LGB Mogul 23194 DCC loco small surges or 'jerks' as it goes down inclines

[beavercreek]

Not sure whether to put this into this or the DCC section of the forum.

I have a LGB mogul 23194 which is factory DCC and sound and made in Germany.

I noticed while it was ploughing its way around my 'Local' line, that when going down hill (any amount of gradient), it slightly surges or jerks as if it had 'play' in the drive train and it was catching up with itself.
I was using on 14 speed steps.
When it was going up hill, everything was fine.
I tested it by just pushing and rocking it back and forth, without any power, and although this model of loco is very easy to push the motion (no real reduction gearing), it did not have much loose play at all.

Now it probably has an older LGB decoder and maybe the back-emf is not so flexible to account for downhill running.
As it is a very free running mechanism, perhaps the back-emf cannot compensate fully for the fact that the loco will want to 'runaway' if it has a load behind it (even just the tender on its own) whilst going downhill......but this was happening even on the lowest downhill gradient not just on my 'horrendous' ones!

Has anyone experienced this and is there a CV cure? ???

 

[Phil]

Try looking at the quartering, this might be out, sometimes causes locos to run jerkily..
Just a suggestion..

 

[kim]

This must be catching Mike, one of my older Moguls, all factory fitted, was out a few days ago and is slowing on bends with just 3 coaches, back emf is suspected.
Kim

 

[stevelewis]

I seenm to recall that back in my 'USA G scale period' my Moguls had a tendency to run 'lumpily' down gardients, but when I double headed them the problem disappeared, I really have no idea why this occured and it was pre digital era as well.

I recall that there may have been some comment about this at that time in the Mags, some comment that this loco type along with the RhB 2/4 Boxcab electric ( 2-4-2 wheel arrangement) were the first of the larger wheeled locos that LGB introduced ( 41mm dia drivers ?) and this may have been a reason as the gears were not quite correct, although I also had one of the Box cabs later and never noticed any down hill running problems

 

[beavercreek]

Hi Phil
The quartering is spot on but I do suspect the back-emf and maybe its relationship with the gearing (as Steve alludes to in his post about the mogul back in time).
The gearing is really free running, in fact the only other loco that I know that runs freer is the Bachmann K27. That can practically be pushed along with your pinky!

Kim....my moguls are really gutless when they see my incline when they are pulling four cars or so....they just spin their wheels

 

[Beddhist]

Why don't you try it on DC downhill? If it still jerks then it is mechanical (like my rail truck). If it doesn't jerk on DC then the problem is electronic.

 

[PhilP]

I think you will find it is the general 'slop' in the motion..
I have a number of these on the bench at present (must get a bigger bench! ) and they all 'hesitate' at slow speed.. I would expect running downhill, the load would tend to push against the motor/motion, and the same effect would cause the 'jerk'??

One of these (Chinese block) has an annoying 'click', which moves round the motion-point it sounds. - Clicks at a different point each rotation of the drivers. It must be in the intermediate gearing, but I am blowed if I can find it..
Motor has been swapped, so next must be the intermediate gears..

 

[PhilP]

Off topic, but could a 720 engine ever have run with a C & S liveried tender??

 

[beavercreek]

[quote author=PhilP link=topic=301468.msg354601#msg354601 date=1435151485]
Off topic, but could a 720 engine ever have run with a C & S liveried tender??
[/quote]
Phil are you alluding to a D&RGW T28 (4-6-0) running number 720 standard gauge loco?
If you are then probably not..... but C&S did run standard gauge from Denver to Pueblo so there could be a possibility so there is a reason to run it...............