MacDon D50 - Knife Drive; Knife Drive Belts; Untimed Knife Drive Belts

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4.8 Knife Drive
The knife drive system transforms pumped hydraulic pressure into a mechanical motion that strokes a series of serrated
knife blades at the front of the header back and forth to cut a variety of crops.
4.8.1 Knife Drive Belts
Untimed Knife Drive Belts
This section applies to single-knife headers and to 12.2 m (40 ft.) double-knife headers with untimed knife drives.
Tensioning Untimed Knife Drive Belts
The procedure for tensioning untimed knife drive belts is the same for single- and double-knife headers.
DANGER
To prevent bodily injury or death from the unexpected start-up or fall of a raised machine, always stop the engine and
remove the key before leaving the operator’s seat, and always engage the safety props before going under the
machine for any reason.
IMPORTANT:
To prolong belt and drive life, do NOT overtighten the belt.
1. Shut down the engine, and remove the key from the ignition.
2. Open the endshield. For instructions, refer to 4.3.1 Opening Hinged Endshield, page 116.
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A
B
C
Figure 4.73: Untimed Knife Drive
3. Loosen two bolts (A) securing the motor assembly to the
header endsheet.
4. Turn adjuster bolt (B) clockwise to move the drive motor
until a force of 89 N (20 lbf) deflects belt (C) 20–25 mm
(3/4–1 in.) at the midspan.
5. Tighten bolts (A) and the jam nut on bolt (B).
MAINTENANCE AND SERVICING