MacDon 9250 SP - Manual (Page 96)

Form # 46584 Issue 11/06 Web Rev_01 94
MAINTENANCE/SERVICE
Header Drive
HEADER DRIVE BELT:
PULLEY FORE-AFT ALIGNMENT
Fore-aft misalignment of pulleys can cause a belt
failure where the backing band splits between V-
belt sections, as shown at (A).
Check and correct the pulley fore-aft alignment in
the following order:
1. Rear pulley must be square to frame as shown.
To check, place a straight edge along side of
rear pulley and check that clearance to frame at
(L) and (M) is equal. To adjust, loosen nut (N)
and move R/H gearbox mount forward or back
to square rear pulley. Tighten nut (N) to secure
the position.
NOTE: Dimension at (L) and (M) should be
approximately 17 mm (0.67"), but never less
than 13 mm (0.51") to allow for removal and
installation of drive belt.
2. Rear pulley must align with front pulley as shown below. To check, place a straight edge along side of rear
pulley and check that dimension (C) at front pulley is 6 mm (0.24"). To adjust, loosen taper lock bushing (T)
at rear pulley and move pulley on gearbox shaft. Ensure that pulley hub or bushing does not contact
gearbox seal. Tighten bushing (T) to secure the position.
NOTES: · If (C) is different than (D), see step 4.
· If 6 mm dimension can not be achieved by moving bushing (T), go back to step 1 and purposely misalign
rear pulley with frame to obtain 6 mm dimension at (C). Then proceed with steps 3 and 4.
3. Flat idlers must align with each other as shown. Dimension (F) must equal dimension (G) within 2 mm
(0.08"). To adjust idlers, bend mounting arms to suit. (It may be necessary to heat idler arms to permit
adequate bending.)
4. Front pulley must be square to rear pulley as shown. To check, place a straight edge along side of front
pulley and check that dimension (E) is 6 mm (0.24"). To adjust, shim front pulley mounting plate at both
front bolts, or both rear bolts so that dimensions (C), (D) and (E) are all 6 mm (0.24").
BELT FAILURE DUE TO FORE-AFT MISALIGNMENT
REAR PULLEY SQUARE TO FRAME
REAR PULLEY ALIGNED WITH FRONT PULLEY AND IDLERS ALIGNED
FRONT PULLEY SQUARE TO REAR PULLEY