General; Sharpening - Jacobsen HR5111 Service And Repair Instructions

GENERAL

Every 50 hours examine the cutter bars to make sure
they are in good operating condition. See Figure 12E-1.
1. The blades should follow along a straight line and
should not be bent.
Replace all bent blades. The damage may include
a microscopic crack which could grow, allowing a
piece of the bar to break off and be thrown out
from under the mower, causing serious bodily injury.
2. Examining the ends of the blades and at the bend
of the air vanes, inspect edge of bar to determine
if bar is becoming thin.
WARNING
Do not attempt to bend blade back to its original
flat condition. Replace bar.
3. If wear is allowed to continue, a slit will develop
and grow, permitting a piece of the blade to break
off. At the first sign of a slit in the bar, the bar must
be replaced.

SHARPENING

When dressing or resharpening the blades, DO NOT
follow the original angle of grind "A", Figure 12E-2.
1. Grind new cutting edges on a diagonal as shown
in "B".
2. Do not exceed 1/2" (12.7 mm) total metal removed
at end of bar.
3. Make sure that each cutting edge receives an equal
amount of grinding to prevent having an unbal-
anced bar, which will cause excessive vibration at
high speeds and may damage the mower.
DANGER
Incorrect resharpening of the blade beyond the
point illustrated in "B", Figure 12E-2, may result
in a broken blade tip which may be discharged
from under the mower.
4. After blade has been sharpened it must be bal-
anced (see Figure 12E-3).
5. If blade is out of balance remove metal on the
heavy end by grinding until bar is balanced.
SECTION 12E. BLADES
12E-1
ATTACHMENTS
Figure 12E-1. Condition of Blades
Figure 12E-2. Sharpening
Figure 12E-3. Blade Balance
12E