Husqvarna K3600 Mk II Workshop Manual page 39

20
Cause
The gear motor used in the cutting machines is a precision pro-
duct that is manufactured with very small dimensional tolerances
in order to ensure minimal leakage and a high level of efficiency.
Motor damage
The wear damage described above is uncommon. Generally
speaking, there are the following causes:
– The hydraulic motor has operated for many hours beyond that
estimated to be the normal operating life of the machine.
– If wear occurs on a hydraulic motor with fewer operating hours,
the first thing that must be checked is the hydraulic oil.
Hydraulic oil
The quality of the hydraulic oil has considerable bearing on the
lifespan of the hydraulic motor. Contaminants in the hydraulic
oil increases wear significantly. Old oil affords poorer lubrication
characteristics. Incorrect oil quality can also increase wear.
38
INSPECTION
Motor housing/cover
Damaged motor housing
Damaged bearings cause the gears to be positioned obliquely to the sealing
surfaces of both the motor housing and the cover. Damage manifests as
circular grooves following the movement of the gears and leads to reduced
motor power due to internal leakage.
Damaged cover
If the slide bearings in the cover are damaged, wear marks usually appear on
the flat surfaces of the cover facing the flat side of the gears and on the
circular shaped surface that engages with the gears.
Repair or motor replacement
Damaged motor housing/cover – motor replacement
If there is wear damage caused by the gears in the motor housing
or the cover, it is a sign of internal leakage. If motor power is
reduced, the aforementioned damage is probably the cause.
Neither the motor housing nor the cover can be repaired. The
solution is to replace with a new motor assembly.
Replacement of bearings
It is uncommon for loose motor bearings not to have damaged
the motor housing and cover, primarily because the fault symp-
tom manifests once the gears have damaged the sealing surfaces.
Replacing the gear shaft slide bearings is a quite complicated and
unusual procedure. See description below.
This procedure must not be confused with replacement of the
driveshaft roller bearings.
Re-fitting
When re-fitting the cover to the motor housing, all old sealant residues must
be removed and the surfaces degreased.
Sealant
The following types of sealant are tested and recommended:
Henkel Omnifit FD 1042 or Loctite 572. Both sealants are anaerobic, which
means that they harden where there is no oxygen. Spread the sealant in a path
approximately as shown in the picture. Only a very thin string of sealant is
required, 1–2 mm (.04–.08) in diameter.
Fit the cover
Don't forget to fit the main valve spring!
Tighten all screws crosswise and alternately with increased tightening torque
! in order to provide even contact between motor housing and cover.
Final tightening torque: 10 Nm/7 lbf·ft
Use a torque wrench.