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LGB 2085D European Mallet runs rough moving forward but runs fine backwards

My LGB 2085D European Mallet runs rough moving forward but seems to run fine backwards. I’ve cleaned the wheels thoroughly as I know these locos have issues with the wheel pickups. Could this be that one or both of the motors is bad or the wheel pickup brushes?

Thanks for any ideas and suggestions.

Pick it up and turn it around OR
Move to the other hemisphere.
The best solutions are often the simplest.


When you throw into forward, can you hear any noises, or does it go silent? Is it possible that the motor is spinning but for some reasons, the rods bind when it goes forward?


I would disconnect the power source to each truck assembly and test each one separately. You can use the transformer and a set of wires to check this and run both in each direction, this should tell which wheel assembly, motor, etc. it is. If it’s a gear spinning on the axle these are available from a LGB supplier and can easily be replaced. I some cases the gear and axle can be re-glued, but this will take a little knowledge on how to do it. Don’t think it would be the pickups as if in runs in one direction ok, then it’s getting power to the motor. First find out which motor assembly it is that won’t run in both directions smoothly.

Pit it up on a set of rollers and see if it needs to be quartered. run it real slow and watch the linkage. LGB-s have been known to go out of quarter. My mallet has done it twice.

I does move forward however it stutters and stops.

I’m not clear what you mean by “out of quartered”.

Every once in s while it the main gear on the motor may jump a tooth or two from the axle gear. It is because LGB’s are very flexiible. This puts one side of the valve gear and rods out of synch with the other side. It will bind either going forward or backwards or both if it is severe enough. That is called going out of quarter.
A set of test rollers is the best way to check any problems on a work bench. Every modeler should have a set of four.

Technically, on a steam-driven railway locomotive, we ‘quarter’ the wheels on opposite sides - which means we set one side 90 degrees (a quarter) different from the other side. If you think about the steam in the cylinders pushing or pulling on the piston and rod to the wheels, then one side will always be in the middle of the power stroke when the other side is at the end and changing piston direction. Hence the need to ‘quarter’ the wheels on opposite sides.

When you have more than 2 wheels (almost always!) then the wheels are kept in sync by the main rods, which act in unison so all the wheels follow the ones being pushed/pulled by the steam.

However, if one wheel slips a bit on its axle so it isn’t perfectly in unison, the rod will bind and stick when rotating. It’s often easy to spot as the wheels go around almost 180 degrees then appear to have a problem and slow, then they get over it and continue; a slow-go-slow-go every revolution.

That isn’t the same a running ‘rough’, or maybe it is?

John, I am very curious how the gear jumping can put the valve gear and rods out of sync? Surely both are connected to the same axle that is driven by the gears?

However, if the motor drives 2 of the axles and the wheels are connected by rods, then if one end jumps a tooth, that end will be out of sync and will bind the rods and fight against the other axle that is driven.

There is enough “slop” in LGB rods that one side may not be effected if the gear jumped one tooth.
The old moguls would go out of quarter now and then as well.

I have a set of 4. How do i check then if it is binding?

Also, does anyone have an exploded view of this locomotive?
2085D-1.pdf (1.2 MB)

Thanks for the info David

I’ve never had slippage of any LGB Locomotive, but not saying it’s not possible, were talking gears, axles, side rods, etc. I would remove the total drive block, mark the wheels with a marker, try to mark one side against the other, keep in mind the wheels should be quartered, one side against the other. Run the block from a power supply and see what is going on. You could also hold one set of wheels on the same axle and see if there is play between the two sides. These are just some of the things I would try to isolate the problem. I would think it’s just one motor block that is the problem, so one is working against the other and one is working just fine. Make sure all the side rods are working correctly and not binding, plus look at the rod that goes into the steam Cylinder and make sure there is no binding there also. Actually running the block should show up pretty quick what the problem is, this is with a good knowledge on mechanical repairs and if mechanical and electric repairs are new to you, this is your chance to learn, we all started at one time.


I have a venerable LGB locomotive that has caused me fits over the years ( LGB 0-6-2T: BadMotor, Bad Gears, Both, or Something Else?). Scan that long-running entry, and you will find that:

a.) I learned a lot.
b.) I spent a lot.

I had a large scale (but not LGB specific) shop and an hobbyist “expert” try to fix Gustav along the way. Ultimately, I should have packed it off to TrainLi when my initial attempt at home repair fell short. It turned out the the old boy needed an entirely new chassis and new wheel sets after 10+ years of service and a quarter century in storage. It would have saved me money in the long run (probably the cost of just replacing “him” with a less well-worn used model), and none of those lessons would have been lost as I slowly progressed deeper into this hobby.


I have a set of 4 rollers. I am not clear what I am checking for. When I place this loco on the rollers it opperates just fine forward and backwards.

I downloaded the exploded view of this loco however, I can’t determine how to remove the motor blocks.

Can anyone help me figure out how to remove the motor blocks on this locomotive?


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