Service - MTD Yard-Man 12A-559K401 Operator's Manual

SECTION 9: SERVICE
BladeCare
Periodically inspect the blade adapter and pulley for
cracks, especially if you strike a foreign object. Replace
when necessary.
WARNING: When removing the cutting
blade for sharpening or replacement,
protect hands by using heavy gloves or a
thick rag to grasp the cutting blade.
Disconnect spark plug wire from spark plug.
Turn mower on its side making sure that the air filter
and the carburetor are up.
To RemoveBlade:
Remove the bolt and bell washer which hold the
blade-pulley assembly to the engine crankshaft.
See Figure 12. Remove the assembly from the
crankshaft.
Remove the two bolts and lock nuts from the blade
assembly.
Remove the blade from the blade adapter and
pulley.
To ReplaceBlade:
Before reinstalling the blade-pulley assembly to the
unit, lubricate the engine crankshaft and the inner
surface of the blade adapter with light oil or engine
oil.
Also lubricate the bolt holes, bolt and the inner
surface of the nuts.
Install the blade adapter on the pulley with the "star"
away from the pulley. See Figure 12.
Lock Nut Pulley
-,_ / Assembly
Blade ee [_ee ,,---- Lock Nut
Adapter. _
_,_ Blade
Hex Bolt
_=x Bolt
Bell _x Bolt
Washer
Figure 12
Place the new blade on the blade adapter with the
side marked bottom (or with part number) facing
away from the adapter.
Secure the blade to the assembly with two hex
bolts and lock nuts. Tighten the hex bolts to the
recommended torque. Refer to 'Blade Mounting
Torque' section on this page.
Install the blade assembly on the crankshaft.
Secure with the hex bolt and bell washer (cupped
side of washer to blade) and tighten to the
recommended torque. Refer to 'Blade Mounting
Torque' section on this page.
IMPORTANT: The bolt used to secure the blade to the
engine is specially heat-treated. Do not substitute. To
order replacement bolt, refer to the parts list in the back
of this manual.
WARNING: To ensure safe operation of
your unit, all nuts and bolts must be
checked periodically for correct tightness.
To SharpenBlade:
The blade can be sharpened with a file or on a
grinding wheel. Do not attempt to sharpen the
blade while it is still on the mower.
Follow the original angle of grind as a guide. Make
sure that each cutting edge receives an equal
amount of grinding to prevent an unbalanced blade.
NOTE: An unbalanced blade will cause excessive
vibration when rotating at high speeds, may cause
damage to the mower and could break, causing
personal injury. Test the blade by balancing it on a
round shaft screwdriver or a blade balancer.
If the blade is not balanced, remove metal from the
heavy side until it balances evenly.
BladeMounting Torque:
Blade adapter bolts: 120 in.lbs, minimum, 150
in.lbs.maximum Center bolt: 450 in.lbs, minimum, 600
in.lbs, maximum.
Replacing D rive Belt
Remove the two shoulder screws from on top of the
deck which secures the front drive cover to the
mower deck. See Figure 13.
Remove the front drive cover from the unit by lightly
pressing inward on the sides of the front drive
cover. This will release the tabs that secure the
front drive cover to the height adjuster brackets.
Remove the idler and related hardware from the
idler bracket using 7/16" wrench and socket. See
Figure 13.
Remove the belt from the transmission pulley as
shown in Figure 14.
Lift and stabilize the front of the deck.
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