SECTION 58 - DRIVELINES - CHAPTER 3
58-9
If a cutter bar failure is experienced, check the cutter
bar components in the following sequence:
A. Inspect the external components for damage,
paying particular attention to the knives and
discs. Broken knives and bent or cracked discs
are a result of contact with solid foreign objects,
and may indicate possible internal damage. A
disc out of time may also indicate internal
damage; the discs are properly timed when they
are positioned 90° to each other.
Misalignment or gaps between the disc modules
and spacers may indicate the tie bolts are loose or
broken, or the dowel pins between the
components have failed or are missing.
B. Carefully grab both ends of each disc, and try
to “rock” the disc back & forth. A small amount
of movement (0.060 in) is normal; an excessive
amount of movement may be the result of a loose
disc hub retaining bolt, or could indicate a worn
top cap housing or bearings. Disc modules with
excessive disc “rock” should have the disc
retaining bolts and disc hub bolt checked for
proper torque. If the bolts are tight, and
movement still exists, the top cap assembly may
need to be replaced.
C. Starting at the left end of the cutter bar, grab
both the #1 and #2 discs, and slowly rotate
both discs while applying pressure to one of
the discs against the direction of rotation. If
one disc suddenly moves, it may indicate damage
to the gear teeth in that module. Excessive free
play between discs, or if one disc may be turned
freely without the other disc moving, may indicate
excessive wear or failure of the intermodule shaft.
Some rotational free play (3/16 in) between
adjacent discs is normal, as a result of the
backlash in both gear sets.
Check all disc modules by working gradually
across the cutter bar, checking each disc to the
next disc. In some cases, two adjacent modules
may sustain damage from the same event, or
there may be two separate failures on the cutter
bar, involving modules in different locations.
It is also necessary to check the bevel gearbox
and drive module components for damage. To do
this, remove the outer belt shield, and hold the
driven sheave while slowly rotating the #1 disc to
check these components.
D. After checking all disc modules for evidence
of internal failure, remove the discs and top
cap assemblies of any module with suspected
damage. Inspect both the top cap assembly and
the lower module assembly for bearing play or
damage, and gear tooth damage. Grab the pinion
shaft, and rotate the adjacent discs to check for
play in the intermodule shaft splines. If only the
top cap assembly components are damaged, it is
not necessary to disassemble the cutter bar
further. Before installing the replacement top cap
assembly, drain the oil, flush the lower module
with a cleaning solvent to remove contaminants
and install fresh Case Akcela 135 H EP 80W90
gear oil.
E. The cutter bar should only be disassembled if
it has been determined that the lower module
components or the intermodule shafts are
damaged. Ensure that all disc modules were
checked as per steps B. C & D to determine which
modules require removal for repair or
replacement. Check the intermodule shaft on
both sides of a failed disc module for worn or
twisted splines.
The cutter bar should also be disassembled if
misalignment or gaps between the modules and
spacers was noted in step A. Check the
intermodule shafts and pinions shafts for
excessive spline wear at any connection where
the tie bolts were found to be loose or failed, or
where misalignment occurred due to missing or
failed dowel pins. Note that dirt will tend to work its
way inside spacers where the tie bolts are loose.
NOTICE: Following all of the above listed steps when
inspecting a failed cutter bar should ensure all
components are checked, and any worn or failed
components are identified prior to disassembly and
repair of the cutter bar.
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