Berlingo Brushes

[Flying John]

I have just popped out the lower brush tonight to inspect after 190 miles - It has bedded beautifully - This is probably due to the pre-curvature put on by Schunk. They say that the originals are supplied curved to fit the Leroy Somner motor armature. You can see where it has been "rubbed" by the com as it revolves.

So I think they are better than the slotted ones that have to be worn away by the armature before you get full brush contact on the com.


JOhn

[ChrisB]

The genuine ones are still pre-curved but just have grooves in front surface.
I'd think the grooved ones have got to be able to have more contact area quicker than one thats not got the grooves as its got to rub more of the brush surface area away before making full contact I'd think.

Nice to see that they appear to have bedded in mind you so quickly in less than 200 miles

I do wonder if com condition might play quite a major bit in it all as well.

ChrisB

[Flying John]

Aha - I didnt realise some were grooved and curved to the correct shape. The picture I have seen of a grooved one didnt appear to be curved as well. Anyway, I am dead chuffed bacause the first set I replaced a year or so ago were flat ended and I had to try and put a curve on them myself with emery paper before I fitted them.

John

[ChrisB]

Time for another brush change and here are the results

This time I removed the motor fan to give the motor a "blow out" with compressed air, found some interesting marks on the brushes and brush holders

Heres some pics
Cooling fan removed


What you see.........not a lot


Close up


Odd carbon marks on brush cover


The removed brushes, in the order they sit in the motor, i.e top one is top in the motor etc


Note the odd marks on the left and right brushs yet on the top and bottom brushs seem to be not sitting correctly ???









Notice the left and right brushes are showing signs of arcing on the leading edge yet the top and bottom dont ??
The old ones seem to have worn fairly evenly although the bottom and top have worn slightly more.
Anyhow all back together and now got a 100 miles of gentle driving to bed these in.

ChrisB

[Grumpy-b]

When the brushes are low the spring pressure is reduced. As they wear and become shorter the angle change caused by slight and needed looseness in the brush holder will cause the effective rocking of the brush on the commutator to increase. I think these two things together cause the slight sputtering on the brush edge. A newer brush does not have this appearance.
Like many things with experience, it may be that the wear line would be better to be a couple of mm lower down the brush.
Grumpy-b

[Flying John]

How easy was it to get the blower fan off Chris

[ChrisB]

When the brushes are low the spring pressure is reduced. As they wear and become shorter the angle change caused by slight and needed looseness in the brush holder will cause the effective rocking of the brush on the commutator to increase. I think these two things together cause the slight sputtering on the brush edge. A newer brush does not have this appearance.
Like many things with experience, it may be that the wear line would be better to be a couple of mm lower down the brush.
Grumpy-b

Ah yes could be, as you say as they drop down the brush holder the spring tension gets less, still seems odd that only two are showing the signs of one type of wear and two are another type

Going to keep this old set a spare as theres still some life left in them.

ChrisB

[ChrisB]

How easy was it to get the blower fan off Chris

Cooling fan is very easy , three nuts, two on the inner wing and one down by the fan outlet (front of vehicle) disconnect the lead to the motor and the lead to the relay thing on the side of the motor and lift out the cooling fan.

ChrisB

[sparky]

Notice the left and right brushes are showing signs of arcing on the leading edge yet the top and bottom dont ??
The old ones seem to have worn fairly evenly although the bottom and top have worn slightly more.
ChrisB

That's interesting when I change my brushes the old ones looked exactly the same as yours with the left and right showing signs of arching,
my original brushes lasted 18,000 miles, now I'm on my third set this year as I'm only getting 3,000 miles a set.
I jacked the front up removed the brush cover and got someone to run up the motor while I observed the brushes below 30 mph there's no arcing above 30 all the brushes begin to arc the faster I go the more it arcs.
With it being a dc motor two brushes will pick up material while the other two will deposit material when arcing.
That's why only two shows signs of arcing my commutator looks fine and it arcs with new brushes fitted and bedded in ?.

[ChrisB]

Notice the left and right brushes are showing signs of arcing on the leading edge yet the top and bottom dont ??
The old ones seem to have worn fairly evenly although the bottom and top have worn slightly more.
ChrisB

That's interesting when I change my brushes the old ones looked exactly the same as yours with the left and right showing signs of arching,
my original brushes lasted 18,000 miles, now I'm on my third set this year as I'm only getting 3,000 miles a set.
I jacked the front up removed the brush cover and got someone to run up the motor while I observed the brushes below 30 mph there's no arcing above 30 all the brushes begin to arc the faster I go the more it arcs.
With it being a dc motor two brushes will pick up material while the other two will deposit material when arcing.
That's why only two shows signs of arcing my commutator looks fine and it arcs with new brushes fitted and bedded in ?.

Interesting, I'm a little unclear why only two brushes show signs of copper pick up, I wondered if it was because two are used for regen ?? but then as theres only two connections onto the brush ring that rules that one out.

Slight concerned that your doing a set of brushes in 3K with similar signs, must admit I have an idea the original brushes I bought the van with where original as they were dated the same as the van and that had done 20k ( although they where down to the braid almost ) this set have done nearly about 10k I recon and still have life left in them BUT I do think I've been doing higher speeds than when the van was orginally owned it use to roam about Westminster in its day so doubt it ever exceeded 30mph, today quite often it will do 12 to 20 miles on a trip at 50-60 mph down the motorway, so dont know if thats anything to do with it.

I've read somewhere that the brushes actually float on a plasma at speed and hence you will get arcing when its running fast, dunno how true that is mind you ??

ChrisB