Chuffing problem with Big Boy

On one of my Legacy steamers had the same problem, and it took me for quite a ride!

The syptoms were as yours. I would remove the shell, inspect, re-assemble, and it was all good for awhile. Often I was getting 3 uneven chuffs per revolution, and finally the cruise became lurchy and jerky. 

     What I finally found, was when they pressed the plastic timer on the flywheel a very thin ring shaved off and fell in a helical position behind the windows of the timer. When the loco was turned over to disassemble the ring would fall back out of site! It would then run well for a day or two then the same thing over again. It took several days and much frustration before I found the problem. It is very hard to see.

    Just something you might check.

 

Bill

I will have to look at that.  Unfortunately I am not familiar with the parts you are talking about.  When I had the shell off the other day I did notice there is a black ring with slots in it on one of the motor flywheels, almost looks like a squirrel cage fan.  Is this the timer you are referring to?  Where are the windows you are talking about?  Underneath?  Another weird thing I have noticed is that if I turn off railsounds, the smoke unit seems to work normally, but with railsounds on, it flutters on and off with the chuffing.

Your unit uses a cherry switch that makes contact with a cam to send the chuff signal and also trigger the fan motor to operate to make smoke puff.  The switch can be out of adjustment.

 

The fact it may smoke better when sounds off throws a wrinkle.  You could try reseating the RS boards in the tender, then do the same with the R4LC in the engine when you check how the limit switch is working.   G

The windows I was talking about are the slots in the black ring. The offending ring was evidently shaved off when the ring with the slots was pressed on the flywheel. The offending ring was as thin as a hair. Rotating the flywheel, it could be seen behind the slots. When I removed the flywheel the hair like ring fell against the flywheel and was practically invisible. I thought maybe I was seeing things but turning the flywheel over the ring fell behind the slots again. I fished it out with a small hook shaped wire. The engine is an MKT 0-8-0 Legacy. I believe it has a Cherry switch, but never the less the chuff sound was only 3 chuffs per wheel revolution, and at times the cruise control was hercy-jerky. I can't remember about the smoke, I think it was turned off.   

So I took off the shell last night and inspected the flywheel and couldn't see anything out of the ordinary.  I ran the engine around without the shell and it still skipped chuffs a little, but after a while, it was running fairly well and only skipping chuffs every so often, to the point I would be willing to put up with it.  I put the shell back on and it went straight back to skipping chuffs quite regularly.  Also, I did notice a very faint "blurp" coming from the speaker every so often, kind of an electrical beep.  Don't know if that is related at all.

Did you reseat the board in the engine?  Could be the shell is pressing wire bundle and board.  Check cherry switch for operation, could be minor mis-adjustment?

I had a Lionmaster Cabforward that was doing the same kind of thing.

I am with GGG; likely the cherry switch operating arm slightly out of adjustment. A little tweaking fixed the Cabforward up and it has not missed a beat since.

 

Rod

I think about half the chuff issues I've had with locomotives has been the chuff switch.  Usually, I just do a little creative bending of the actuating arm to beat it into submission.

 

I haven't reseated the board.  I will try that, but I still am not sure what/where the cherry switch is?  There is a little tab that sticks up from the board that sits next to the flywheel, is that the cherry switch?  If so, the cherry switch doesn't actually have moving parts correct? 

The switch in question is buried at the bottom of the locomotive.  There is a cam on one of the axles that activates it.  It does indeed have a moving part.

 

I know this is simple but I have a m1b that did the same thing, turned out the IR detector between the tender and locomotive was misaligned, even the cover clip that aligned the draw bar did not prevent it. Check to see this is not the case.

Good suggestion, I will check into that as well. Thanks.

 

If the IR is misaligned the smoke puffing will still be in sync.  I believe he said the smoke puff and sound both cut out.

 

Jim

The fact that the smoke also doesn't puff with the chuff is a clear indication this is not the IR link.  The IR link is a one-way link, it can't affect the smoke unit.

 

I took off the front drivers tonight and spotted the cherry switch. It is on the very front wheel. I took it out and pressed on the switch a few times and it seemed to work normally. I reinstalled it and put everything back together and who knows what I did but it's working now.  Hooray!!!! Thanks everybody for the help. Hopefully it stays working and it's not just a fluke that it's working.

Good job.  Could have had some debris that needed manual clearing from cycling the lever fully.  G

If it fails again, try bending the lever a bit to give it more "bite", that's usually what I end up doing.