Husqvarna K3600 Mk II Workshop Manual page 35

18
Symptom: Motor does not stop – control in stop position
Cause:
Deformed link rod
Dirt locking the torsion plate
The servo valve, on which the torsion plate is mounted, has a
very definite position where the servo valve is open to the return
side, which in turn allows the main valve to be open to the return
side. The motor is inoperative in this position.
This may be due to a bent link rod. Dirt or a defective return
spring at the torsion plate may also prevent the servo valve
reaching the stop position (open servo valve).
Blocked servo valve
When the main valve is in bypass position (stop position), a
small amount of oil comes through the small hole in the main
valve hat and into the servo valve channels to the return side.
Blocked channels in the servo valve have the same effect as an
activated starter, i.e. the motor runs.
Locked main valve
Once the hydraulic unit is shut off, the main valve is compressed
into operating position by the spring above. If the machine has
not been used for some time, it is likely that the main valve has
locked in this position.
Leaking main valve
The following faults may cause sufficient leakage to prevent the
main valve opening to the return side:
– Damaged gasket around the main valve
– Bad seal between the main valve and the white plastic hat.
Alternatively, the plastic hat may be deformed or leaking.
.
Symptom: External leakage
Cause:
Motor housing/cover
Leaks between the motor housing and the cover may occur with -
out there being any other fault.
Driveshaft
The sealing ring to the driveshaft is exposed to wear. If oil leakage
occurs here, the sealing ring must be replaced. If the shaft is
damaged by the sealing ring, it must be replaced. Whilst doing
this, check the integrity of the driveshaft roller bearings. Bearing
play causes damage to both the sealing ring and the slide bearings
in the motor housing and the cover. Running the machine for
extended periods of time with damaged drive disc bearings will
lead to the hydraulic motor suffering irreparable damage.
34
TROUBLESHOOTING – PROCEDURES
Action:
This test is to be done with the cutting machine connected to a
hydraulic unit. For safety reasons, remove the cutting machine
blade.
K3600 MkII: Remove the handle half in order to make the
starter link rod accessible.
With the hydraulic unit in operation: Using a pair of pliers,
press the link rod to the stop position.
K2500: Remove the front and rear belt guards and the belt.
With the hydraulic unit in operation: Using a pair of pliers,
force the torsion plate to the stop position.
If doing this does not produce results, the hydraulic motor must
be examined. Disconnect the machine from the hydraulic unit.
Remove the servo valve and blow the channels (two holes on
either side of the shaft) and the channels in the motor housing
clean. See page 46.
Remove the hydraulic motor cover and check the movement of
the main valve.
Remove the main valve and examine the units for potential leaks.
Action:
Remove the cover from the motor housing and examine the
sealing surfaces. If there is no fault, carefully remove oil and
sealant residues from the sealing surfaces. Spread on fresh sealing
compound and re-fit. Tighten the screws alternately and to the
correct tightening torque.
Remove the driveshaft from the motor housing. First check
whether the leak comes from the inner sealing ring (to the shaft),
then check whether it comes from the outer sealing ring (to the
motor housing).
Check the integrity of the shaft roller bearings. Play in the roll-
ler bearings may be an indirect factor in the sealing ring to the
driveshaft being damaged.
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