Rack loco judder

[scook]

Hi all,

I have two lgb rack locos that judder downhill on a 12% gradient rack section.

One is a schb box cab loco fitted with a lgb 55021 decoder , the other is a lgb dfb steam rack loco fitted with I believe a mfx decoder , they perform like this on both analogue and digital.

Any ideas?

Thanks
Sam

 

[craigwrdouglas2]

Interesting - I have both of those as well on my rack system

It could be a few things -
1. does it do this with loco only?
2. Is it a tension lock issue? that is is the loco taking a hit from the train vehicles going over a tipping point - remember it's doing braking for the train on the downslope and the tension-lock couplers will switch from pulling to holding the train back on the downslope.
3. if it's taking a hit from the train that will impact, load compensation which may take a moment to settle.
4. you could try knuckles instead of tension locks, so the train length doesn't change switching to downhill, or switching stock to plastic wheels to cut down on the weight of the train.
5. you may also want to look at cv 51 - load compensation and setting it to compensate less aggressively might make your judder less harsh.

hope this helps.

 

[scook]

Interesting - I have both of those as well on my rack system

It could be a few things -
1. does it do this with loco only?
2. Is it a tension lock issue? that is is the loco taking a hit from the train vehicles going over a tipping point - remember it's doing braking for the train on the downslope and the tension-lock couplers will switch from pulling to holding the train back on the downslope.
3. if it's taking a hit from the train that will impact, load compensation which may take a moment to settle.
4. you could try knuckles instead of tension locks, so the train length doesn't change switching to downhill, or switching stock to plastic wheels to cut down on the weight of the train.
5. you may also want to look at cv 51 - load compensation and setting it to compensate less aggressively might make your judder less harsh.

hope this helps.

View attachment 355585

Thanks for the info,

Both locos judder without any stock,

Regarding cv51 is there a table for cv values?

Thanks
Sam