BigDog Alpha - Mower Blade Maintenance

REV B 6-4 119293
Blades
Mower blade maintenance
Refer to the Mower blade replacement section for blade
removal and installation.
Check the mower blades daily as they are the key to power
efficiency and well groomed turf. Keep the blades sharp. A dull
blade will tear rather than cut the grass, leaving a brown ragged
top on the grass within a few hours. A dull blade also requires
more power from the engine.
Replace any blade which is bent, cracked or broken.
Sharpen the blades on a grinder following pattern as shown
(Figure 6-11). Touch-up sharpening can be done with a file
Check the blades for balance following grinding. A commer-
cial balancing tool is available through most hardware supply
stores, or balancing can be done by placing the blade on an
inverted line punch or 5/8” bolt. Blade should not lean or tilt.
Spin the blade slowly, blade should not wobble. If blade is out
of balance, true it up before reinstalling.
Lay the blade on a flat surface and check for distortion (Fig-
ure 6-12 & Figure 6-13). Replace any distorted blade.
WARNING
Never attempt to straighten a bent blade by heating, or
weld a cracked or broken blade as the blade may break
and cause serious injury. Replace worn or damaged
blades.
WARNING
Never work with blades while engine is running or deck
clutch switch is engaged (on). Always place deck clutch
switch in the disengaged position, place steering control
levers in the park brake position and turn engine off and
disconnect negative battery cable. Block up mower when
you must work under it. Wear gloves when handling
blades. Always check for blade damage if mower
strikes a rock, branch or other foreign object during mow-
ing!
WARNING
Always wear adequate eye protection when grinding
mower blades.
WARNING
Mower blades are sharp and can cut. Wrap the blade(s) or
wear gloves and use extra caution when servicing them.
Figure 6-11
Figure 6-12
Figure 6-13
Resharpening
pattern
Do not sharpen to original pattern (below). It is
easier to get a straight cutting edge following
the resharpening pattern shown above.
Original edge
Warped Blade (Replace)
Straight Blade
Cutting
plane
Comparison of Warped and Straight Blades
Cutting edge
Twisted Blade Edge
(replace)
Cutting edgeCutting Plane
Straight Blade Edge
End view of blades, comparing
twisted and straightened blades