[mikebiggles]

QUOTE (Tonyperks @ 11 Aug 2008, 17:52) <{POST_SNAPBACK}>As it says really, My 2 bachman cl37's judder when going down hill is this something to do with the back emf settings of the decoder, My other loco's cl47, cl20 and 66 dont do this any ideas?.

Other than this very happy set the control speed and they go up and down all day at the same speed no running away at all.
Hi Tony

Had the same problem with one of my Bachmann 108 DMU's. Turned off the back EMF and it solved the issue with no noticable difference in normal running. I have three of these units but only one of them as this problem the others run fine. So don't really know the reason why i should have to do this.

Hope this helps Mike

 

[mikebiggles]

QUOTE (Richard Johnson @ 16 Aug 2008, 14:10) <{POST_SNAPBACK}>***Because when the end bearings have too much slop, the weight of the loco going down hill forces the end of the shaft to move, changing the way the worms relate to the gears, creating a greater pressure, lesser pressure effect on the drivetrain.

This varies the motor load so it varies the back EMF it emits in a more/less/more/less cycle, creating the juddering effect.

Your turning off the back EMF masked the problem but did not actually fix it.

Adding some washers to the end bearing end of the driveshaft (inside the gera tower) at each bogie will actually fix the problem so you can turn back EMF on again.

Regards

Richard Johnson
DCCconcepts
Hi Richard
Thanks for the info, will give it a go and let you know if it cures the problem.

Cheers Mike