Dolmar MS-250.4 - Manual (Page 17)

16
NYLON CUTTING HEAD
The nylon cutting head is a dual string trimmer head capable of both automatic
and bump & feed mechanisms.
The nylon cutting head will automatically feed out the proper length of nylon
cord by the changes in centrifugal force caused by increasing or decreasing
rpms. However, to cut soft grass more efficiently, bump the nylon cutting
head against the ground to feed out extra cord as indicated under operation
section.
Operation
– Increase the nylon cutting head speed to approx. 6,000/min.
Low speed (under 4,800/min) is not suitable, the nylon cord will not feed out
properly at low speed.
– The most effective cutting area is shown by the shaded area.
If the nylon cord does not feed out automatically proceed as follows:
1.
Release the throttle lever to run the engine idle and then squeeze the
throttle lever fully. Repeat this procedure until the nylon cord feeds out to
the proper length.
2. If the nylon cord is too short to feed out automatically with the above
procedure, bump the knob of the nylon cutting head against the ground to
feed out the nylon cord.
3. If the nylon cord does not feed out with procedure 2, rewind/replace the
nylon cord by following the procedures described under “Replacing the
nylon cord”.
Replacing the nylon cord
– First, stop the engine.
– Press on the housing latches inward to lift off the cover, then remove the
spool.
– Hook the center of new nylon cord into the notch in the center of the spool,
with one end of the cord extending about 80mm (3-1/8") more than the other.
Then wind both ends firmly around the spool in the direction of the head
rotation (left-hand direction indicated by LH and right-hand direction by RH
on the side of the spool).
– Wind all but about 100mm (3-15/16") of the cords, leaving the ends tempo-
rarily hooked through a notch on the side of the spool.
– Mount the spool in the housing so that the grooves and protrusions on the
spool match up with those in the housing. Keep the side with letters on the
spool visible on the top. Now, unhook the ends of the cord from their
temporary position and feed the cords through the eyelets to come out of the
housing.
Most effective cutting area
Idle speed Full speed
Knob
Cover
Latches
Press
Press
80mm(3-1/8”) Spool
For left hand rotation
Spool
100mm(3-15/16”)
Notches
Eyelets