Troubleshooting - Procedures - Husqvarna K3600 Mk II Workshop Manual

Symptom: Low motor output
Cause:
Worn motor
Internal leakage allows hydraulic oil to pass the top and bottom
side of the gears due to wear. This sort of wear can be totally
normal for a motor that has had a long operating life. Incorrect,
old or contaminated hydraulic oil will increase wear dramatically.
Leaking main valve
If the main valve does not fully close in operational position,
some of the oil will pass directly to the return side.
Symptom: Motor does not start
Cause:
Locked main valve
Once the hydraulic unit is shut off, the main valve is compressed
into operating position by the spring above. When the hydraulic
unit is started, the main valve is forcibly compressed to the
spring. The reason why the motor does not start may be that dirt
or corrosion prevent the spring from compressing the main valve
into operational position. If the machine has not been used for
some time, this may be the main reason for the motor not
starting.
Blocked valve hole
If the valve hole (the main valve white plastic hat) is blocked,
pressure will not be equalised on both sides of the main valve –
the piston will stop in bypass position.
Locked gear
It is very unlikely that this is the cause of the fault.
Defective control or link rod
Locked brake valve
The brake valve is locked in bypass position. It is very unlikely
that this is the cause of the fault.
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TROUBLESHOOTING – PROCEDURES
Action:
Connect the machine to a hydraulic unit and test run the cutting
machine with the motor shaft locked in accordance with the
description on the previous page. If the internal leakage exceeds 7
litres per minute/2 gpm, the hydraulic motor must be repaired.
Remove the hydraulic motor cover and inspect for signs of
wear damage. If the gears have caused circular grooves and pitting
in the sealing plane, the entire hydraulic motor must be removed
and replaced with a new one. It is also likely that the gear shaft
bearings are worn out.
Remove the hydraulic motor cover and examine the main valve:
– Check that the main valve can move in its bore and does not
jam due to contamination or corrosion and that the O-ring is
intact.
– Also check that the small hole in the main valve hat (white
plastic) is open. Check that the O-ring holds the hat in position.
Action:
Remove the hydraulic motor cover.
Check that the main valve can move in its bore under spring
power and does not jam due to contamination or corrosion.
Check that the small hole in the main valve hat (white plastic) is
open.
Test that the gears can rotate by hand.
This can be checked simply by pressing the starter and noting
whether the servo valve moves.
Disconnect the pressure pipe from the motor. Using a Philips
screwdriver, check that the brake valve can move. Otherwise,
remove the brake valve and spring and check for dirt and
corrosion.
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