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wiper brushes

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57_BN4

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Just finishing overhauling the wiper motor and have a question: which way round do the brushes go back in? Does the ribbly end go in the brush holder or the flat end? the old brushes have a flat end so I'm guessing the ribbly bit is designed to wear down quickly to match the armature shape? Anyone got other thoughts on this?

Cheers,
Andy.

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Andy
You want the flat surface to the commutator. It will seat itself shortly. The ribs could cause sparking. Not sure why they put them in.

Marv
 
I'm guessing the ribbly bit is designed to wear down quickly to match the armature shape? Anyone got other thoughts on this?

-------------- :iagree:---------Keoke
 
The wiggly bits are probably to engage the springs that put pressure on the brush.
 
In Electrical motor school we were taught to have as much surface contact as possible to keep arcing down and current flow max.. Brush size designed to cover commutator segments. Will agree with TOC that it probably helps with heat transfer on the brush and not down the brushholder.

Marv
 
The odd thing is that the back of the brush holder has a dimple stamped into the cup that holds the brush and this tends to crush into the ribbles of the brush if they are inserted first. Perhaps that is how they were meant to be. The non OEM brush kit in the pic below doesn't have the ribbles so they can't be that important.

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There aren't any brush springs in the conventional sense, the two arms in the pic are pulled together by the little spring across the middle which cantilevers the arms off their fulcrum point below the armature. You can see the general layout at the top of page 18 here, although it shows a DR1 motor. https://www.justbrits.com/Articles/Lucas08.pdf

I'm tending towards putting the ribbly ends in the holders so the flat ends contact the commutator.

Andy.
 
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