Craftsman 247.77638 Operator's Manual page 17

5. Rotate impeller assembly by hand until you locate one of two
chipper blades in the chipper chute opening.
6. Remove the blade by removing the internal hex screws, lock
washers, and hex nuts which secure it to the impeller. Retain the
hardware. See Figure 15.
NOTE: Use a 3/16" hex key (Allen) wrench on the outside of the blade
and a 1/2" box (or socket) wrench on the inside of the impeller. Hold
the Allen wrench stationary and rotate the box (or socket) wrench to
loosen the nut.
7. Install a replacement blade (Part No. 742-0544) with the hardware
removed earlier or sharpen and replace existing blade.
IMPORTANT: When sharpening the blade, protect hands by using
gloves. Follow the original angle of grind and make sure to remove an
equal amount from each blade.
8. To replace the other blade, rotate the impeller to expose the
second blade and repeat the steps above.
NOTE: Make certain blades are reassembled with the sharp edge
facing the same direction as when removed. Torque hardware to 250
- 300 in. lbs.
Warning
The impeller's chipper blades and shredder blade are sharp. Wear
leather work gloves to protect your hands.
SHarPEning Or rEPlacing THE
SHrEDDEr blaDE
1. Stop the engine and make certain that all moving parts have
come to a complete stop.
2. Disconnect the spark plug wire and ground against the engine.
3. Lower the hopper assembly and place a block under the flail housing.
4. Remove the six hex lock nuts and flat washers from the weld
studs on the flail housing. Retain the hardware.
SERVICE AND MAINTENANCE
Impeller
Chipper Blade
Figure 15
5. Carefully separate the hopper assembly from the impeller as-
sembly and remove the shredder plate. The shredder plate can be
identified by referring to item 29 in the parts list on page 20 & 21.
NOTE: When reassembling the shredder plate, make certain the
embossed tab faces inward towards the impeller.
6. Remove the two wing knobs that secure the chute deflector and
raise the chute.
7. Insert a 1/2" or 3/4" diameter pipe through the flail screen into the
impeller to keep it from turning or remove the flail screen and
insert a piece of wood into the chute opening.
8. A. Remove the two internal hex screws, lock washers, and hex
lock nuts which secure the shredder blade to the impeller.
B. Remove the hex bolt, lock washer, and flat washer to
completely free shredder blade. See Figure 16.
Weld Studs
A
B
Flail Housing
9. Install a replacement blade (Part No. 742-0544) with the hardware
removed earlier or sharpen and replace existing blade.
IMPORTANT: When reassembling the shredder blade, tighten center
bolt to between 550 and 700 in.-lbs. and the two outside bolts to
between 250 and 350 in.-lbs.
NOTE: Use a 3/16" hex key (Allen) wrench on the outside of the
shredder blade and a 1/2" box (or socket) wrench on the inside of the
shredder blade. Hold the Allen wrench stationary and rotate the box
(or socket) wrench to loosen the nut. Use caution when removing the
blade to avoid contacting the weld studs on housing.
IMPORTANT: 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 unbalanced blade will cause excessive vibration when rotating at
high speeds and may cause damage to the unit. The blade can be
tested by balancing it on a screwdriver or nail. Remove metal from the
heavy side until it is balanced evenly.
17
A
Figure 16