MTD Series 430 Thru 439 Lawn Mower User Manual


 
13
SECTION 7: SERVICING YOUR MOWER
Blade Care
Periodically inspect the blade adapter and pulley for
cracks, especially if you strike a foreign object. Replace
when necessary.
Disconnect spark plug wire from spark plug.
Turn mower on its side making sure that the air filter
and the carburetor are up.
Remove the bolt and blade support or bell washer
which hold the blade and adapter to the engine
crankshaft. See Figure 13. Remove the blade and
adapter from the crankshaft.
Figure 13
To Sharpen Blade:
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.
The blade can be tested by balancing it on a round
shaft screwdriver. See Figure 14. Remove metal
from the heavy side until it balances evenly. It is
recommended that the blade always be removed
from the adapter for the best test of balance.
Figure 14
Before reassembling the blade and the blade
adapter 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, bolts
and inner surface of the nuts.
Install the blade adapter on the crankshaft with the
“star” away from the engine. Refer to Figure 13.
Place the blade with the side marked bottom (or
with part number) facing away from the adapter.
Align the blade bell support over the blade with the
tabs in the holes of the blade and insert the hex
bolt. Tighten the center bolt to 450 in. lbs. min., 600
in. lbs. max.
IMPORTANT:
To ensure safe operation, all nuts and
bolts must be checked periodically for correct tightness.
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.
Blade Adapter
Blade
Blade
Bell
Support
Hex Bolt
1. Insert screw driver through hole
2. Blade should be parallel to ground
Screw
Driver
Ground
Blade