MTD 112-638A - Manual (Page 12)

1. Remove the large bolt and lock washer which
holds the blade and adapter to the engine
crankshaft. See figure 21.
■»
FIGURE 21.
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.
FIGURE 22.
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 oii may also be used.
When replacing the biade, 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.
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 22.
NOTE
It is recommended that the blade
always be removed from the adapter
for the best test of balance.
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 the mower deck should be
cleaned after each period of use as grass clip­
pings, leaves, dirt and other matter will ac­
cumulate. This accumulation of grass clippings,
etc., is undesirable as it wili invite rust and corro­
sion and may cause an uneven discharge of grass
clippings at the next cutting.
The deck may be cleaned by tilting the mower for­
ward or on its side and scraping clean with a
suitable tool or by washing with a stream of water
from a garden hose.
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