163. Precautions
a. Always keep the chain saw well lubricated (par. 165a).
b. Be sure to blow out the air hose before connecting it to the air connection.
c. Operate the saw only at recommended air pressure. Less than 80 psi will result in loss of power; more than 100
psi will cause undue wear of moving parts.
d. Be sure to keep the air inlet strainer clean.
e. Keep the chain properly sharpened at all times. Chains should be "touched up" with a file after every 4 hours of
continuous operation. Do not attempt to remove much metal, and maintain the original cutting angles (bevels) on all
cutting edges.
f. Always detach the air hose from the air connection when stopping operations for any length of time. Then brush
the chain with OE, engine oil.
164. Operation
a. Normal Operation. The bumper, which is the part of the drive housing fastened to the saw plate, must be placed
and held against the log before the teeth begin cutting. The saw guide must be kept in the middle of the cut so that the
teeth returning in the upper groove do not cut into the sides of the kerf. Feed the saw into the timber slowly. The rate of
feed will depend on the kind and size of timber. When making a deep cut, the saw slot should be spread with a wedge to
prevent pinching of the guide bar and chain saw. Many times it will be found possible to cut faster if operators advance
their ends separately. Do not expect to cut fast with a dull chain. Sharpen or "touch up" the chain at least every 4 hours of
continuous operation.
b. Tree Felling. Turn the saw to cut down at an angle of about 30 from the horizontal. Make a cut at this angle on
the falling side of the tree in about one-fourth to one-third of its diameter. Then make a horizontal cut in to meet the end of
the angle cut. Remove the cutout piece. Make a horizontal cut on the opposite side of the tree about one-quarter of the
tree diameter above the cutout wedge. As soon as the tree inclines, remove the saw a safe distance away. When felling
heavy trees, it may be advisable to insert a wedge in the cut.
c. Underwater Cutting. For underwater cutting, remove the 3/4-inch pipe plug under the dead handle and screw this
plug into the exhaust port near the sprocket. Install at 3/4-inch standard 45 street elbow and an exhaust hose or pipe into
the exhaust port. The exhaust hose or pipe must be of sufficient length to reach above the surface of the water. If the cut
is being made
155
