Husqvarna K7000 Workshop Manual page 8

4
8
MOTOR
Function
Working method
The way in which the high frequency motor works differs signifi-
cantly from a traditional motor with rotor windings and collec-
tor/carbon brushes.
The rotor in the high frequency motor consists of permanent
magnets with high magnetic force, known as neodymium magnets.
In other words, the rotor has no windings or electrical components.
The stator has several field windings. The high frequency unit,
which is connected to the motor, generates a rotating magnetic
field in the stator and the rotor follows this movement.
In comparison with the traditional motor, the rotor and stator
have essentially swapped functions.
The high frequency motor is considerably more efficient than a
carbon brush motor and its output, in relation to its weight, is
significantly higher, which is why it is ideal for handheld machines.
Cooling
The cavity between the stator and the rotor is filled with oil. This
oil leads and distributes the heat out towards the motor housing.
An outer jacket surrounds the motor housing and the space has
channels for cooling water. The photo below shows the structure of
the motor housing and cooling jacket.
During wet cutting, the water passes first through the motor and
then on to the blade guard's spray nozzles.
During dry cutting, the water flow is rerouted so that the water
flows out through the hose located beneath the rear handle after
having cooled the motor. This hose has a Gardena coupling for
connection of an extension hose.
Testing in the workshop
Water does not need to be connected for motor cooling for short-
term testing with the motor without load.
Service actions
The motor will probably not require any service actions during
the service life of the machine. Repairs to this type of motor are
complicated and require both special knowledge and special tools,
and this work is not really of a type which can be carried out at a
regular service workshop. Therefore, a failed motor will be replaced
by a complete new motor.
Turn the gasket the right way
If the gasket is removed, note how this is to be turned when
refitting. Make sure also that the plastic guard rests correctly in the
grooves against the gasket during fitting.
Nipples for cooling water
Two nipples are connected to the motor for the cooling water
supply. New ones are fitted without sealant. (3–4 Nm)
Belt pulley
The belt pulley is removed by locking the rotation using a 19 mm
wrench and removing the centre screw, Torx 27. (M6x30, 10–12 Nm)
Note that there is a supporting ring under the belt pulley.