Carbon Brushes - Husqvarna DM 230 Workshop Manual

8
Max 10 mm
1
3
5
14

CARBON BRUSHES

2
4
6
Replacing the carbon brushes
The two carbon brushes transfer electric current to the motor's rotor. A cable
from the stator is connected to the screw in the holder. The carbon brush
cable is connected to the same screw.
The carbon brushes are wear parts that must be checked regularly. Every
week if the machine is used on a daily basis.
You should replace the carbon brushes when around half is left. You can
easily measure this using a slide gauge without removing the brushes. Replace
the carbon brushes when the distance from the brush holder to the top level
of the brush exceeds 10 mm (.4 inch).
Worn carbon brushes – checking
The importance of replacing the brushes in good time is demonstrated by the
adjoining illustrations.
The illustrations to the left show a brush that is worn but still operable.
Both brushes and the collector have minor scratches in the direction of rota-
tion which is entirely normal.
The illustrations to the right show the results when the brush is so worn
that the spring, which presses the collector down, has reached its end position
and no longer gives the brush the correct pressure to the collector. Sparking
occurs which damages both brushes and, even worse, the collector in a very
short time.
Pay careful attention to sparking near the collector
If the brushes are not worn, sparking could be due to the brushes being
unable to move in their holders as a result of, for example, dirt.
Replacing the carbon
brushes
1. Remove the screws
2. Lift off the cover.
3. Loosen the screw one turn.
4. Pull out the cable lug
5. Lift the spring and pull out
the carbon brush.
6. Let the spring rest in the
holder and clean it.
Carbon brush holder
Remove the carbon brushes.
Remove the circuit board screw
and fold this to the side. The
screws are now accessible.
Replacing the carbon
brushes
1. Remove the inspection cover's three
screws.
2. Lift off the cover.
3. Loosen the screw and screw it in one
turn. Let the screw remain in place.
4. Pull out the cable lug from the screw.
5. Lift the spring with a hook that is tur-
ned as shown in the illustration to avoid
any risk of the spring sliding outside the
carbon brush holder. Lift off the carbon
brush.
6. Let the spring rest in the holder and
clean off any carbon particles and dirt.
Carbon brush holder
You do not need to remove the rotor to
replace the carbon brush holder.
Remove the carbon brushes. Remove
the screw to the circuit board and fold
this to the side enabling access to the
screws (arrows) to the holders.
Note that the cable lug to the carbon
brush must be closest to the holder and
the cable to the stator on top.