Locomotive 'juddering' at low speed

[markSandD]

Hi, can anyone help with this one at all?

I am using the Hornby Sapphire Decoder in a locomotive which is fine. The problem I am having is that I cannot get the loco to run smoothly at lower speeds. The only way I can describe it is a kind of juddering

as the loco is moving in either direction.

I have tried to alter the settigs of the Decoder, 'back EMF', the 'acceleration level', I even tried it with the 'Shunting function' on and off , altering the 'back EMF' to a low level, makes the loco run smoothly

at higher speeds, but the speed fluctuates, and the loco is difficult to get moving with a train behind it at higher speeds, and makes it very difficult to get moving at lower speeds.

Anyone had experience of this issue before?

[Gregd99]

when I saw the title I thought.... back-EMF.

you have already tried this so I am at a bit of a loos.

Did you set back-emf to 0?

I had what sounds like the same problem with a Class 20 and an 8245. it was doing my head in and I though

that the issue was mechanical. Setting back-emf to 0 fixed it.

[Fireman_Ian]

What Loco is it? I have the same problem with a Thompson L1 and Hornby told me that the motor is geared to run smoothly at higher speeds not low speeds??????
I tried all the decoder settings aswell but to no avail, so I have a loco which is pretty

much useless.

[markSandD]

It is a Bachmann 7F 2-8-0

Although having took the loco to pieces again for the 3rd time, I think it is a stiff chassis that is causing the problem, as under DC control, the loco needs a bit of a tweek with the control knob to get it moving. I am
currently giving it more 'running in'.

This could be the problem with your loco also?