User manual
2014
Felling Grapple GMT 035
27
Adjusting the valves
- Out of precaution reasons it’s advisable to perform the adjustments with two persons.
Valve 1
This valve switches the function from closing grapple into sawing. So this valve makes
sure how high the pressure in the grapple cylinder is going to be, before it will switch into
the saw function. The value is dependent of the work pressure from the basic machine and
to be measured at measuring point K on the valve block (see page 22). When correctly
adjusted, the pressure should be 20 bars lower than the work pressure of the basic
machine.
Settings as follows; turn in the valve a few strokes, so when operating the function grapple
close at maximum, the chain doesn’t begin to spin. Now each time turn out this valve a
little, while closing the grapple until the saw gets his maximum RPM ‘s.
Valve 10
This valve switches the function from opening grapple into felling position of the grapple
(tilt up). While the tilt up function may only income when grapple open is maximum
operated, this valve must be adjusted as valve 1, approximately 20 bars lower than the
work pressure of the basis machine.
Settings as follows; turn in the valve a few strokes, so when operating grapple open at
maximum, this won’t come into tilt up position. Now each time turn out this valve a little,
while opening grapple until this comes into tilt up position.
Valve 6
This valve makes sure that the tiltframe only goes back into normal grapple position (tilt
down) when the saw bar is back into the casing. When this valve is turned in to much, the
tiltframe will go back into tilt down position while the saw process is still going on. When
turned out to much, the tilt frame won’t go back into tilt down position at all.
Settings al follows; Make sure that valve 7 is already adjusted correctly. Now fully unscrew
this valve and put the grapple into tilt up position (opening grapple maximum). Now make
a saw movement (grapple close) and turn in valve 6 until the tiltframe goes back into tilt
down position. When going back into tilt down position won’t go correctly, simply turn in the
valve a little bit more.
Valve 7
This valve determines the speed from the grapple going into tilt down position. As soon as
the function grapple open won’t be operated any longer, the tiltframe slowly goes back into
tilt down position. This valve is adjustable at personal preference of the operator.
Settings as follows; Turn in the valve until the stop. Now operate the tilt up function
(grapple open). The grapple won’t go back into tilt down position because of the setting of
the valve. Now turn out the valve until the wanted tilt down speed is achieved. Tip, for thin
wood, a high tilt down speed. For thicker wood, a lower tilt down speed.