MacDon CA25 OM - Manual (Page 139)

SECTION 8. MAINTENANCE AND SERVICING
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137
Revision B
8.9.9 Double Knife Drive Belts: Timed
Drive
This section applies to 35 ft. and smaller
Double Knife headers with timed drives. For
Single Knife headers and non-timed Double
Knife headers, refer to Section 8.9.8 Sickle
Drive Belts: Non-Timed Drive.
8.9.9.1 Left End Drive
Remove endshield at left end of header. Refer
to Section 7.2.3 Endshields.
CAUTION
To avoid personal injury, before servicing
machine or opening drive covers, follow
procedures in Section 8.1 PREPARATION
FOR SERVICING.
Tension Adjustment: Timing Belt
IMPORTANT
To prolong belt and drive life, do
NOT over-tighten belt.
a. Loosen two nuts (A) on sickle drive belt idler
bracket.
b. Insert a long punch (or equivalent) into hole (B)
in idler bracket, and pry downward until a force
of 6 lbf (27 N) deflects timing belt 1/2 in.
(13 mm) at mid-span (C).
c. Tighten nuts (A) on idler mounting bracket.
d. Check clearance between belt and belt guide
(D). The measurement should be
0.02–0.04 in. (0.5 -1.0 mm). Adjust as follows:
1. Ensure belt is properly tensioned.
2. Loosen bolts (E), and adjust position of
guide as required.
3. Tighten bolts.
e. Re-adjust tension of a new belt after a short
run-in period (about 5 hours).
Removal: Left End Timing Belt
a. Loosen two nuts (A) on belt idler bracket to
relieve tension on belt.
b. Loosen nut (F) on idler pulley, and slide idler
down to loosen belt.
c. Loosen two bolts (G) on endsheet.
(continued next page)
B
A
C
A
F
G
0.02 - 0.04 in.
(0.5 - 1.0 mm) GAP
E
D