Rack loco Jerky at Low Speeds

lynxface

lynxface

Registered
Country flag
Hi everyone!

Here's a funny one: my new LGB ballenberg rack loco has had a new Massoth XLS chip installed and is running very nicely. Except for one thing: at low speed (only speed steps one or two on MTS II) it is jolty.

The problem never existed with the old MFX decoder (before it blew - sigh), and the engine is only 2 years old, so I'm leaning towards thinking it might be decoder settings. Looking around here, I'm seeing that back EMF could be the culprit but I'm wondering if anyone else has any other ideas. The quartering is all fine too.

Thanks in advance for any genius diagnostic suggestions!

Alex
 
You say it is new?
Sounds like something is a little tight? - It may well improve with use??

I would check that nothing is catching the motion. - Could be one of the pivot screws is slightly loose and catching?

It could be better in one direction? - Do you have rollers (or a couple of blocks) you can run the loco on? - Run it at a medium-speed for 40 minutes in both forwards and reverse. See if it improves.


Double-check the quartering.. It might only need one axle moving one-tooth, one way or the other..
 
If it is anything like my old one there was a distinct lack of pickups, in the end I retro added wire wipers to all 6 wheels that transformed the running.
 
It does sound like back EMF setting to me, like the reaction time is too slow. Like Greg Elmassian Greg Elmassian said in post #2 check all those things and then try with bemf on and off (I think that is a bit setting in CV 49). When it is off you will need more volts for it to move (higher speed step) but if it is not jerky then bemf may be the cause, then you can report back.
 
Yup, back EMF it was, folks. Running lovely now. Thanks very much for advice. Was my first real entre in programming CVs with the LGB 55015 (other than accel/decel/addresses) so pleased I didn't bugger it up.

Thanks
 
Out of interest what did you change? Did you turn bemf off completely or adjust it?
 
Hmm
i have the same problem with my Zugspitz going downhill only OK on the flat and uphill, I'll give it a try
 
You must log in or register to reply here.
Back
Top Bottom