LGB 21741 - Developed Jerk / Slog

[curtis]

A few months ago, one of my favourite locos, an LGB 21741 began to run awkwardly. It developed a jerk/slog forward seemingly of its own volition. The thing that I found odd was it happened not after being disassembled/opened but after a long running session. Due to life / the universe getting in the way I've only just got around to starting to look into it. I've included a video below of the issue.

My initial though is that something is out of alignment or there is an issue with the motor. I opened it up and lifted the axels so the gears were not making contact with motor. I'm not noticing the same pulsed nature but again the motor isn't under any kind of load so I'm not sure if I would see anything.

I'm newer to the more mechanical side of maintaining the fleet so before I do too much digging I wanted to seek the communal wisdom of the group to ensure I'm not overlooking something stupid.

 

[dunnyrail]

A few months ago, one of my favourite locos, an LGB 21741 began to run awkwardly. It developed a jerk/slog forward seemingly of its own volition. The thing that I found odd was it happened not after being disassembled/opened but after a long running session. Due to life / the universe getting in the way I've only just got around to starting to look into it. I've included a video below of the issue.

My initial though is that something is out of alignment or there is an issue with the motor. I opened it up and lifted the axels so the gears were not making contact with motor. I'm not noticing the same pulsed nature but again the motor isn't under any kind of load so I'm not sure if I would see anything.

I'm newer to the more mechanical side of maintaining the fleet so before I do too much digging I wanted to seek the communal wisdom of the group to ensure I'm not overlooking something stupid.

That looks to be a classic case of gear cog misalignment.

What can happen is that one of the gear slips putting one of the sets of driving wheels out of alignment. Recently had one of them to bits to fix and that had the same issue.

What to do to diagnose it is get the axle on the front driver so that it is exactly vertical at the bottom. Use the axle as close to centre of the weight, weight being to the top. Now observe the axle on the rear and you should find a small misalignment, it is often just a cog or two.

Fix. Turn upside down supported on some foam, undo the screws on the base and move the axle just enough so that the spokes are in perfect alignment then screw up and retest. Make sure that the base plate has nestled down with no gaps between it and the frame as visible from a side view.

The cause of this can be through extended running with a heavy load, the cogs just slip. Some LGB locomotives appears more prone to this issue than others, Trainline 45 locomotives can have the issue also.

 

[curtis]

Thanks so much, Dunny.

This is my hypothesis but before I blindly went poking too much I wanted to check and use it as a learning opportunity. Got 15mins this morning and was able to get it running again very elegantly. Really appreciate the run-book on how to fix it.

The cause of this can be through extended running with a heavy load, the cogs just slip. Some LGB locomotives appears more prone to this issue than others, Trainline 45 locomotives can have the issue also.

Also, thanks for explaining the root cause. Sounds right - it spent 3 days running on R2/R1 curves at the exhibition I'm sure there was enough load/drag there for to create that situation.