Sickly Bullant motor bogies

[whart57]

I have a number of Bullant six wheel motor bogies that are not performing very well. They are so-so on DC but once connected to DCC they are frustratingly bad. They seem to have to have a very high voltage on them to run anything like smoothly, the knob on the DC controller is two-thirds of the way round just for walking pace. Over on DCC that really is bad, I've had to turn off the acceleration option and set a high value for start voltage and the bogies still stop and start.

 

I wonder if part of that is inherent, three worms introduce a lot of friction.

 

Getting the pickups sorted is not easy, and of course that is more friction.

 

The motors run very hot too.

[34theletterbetweenB&D]

I would want to break down the assembly and test each stage to determine the sources of friction and correct as best possible. Small alignment errors of a single worm shaft with three worm and pinion sets can cause a lot of friction as you suspect:

17 hours ago, whart57 said:

...I wonder if part of that is inherent, three worms introduce a lot of friction...

...so while we should never jump to conclusions that would be high up the suspect list. Without knowing the use you make of these bogies one idea would be to remove the centre worm and allow the axle it engaged to float. No significant loss of traction, a third of the worm friction gone.

[whart57]

Up till now I've concentrated on electrical pickup. The bogies are rigid frames so this means that the slightest unevenness in the track causes one end or other of the bogie to lift off the track. Good pick-up across all wheels is essential but amazingly hard to achieve with these bogies. Maybe the 00 versions are better but mine are for 9mm gauge track. The wheels, worm and gear are also on very tight, as I found trying to correct an under gauge back to back, so disabling a worm might not be that simple. I'll give it some thought.