MacDon 742 HAY CONDITIONER - Manual (Page 68)

Form # 46290 Issue 09/05 66
MAINTENANCE/SERVICE
SICKLE AND SICKLE DRIVE (continued)
Changing Double Sickle Speed
Sickle drive is factory assembled for sickle speed
of:
12', 15' & 18': 1875 strokes per minute (spm)
21', 25', 30' & 36': 1695 spm
By exchanging pulleys (A) and (B) sickle speed
can be changed to:
12', 15' & 18': 1450 spm
21', 25', 30' & 36': 1310 spm
NOTE: Speeds listed are for windrower
applications. Sickle speed in combine applications
varies depending on combine.
To change sickle speed:
1. Loosen and remove cross-shaft drive belt (G).
See "Tightening Double Sickle Drive Belts",
below.
2. Remove three bolts (C) and separate pulley (B)
from the timing belt pulley.
3. Remove three bolts (D) and separate pulley (A)
from drive hub.
4. Exchange positions of pulleys (A) and (B) and
reassemble.
5. Tighten cross-shaft drive belt (G) and L/H
timing belt (L).
Double Sickle Drive Belt Tension
Check sickle drive belt tension after a 5 hour run-
in period and every 100 hours thereafter.
1. To tighten cross-shaft drive belt (G):
NOTE: If timing belt also requires tightening,
go to step 2.
a) Loosen two nuts (J) at driver pulley mounting
plate.
b) From outside of end sheet, turn adjusting bolt
(K) clockwise until a force of 12 lbs. (55 N)
deflects belt (G) 1/8 inch (3 mm) at mid-span.
c) Tighten nuts (J) to lock the position.
2. To tighten timing belts (L):
a) Loosen idler bolt (M)
b) Move idler pulley up until a force of 6 lbs. (28 N)
deflects timing belt (L) 1/2 inch (13 mm) at
middle of top span.
c) Tighten idler bolt (M).
d) Repeat at other side.
K
J
G
J
SICKLE DRIVE BELTS
TENSION ADJUSTMENT
M
L
CHANGING SICKLE SPEED
D
L B
G A
C