12v question

[dolph]

dont know if anyone can solve this? I have a HillyBilly golf trolley. It stopped and whilst the company want £69 for a new motor, I took it to pieces and found the carbon bushes had worn right down,

New ones were not available but I found similar on Ebay (Dyson vacuum) rubbed then down to size and fitted them, connecting copper wires together by solder.

The motor now works, but initially it went backwards!!! Changed the wires round, goes other and correct way.

My problem is that whilst the motor spins the wheels well, there is very little torque, and any sort of hill and the motor just cannot cope.

Has anyone have any ideas what can be the problem. I would add before stopping due to the bushes it was fine, however the bushes were rounded to the armature whilst the new ones are still square on the end until of course they wear down, would this make any difference?

 

[big-all]

clamp the trolly in a workmate or some other method where you can observe the commutator and brushes
turn on and see how much it sparks
load up the wheel[ rub somthing against it to slow it down] and check the sparks again

its possible the brushes need bedding in
the springs are not doing there job
the commutator needs cleaning
the motor has one or more segments burnt out
the magnets have become demagnatised
electronics damaged by arcing

 

[wotan]

Yes that would make a considerable difference, the carbon brushes should be contoured to the communtator, the reason being as the armature rotates the brushes should be in contact with two communtator segment at the same time, this ensures smooth rotation as the current flows continuously 'make before break' makes for smooth continiously rotation.
As it is at the moment it's just cogging around, and not developing full power.

Wotan

 

[ericmark]

The material that brushes are made of varies. In a starter motor they have a very high % of copper in mix but for a dynamo there is far more carbon in the mix. Durite sell brushes for 12v stuff and their catalogue does say how hard they are. Too hard (loads of copper) and the armature will wear too quick and too soft and the brush wares too quick. The mica between segments on some motors needs under cutting and on others it is not required again down to hardness of brushes.
Often one needs to use sand paper (glass paper) to bed them in. Don't use emery paper as dust off emery is conductive. There are also com sticks to clean the armature. I have spent many a happy hour with hack saw blade undercutting. Real pain of a job.

So I would guess wrong grade of brush and there is too much carbon in the mix.

I would see if you can find an auto electrician to match you some up. One has a good idea by looking at the colour.

 

[ban-all-sheds]

Don't use emery paper as dust off emery is conductive.

It can be cleaned out, can't it?

Emery is an attractive thing to use as you can get cloth, which forms to the shape of the commutator...

 

[ericmark]

Don't use emery paper as dust off emery is conductive.

It can be cleaned out, can't it?

Emery is an attractive thing to use as you can get cloth, which forms to the shape of the commutator...

To get correct radius the thinner the better so paper is better than cloth. Bits do tend to fly off the paper or cloth and can get lodged but of course the brushes are also made of conductive material so cleaning will always be required but why use emery if not required glass paper is also cheaper.

But the main thing is a 230v motor is likely drawing around 3A and the 12v motor is likely to draw 30A and so unlikely the brushes will be made from same grade of material and although bedding in may help it is unlikely to cure the problem. I would guess he will need a harder brush.

 

[dolph]

Guys what can I say, Many many thanks for your replies, if it rains this week I have plenty of tips that I can try out.

 

[ban-all-sheds]

Just hire a caddy.

 

[Deluks]

Just hire a caddy.

I can see now why so many men take up golf!

Why is one of them dressed as a nurse??

Fave holiday destination: Tiger Woods