MacDon 742 HAY CONDITIONER - Manual (Page 69)

Form # 46290 Issue 09/05 67
SICKLE TIMING
DOUBLE SICKLE IDLER ALIGNMENT
MAINTENANCE/SERVICE
SICKLE AND SICKLE DRIVE (continued)
Double Sickle Drive Belt Tracking
To correct double sickle timing belts from riding hard
against either flange of idler pulley:
1. Use a 15/16 deep socket and pry bar on nut
securing idler pulley as shown.
2. If belt is riding against outside flange, push bar
forward to change pulley alignment.
3. If belt is riding against inside flange, push bar
rearward.
Sickle Timing (Double Sickle Headers)
To prevent excessive vibration, the left and right sickles
must be accurately timed to move in opposite directions.
Timing is achieved by rotating the wobble box pulley as
required when installing the wobble box drive belts.
CAUTION: Before timing sickles remove keys
from power unit. Be sure cutterbar is clear
before turning sickle drive.
To time the sickles:
1. Install the left hand wobble box drive belt and tension as
described (previous page). Check that the belt is properly
seated in the grooves on both driver and driven pulleys.
2. Rotate the left hand wobble box driven pulley clockwise
until the left hand sickle (A) is at the center of the inboard
stroke (moving towards the center of the header).
NOTE: Center stroke is when the sickle sections are
centered between the guard points as shown.
3. Remove the right hand drive belt from the
wobble box pulley and rotate the pulley counter
clockwise until the right hand sickle (B) is also
at the center of the inboard stroke.
IMPORTANT: It is critical that sickles are
centered at guard points while both are moving
towards the center of the header, not one
moving inboard and one moving outboard.
4. Install the right hand wobble box drive belt and
tension as described (previous page).
NOTE: To maintain timing, wobble box driver
and driven pulleys must not rotate as the belt is
tightened.
Tighten all hardware and check that the belt is
properly seated in the grooves on both driver and
driven pulleys.
5. Check for correct sickle timing by rotating the rear cross-shaft slowly. Observe sickles where they over-lap
at the center of the header.
IMPORTANT: At the start of each stroke, sickles must move in opposite directions and must begin to move
at exactly the same time. If timing is slightly off, loosen right hand belt just enough to allow skipping the belt
one or more teeth as required: If R/H sickle "leads" L/H, rotate right hand driven pulley clockwise. If R/H
sickle "lags" L/H, rotate pulley counter-clockwise. Tighten right hand belt.