Jerky running down gradients

[brunel]

Hello As an 00 gauge Southern modeller, this is my first visit to the forum, so best wishes to all. I find that some locos and EMUs run erratically down gradients, the controller seeming to sense the train's running away and slowing it then letting it go again and so on. This is the same with both the Vector and the H&M controller. Should I just reduce the gradient (difficult in confined space) or is there an electronic solution please?? Thanks for any advice.

[Barry Ten]

American modellers encountering this problem seem to get around it by eliminating all slack in the gear train, using thrust washers. They're normally working with centrally mounted motors, transmission to both bogies etc. Not sure if that would be possible to arrange with your mechanisms?

[Grovenor]

As Barry Ten says this effect is caused by mechanical problems in the gears and can't be fixed by the controllers. Essentially the train is trying to go faster than the motor and hence drive the gears in reverse, as our worm gears don't work in reverse they act as brakes then as the train slows they will free off again allowing the train to accelerate then repeat the process. One solution is just to go down the hill a bit faster

If that's not practical for you look at the gears, you will usually see that the worm has quite a bit of fore and aft movement, if you can fit thrust washers either end of the worm to minimise that movement you will reduce the effect.

Keith

[bertiedog]

As per other posters, it is play in the drive, but in fact a controller can help, as long as it's a full feedback type, preferably with selectable rates, as the motor tries to race, it is cut back, and as it drags it will remain at the right speed. The effect is relative, it reduces it, but not eliminate it entirely.

 

 

Adding grease to the gears can help, especially with spur gear bogies, but use proper grease like Labelle, safe with plastics.

 

Other than that, a speed restriction will be needed on these gradients! or the gradients eased.

 

Stephen.

[brunel]

Thanks for the advice. The thrust washers and grease have helped quite a bit, so thanks.