Honda HRM 520 Owner's Manual page 70

Maintenance procedures
Checking the blades and blade disc
Check the condition of the blades and blade disc as follows.
Life time of the blades
In order to have good cutting performance, maintain the sharp cutting edge on the blades. Typically, the life
time of the blades is 160 hours.(2 weeks to 2 months) Because the life time depends on grass condition, it
may be necessary to exchange earlier than usual, especially in the spring season.
If your lawn will become the condition of white fiber it is a sign to change blades.
Example: if the lawnmower works for 11.4 hours per day every day, the life time of the blades is 2 weeks.
If the lawnmower works for 2.6 hours per day every day, the life time of the blades is 2 months.
N WARNING
- Do not touch the blades with your hands.
- Make sure to press the manual STOP button and turn the lawnmower off before performing the
following procedures.
NOTE:
- Hold the lawnmower against a wall for support.
- Do not lift the lawnmower off of the ground while checking it.
Check the blades, nuts and blade disc for problems.
Blades and nuts
Blade disc
Blade disc
Base of the blade
Normal
68
Check item(s)
Damage to the blades
Loosened bases of the
blades
Abrasions of the holes of
blades and abrasions of the
shoulders of nuts
Warping of the blade disc
Checking the abrasions of
blades and nuts
Damaged blades
Excessively worn
Visually inspect the blades.
If they are damaged, replace the blades. See
"Replacing the blades" (M page 69).
Rotate the nuts with your finger to check that they are
not loose.
If the nuts are loose, tighten them to the specified
torque value. See "Replacing the blades" (M page 69).
Visually inspect the abrasions of the hole of blades
and the abrasions of the shoulder of nuts.
While mowing, the hole of the blades will widen and
the shoulder of the nuts will decrease in size because
of abrasions, and there is a danger that the blades will
be detached from the blade disc.
If they are worn, replace the blades and nuts. See
"Replacing the blades" (M page 69).
Rotate the blade disc and visually check it.
If it is warped, consult your dealer.
22.2mm 25.2mm
Correct Incorrect
Cracked Bent
Action
Checking the abrasions of
the shoulders of nuts
Correct Incorrect