R.305 Duchess running badly post-service

[Alessio]

I've got an early 80s R.305 Duchess of Abercorn which was given to me as a gift. Recently I got it out to run for the first time in probably 18 months, and it went about 4 inches and stopped. I gave it a nudge and the same again happened.

Given how long since it had last run, I decided to service it. I stripped down the motor following the instructions of a YT video, cleaned everything with dry cotton buds, cleaned the brass coil thing with a few drops of lighter fluid, fitted new springs (carbon brushes looked ok and I only had one spare left) and then rebuild, oiling everywhere that I was instructed by the video.

Now, the engine runs slightly better, but every 8 inches or so, it stutters slightly and then carries on the same again. At least it can make it round a full circuit now and at full speed seems to run almost normally but at anything up to 75% it stutters at regular intervals.

It's almost as if there's some point of the motor's cycle where it isn't making proper contact but having rebuilt it I can't work out what's up. Can anyone help?

 

Thanks!

 

[Lancing]

Alessio - that sounds lke an electrical fault, possibly something just making contact until it vibrates out of contact. Look at the electrical pick-ups first - are they making good contact with the wheels, if yes, then remove the body and check all the wiring very carefully to see if anything is loose. If it all looks sound it may be what's known as a 'dry joint', ie a poorly soldered joint. These are tricky to spot, but if any soldered joint looks dull grey rather than silver, that might be the problem.   

[jane1707819582]

To eliminate one from the tother can you rig up a controller straight on to the motor connections in the tender .Start at a slow speed ,slowly raising the volts on the motor .Undercutting the comm  on the motor also helps .also check that the side to side movement on the comm is not excessive.

[Going Spare]

The early Duchess locos do not have pick-ups, the electical path from the loco being via the non-insulated driving wheels and axles to the chassis block thence via the drawbar to the tender pin, the motor, and back to the track via the non-tyred wheels on the tender.  If you have serviced the tender, which presumably included cleaning the wheel treads, I would check the cleanliness of the loco wheels, the contact points where the pony truck is screwed to the loco chassis block and the contact jaws on the drawbar.  If you contemplate removing the loco chassis bottom casting, do so only with the greatest care because that casting is notorious for suffering from mazak rot and would be extremely difficult to replace.

[Puffed Out]

Is the track clean enough. Are the joins/fishplates tight enough. Over oiling is never a good thing.

[Alessio]

Thanks, I'll take all these and have a look, see if I can work out what it is. All I can say is that other engines (aside from one) run fine around that loop so it must be the loco!

[ColinB]

The thing you should check is if someone has over oiled the axles on the loco. This loco picks up one side of the 12 volt supply via the axles and axles on the tender pick up the other side, meaning it doesn't need pickups. I have done it to mine in the past. If you over oil the loco wheels, excessive oil gets on the axles of the loco wheels which acts as a great insulator. The other fault you may have is that one of the windings on the motor is not connected. Try the loco axles first. If it is the same as mine, it is tender driven, so check that the valve gear on the loco moves freely, round bends if the valve gear has an issue it can slow the loco down. Lastly the loco wheels may have a film of oxide on them in certain places acting as an insulator.

[Alessio]

Thanks all... ridiculously it would seem that despite having owned this model for over 15 years I'd failed to check the connection between loco and tender. It now runs like a dream. I've just had it run with 11 coaches on and it was fine. Win!