Maintenance; Replacing The Bar And Chain; Adjusting The Chain Tension - Ryobi RCS4640N Manual

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1. Underbuck the branch 1/3 through for your first cut (A).
2. Overbuck the branch to drop it (B).
3. Finish by cutting smoothly and neatly against the main
member (C) so the bark will grow back to seal the
wound.
If the limbs to be pruned are above chest height, hire a
professional to perform the pruning.
CUTTING SPRING POLES
See figure 37.
A spring pole (A) is any log, branch, rooted stump, or
sapling which is bent under tension by other wood so that
it springs back if the wood holding it is cut or removed.
On a fallen tree, a rooted stump has a high potential of
springing back to the upright position during the bucking
cut to separate the log from the stump. Watch out for
spring-poles; they are dangerous.
Spring poles are dangerous and could strike the
operator causing the operator to lose control of the
chainsaw. This could result in severe or fatal injury to
the operator.

MAINTENANCE

REPLACING THE BAR AND CHAIN

See figure 3. See figure 38 - 47.
Never start the engine before installing the guide bar,
chain, drivecase cover, and clutch drum. Without all
these parts in place, the clutch can fly off or explode,
exposing the user to possible serious injury.
To avoid serious personal injury, read and understand
all the safety instructions in this section.
1. Always place the switch in the stop "O" position before
you work on the saw.
2. Make sure the chain brake is not set by pulling the
chain brake lever/hand guard towards the front handle
to the run position.
3. Wear gloves when handling the chain and bar. These
components are sharp and may contain burrs.
English (Original Instructions)
WARNING
WARNING
DANGER
WARNING
4. Remove the bar mounting nuts (B) using a combination
wrench (C) or a 13mm socket wrench spanner.
5. Remove the clutch cover (D).
6. Lay out the new saw chain in a loop and straighten any
kinks. The cutters should face in the direction of chain
rotation. If they face backwards, turn the loop over.
7. Place the chain drive links into the bar groove.
8. Position the chain so there is a loop at the back of
the bar.
9. Hold the chain in position on the bar and place the loop
around the sprocket (J).
10. Fit the bar flush against the mounting surface so that
the bar studs (P) in the chassis are in the long slot of
the bar.
11. Replace the clutch cover ensuring that the adjusting
pin (L) in the clutch cover is in the bar tensioning pin
hole and that both bar studs (P) are in their respective
holes (K) in the clutch cover.
NOTE: The adjusting pin (L) may need to be slightly
repositioned with the chain tensioning screw so that it
is aligned with the position of the bar chain tensioning
pin hole.
12. Replace and finger tighten the bar mounting nuts. The
bar must be free to move for tension adjustment.
13. Remove all slack from the chain by turning the chain
tensioning screw (M) clockwise until the chain seats
snugly against the bar with the drive links in the bar
groove.
14. Lift the tip of the guide bar up to check for sagging (N).
15. Release the tip of the guide bar and turn the chain
tensioning screw (M) 1/2 turn clockwise. Repeat this
process until sagging does not exist.
16. Hold the tip of the guide bar up and tighten the bar
mounting nuts (B) securely.
The chain is correctly tensioned when there is no sagging
on the underside of the guide bar, the chain is snug, but
can be turned by hand without binding. Ensure that the
chain brake is not set.
NOTE: If chain is too tight, it will not rotate. Loosen the
bar nuts slightly and turn the tension adjuster 1/4 turn
anticlockwise. Lift the tip of the guide bar up and retighten
the bar nuts securely. Ensure that the chain will rotate
without binding.

ADJUSTING THE CHAIN TENSION

See figure 48 - 50.
Never touch or adjust the chain while the motor is
running. The saw chain is very sharp. Always wear
protective gloves when performing maintenance on the
chain.
12
WARNING

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