U class binding issue

[Anglian]

Afternoon all.
I'm having a problem with a 1995 U Class that I'm very fond of. It has started to run very jerkily. I've taken the base off and was running it upside down. The jerking is more pronounced when running forward and there seems to be a lot of slop in the back axle. Your experience would be greatly appreciated.
Secondly, part of the plastic motion rods has fractured and I was wondering whether spares are still available and if so, from where? Those who know me on this forum are aware that my knowledge of dismantling and fabricating is progressing but still limited when it comes to engines.
Trevor

 

[Rhinochugger]

Wasn't this the 'Achilles heel' of this loco?

One of my foibles was to refer to this problem every time somebody claimed that LGB were perfect / bullet proof

 

[dunnyrail]

Afternoon all.
I'm having a problem with a 1995 U Class that I'm very fond of. It has started to run very jerkily. I've taken the base off and was running it upside down. The jerking is more pronounced when running forward and there seems to be a lot of slop in the back axle. Your experience would be greatly appreciated.
Secondly, part of the plastic motion rods has fractured and I was wondering whether spares are still available and if so, from where? Those who know me on this forum are aware that my knowledge of dismantling and fabricating is progressing but still limited when it comes to engines.
Trevor

Quite often the gear gets one or two cogs out of synk, this can cause lumpy running. Have a careful look at the front, middle and rear spokes, just one. Are all 3 pointing exactly the same? If not taking off the bottom plate and adjustment should resolve the issue. While you are in there look to see if tye main gear on the axle has split this could also be your problem. As for the motion rods, if you cant get a spare repairing with small BA s rews and a flat piece of fabricated thin brass or nickel silver sheet will do a good job.

 

[Greg Elmassian]

The key in Jon's post is "exactly" just to agree strongly.

Broken siderods are often what happens if you slip a tooth or the driver slips in relation to the gear.

Greg

 

[Anglian]

Whoops, forgot the pictures.

 

[Anglian]

Thanks for the responses. I know now what to look for.
T

 

[Greg Elmassian]

Need side view (both sides) so you can visually "line" up the drivers, usually you use the counterweights to do this visually.

Greg

 

[PhilP]

This may not be for this model, so be prepared to ignore this:

Was it the U-class, that had the dangly/reverser bits, within the motion? These could occasionally 'flip', so would be sticking up (if they should be down), or down (if they should be up)..

They then tended to jam/Bind, and things bent/broke..

PhilP

 

[Anglian]

I had a look at both sides. One seemed a little out, so I made an adjustment. It looks correct now and seems to be running more smoothly. I can check this outside tomorrow the right way up. I shall have to fasten down what Phil might describe as, 'a dangly bit', which is attached to the broken part, so it doesn't catch up with the rest of the motion.
Thanks folks.

 

[Greg Elmassian]

Good time to check if any driver is loose (rotationally), use some firm pressure to make sure each driver (all 6 individually) is not loose and cannot slip.

Greg

 

[Anglian]

Thanks Greg and all.
Trevor

 

[stevedenver]

Another potential slop cause is the u shaped area where the axels sit In the motor block.
With lots of run time, heavy loads, the u slots can become worn and enlarged, eliptical. Only a slight change will cause gear teeth to slip.
If this is the issue, you will need to replace the motor box. Even with new gears, and correct quartering, the gears will continue to slip unless the axels sit in proper slots.