MTD 112-671A - Manual (Page 7)

CAUTION
MAINTENANCE
CUTTING BLADE
A. Removal for Sharpening or Replacement
Be sure to disconnect and ground
the spark plug wire before working
on the cutting blade to prevent
accidental engine starting.
1. Remove the large bolt and lock washer which
holds the blade and adapter to the engine
crankshaft. See figure 8.
2. Remove the blade and adapter from the
crankshaft. Be careful not to lose the key on
the crankshaft.
3. If the blade or blade adapter needs replacing,
remove the two small bolts, lock washers and
nuts which hold the blade to the adapter.
A
CAUTION
Periodically inspect the blade
adapter for cracks, especially if you
strike a foreign object. Replace
FIGURE 8.
B. Sharpening
Remove the cutting blade by following the direc­
tions of the preceding section.
When sharpening the blade, follow the original
angle of grind as a guide. It is extremely important
that each cutting edge receives an equal amount
of grinding to prevent an unbalanced blade. An un­
balanced 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 for balance by balancing
it on a round shaft screwdriver. Remove metal
from the heavy side until it balances evenly. See
figure 9.
■11^ NOTE
It is recommended that the blade
always be removed from the adapter
for the best test of balance.
FIGURE 9.
C. Reassembly
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. Lubricating the bolt holes,
bolts and inner surface of the nuts with light oil is
also recommended. A 4 oz. plastic bottle of light
oil lubricant is available. Order part number
737-0170. Engine oil may also be used.
When replacing the blade, be sure to install the
blade with the side of the blade marked “Bottom”
(or with part number) facing the ground when the
mower is in the operating position. Make certain
key is in place on the crankshaft.
Blade Mounting Torque
3/8" Dia. Bolt 375 In. lb. min., 450 in. lb. max.
5/16" Dia. Bolt 150 in. lb. min., 250 in. lb. max.
To insure safe operation of your unit, ALL nuts
and bolts must be checked periodically for correct
tightness.
DECK
The underside of mower deck should be cleaned
after each period of use as grass clippings, leaves,
dirt and other matter will accumulate. This ac­
cumulation of grass clippings, etc., is undesirable
as it will invite rust and corrosion and may cause
an uneven discharge of grass clippings at the next
cutting.