over the axle, and it will stay put............Pat

Train Nut posted:

Pennsyfan713 posted:

Did you check the E-unit? .....

Another problem is bent contacts or the drum breaking or loosing teeth. 

Are you saying his E unit may have "loose" teeth, or they may be "losing/lost" teeth??

Lost teeth, I’ve seen those drums break quite a few times. Glad to hear it isn’t the E-unit. Taking those apart and reassembling them is a pain in the rear.

george posted:

Does anyone have a picture of the repair as described by ADCX Rob or Harmonyards?  I'm just not seeing how this is executed.

Put the spacers clipped to the axle here:

E-units are much much much easier to repair than axel bushings 

YES they are Matt!