Craftsman 247.28933 Manual Del Operador página 26

BLaDEs
WaRning
Be sure to shut the engine off, remove ignition key, disconnect the
spark plug wire(s) to prevent unintended starting before removing the
cutting blade(s) for sharpening or replacement. Protect your hands
by using heavy gloves or a rag to grasp the cutting blade.
The blades may be removed as follows:
1. Remove the deck from beneath the tractor, (refer to Cutting Deck
Removal) then gently flip the deck over to expose its underside.
NOTE: Place a block of wood between the deck housing and the
cutting edge of the blade to help in breaking loose the hex nut securing
the blade.
2. Use a 15/16" wrench to loosen the hex flange nut securing the
blade to the bottom of the spindle assembly. Secure the spindle
by either holding the blade tightly, or by using a second wrench to
hold the nut at the top of the spindle.
3. Continue holding the blade onto the star hub of the spindle, and
remove the flange nut and cutting blade.
4. Repeat the previous steps to remove the other blade.
5. To properly sharpen the cutting blades, remove equal amounts
of metal from both ends of the blades along the cutting edges,
parallel to the trailing edge, at a 25° to 30° angle.
IMPORTANT: If the cutting edge of the blade has already been
sharpened to within 1-5/8" width from the opposite edge, or if any
metal separation is present, replace the blades with new ones. See
Figure 20.
Worn Blade
Edge
Sharpen Edge
Evenly
1-5/8 inch
SERVICE ANd MAINTENANCE
Blade Separation
Wind Wing
Figure 20
6. It is important that each cutting blade edge be ground equally to
maintain proper blade balance.
7. A poorly balanced blade will cause excessive vibration and may
cause damage to the tractor and result in personal injury. The
blade can be tested by balancing it on a round shaft screwdriver.
Grind metal from the heavy side until it balances evenly.
IMPORTANT: When replacing the blades, make certain the side of the
blade marked ''Bottom'' faces the ground when the mower is turned to
the operating position.
IMPORTANT: Note that the stars of the blades (and spindles) are not
symmetrical. The blade can be installed on each spindle in only one
direction. Carefully align the star hole of the blade with the star of the
spindle shaft when installing each blade. DO NOT improperly align the
blade and spindle shaft, and attempt to seat the blade onto the spindle
by tightening the hex flange nut.
8. Rotate the blade as necessary to align its star hole with the star
of the spindle shaft, then slide the blade onto the spindle shaft.
Thread the hex flange onto the spindle shaft and use a torque
wrench to tighten the hex flange nut to 70 to 90 foot-pounds.
9. Repeat the above procedure to install the other blade.
Checking Blade Timing
During normal operation the timing of the cutting blades can be altered
by abnormal loads on one, or both, cutting blades. Regularly check the
timing arrows on the spindle assemblies to make certain they are 90°
from each other.
If the timing arrows are not 90° from each other, proceed as follows:
1. Remove the deck from the tractor. Remove the idler bracket
backstop. Refer to Figure 21.
Bracket
Backstop
26
Spring & Screw
Idler Bracket &
Idler Pulley
Figure 21