Valves - Husqvarna K3600 Mk II Workshop Manual

VALVES

Main valve
Function
The main valve manages the start and stop function of the hydraulic motor
by guiding the oil flow to the gears or the return side. The position of the
main valve is dictated by the servo valve, which is directly connected to the
start control.
Important for the function
The main valve must be able to move without hindrance and the sealing rings
must be intact. It is very important that the small hole in the centre of the
plastic hat is open. If it is blocked, the motor will not start. It is also impor-
tant that the plastic hat is kept in position relative to the main valve (by the
O-ring) with a certain amount of resistance.
Removal
Remove the spring and lift the
valve.
Inspection
Lift the plastic hat off and check
that the piston is free from cor -
rosion and dirt.
Check the O-rings.
The smaller O-ring must hold
the plastic hat in position.
Check that the plastic hat is
intact and that the hole in the
centre is open.
Check the condition of the
spring.
Check piston movement
Place the main valve in position
and press it down into its bore
so that approximately 5 mm/
.2 in. remain until it bottoms.
Using the power of the spring, it
should now be possible to move
the piston to its bottom posi-
tion.
Removal
Remove the coiled spring from the main
valve.
Lift the valve with a twisting motion
using a pair of circlip pliers.
Inspection
Lift the plastic hat off and check that the
piston is free from corrosion and dirt.
Also check that the bore for the piston
in the motor is free from damage and
contaminants.
Check that the O-rings are intact.
It is important that the smaller O-ring
holds the plastic hat in position with a
certain amount of resistance. Otherwise,
replace the O-ring or plastic hat.
Check that the plastic hat is intact and
that the hole in the centre is free from
contamination.
Check that the spring is intact, i.e. free
from corrosion and fatigue.
Check piston movement
Place the main valve assembly in position
and press it down into its bore so that
approximately 5 mm/.2 in. remain until
it bottoms. Using the power of the
spring, it should now be possible to
move the piston to its bottom position.
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