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Carbon brush problem

T

Ted Edwards

Jan 1, 1970
0
My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

Ted
 
A

Adrian Tuddenham

Jan 1, 1970
0
Ted Edwards said:
My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

Have you got starter brushes or just any old brushes?

The reason I ask is because starter brushes are often made much more
conductive than ordinary brushes because of the huge currents they
handle. The carbon is heavily loaded with powdered copper and they have
a slightly coppery appearance, compare the new brushes with the remains
of the old ones to see if this is the case.

If you use ordinary brushes when coppery ones are needed, you may not
get enough starting current through the motor and you may burn the
commutator.
 
A

Andrew VK3BFA

Jan 1, 1970
0
Adrian said:
Have you got starter brushes or just any old brushes?

The reason I ask is because starter brushes are often made much more
conductive than ordinary brushes because of the huge currents they
handle. The carbon is heavily loaded with powdered copper and they have
a slightly coppery appearance, compare the new brushes with the remains
of the old ones to see if this is the case.

If you use ordinary brushes when coppery ones are needed, you may not
get enough starting current through the motor and you may burn the
commutator.
 
T

Ted Edwards

Jan 1, 1970
0
Adrian said:
Have you got starter brushes or just any old brushes?

Starter brushes - lot's of copper content.

Ted
 
K

Klaus Bahner

Jan 1, 1970
0
My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

Hi Ted,

I once replaced brushes for an automotive starter motor years ago. The
spares came without leads, just the mounting hole. According to the
manufacturer the leads should just be soldered to the brushes. Put the
lead ends into the holes, then solder them to the brushes with regular
solder. Depending on the brush size use a 60 - 100 W solder iron.

Klaus
 
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