SECTION 58 -- ATTACHMENTS AND HEADERS -- CHAPTER 2
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 dam-
age; 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 compo-
nents 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″) 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 retain-
ing 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 re-
placed.
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 dam-
age 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 intermo-
dule shaft. Some rotational free play (3/16″) be-
tween 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 sus-
pected damage. Inspect both the top cap as-
sembly and the lower module assembly for bear-
ing 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 re-
placement top cap assembly, drain the oil, flush
the lower module with a cleaning solvent to re-
move contaminants and install fresh API GL5
80W90 oil.
E. The cutter bar should only be disassembled
if it has been determined that the lower mod-
ule 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 re-
placement. 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 intermo-
dule shafts and pinions shafts for excessive
spline wear at any connection where the tie bolts
were found to be loose or failed, or where mis-
alignment occurred due to missing or failed dow-
el pins. Note that dirt will tend to work its way in-
side spacers where the tie bolts are loose.
NOTE: Following all of the above listed steps when
inspecting a failed cutter bar should ensure all com-
ponents are checked, and any worn or failed compo-
nents are identified prior to disassembly and repair of
the cutter bar.
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