Quartering Lehamnn 92179 chassis

R

Rackman

Registered
Hi,
following a controller failure (successfully fixed), I am fettling my locos for what we laughingly call spring.
I removed a hefty lump of twig that had firmly jammed the wheels of my GRS Prince last autumn ! which was built on a Lehman 92179 chassis.

Extracting the twig was quite a wrestling match but test running the loco gives a stop-go-stop-go lurching movement, so I am assuming that the quartering is off, although it looks OK on a visual inspection.


I couldn't find a service manual on line, so I was a bit wary about opening it up.
Any help and suggestions greatfully received.
Paul
 
Champex Linden's database is my usual "go to" for LGB service sheets.

https://www.champex-linden.de/lgb_p...443927b513dc125691c0045fb8718dd.html?OpenView

92179 isn't specifically listed, but there are plenty of others with essentially the same mechanism.

https://www.champex-linden.de/lgb_p...1CDB4E386B285256EE10008400F/$FILE/92178-1.pdf

Sometimes the gearing has only jumped by one tooth, which is enough to cause running problems but can be more difficult to spot visually. I would apply low power and try to arrange the loco so that the wheels on one side are both TDC or BDC (Top Dead Centre or Bottom Dead Centre) in terms of the cranks. If the gearing has jumped, you should be able to see that one axle is slightly out.
 
Agree with the above..
It can be quite difficult to see which way to go, as there is some 'slop' in the mechanism.

If in doubt, move 'one tooth' one way, drop the bottom back on and try it.. Remember to note which way you moved it!.

Sometimes one wheel can have rotated slightly on the axle, this means things can get tight at one point in the revolution.
If you set one side 'TDC' you can then compare the crank positions on the other side. Repeat with the second side 'TDC'..
 
If you're not certain it's a quartering problem just remove the coupling rods.
If it runs OK without them it's likely a quartering problem, but could be a bent or sticky cross-head.
If it still lurches it could be the backs of the wheels need cleaning or the springs for the carbon brushes are weak or stuck. Worse still it could be that a tooth in the gearbox was damaged when the twig got jammed. I hope its' just the quartering!
 
Hi guys,
thanks for the advice, I opened it up and it had indeed jumped one cog - runs just fine now - thank.
Paul
 
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