12-20 DF9.9T/TH “K8” (’08) MODEL
Ensure that the mica (insulator) between commutator segments
is undercut to specified depth.
Commutator undercut:
Standard 1.6 – 1.9 mm (0.06 – 0.07 in)
Service limit 1.0 mm (0.04 in)
If undercut is less than service limit, cut to specified depth.
NOTE:
Remove all particles of mica and metal using compressed air.
Brushes
Check the length of each brush.
09900-20101: Vernier calipers
Brush length:
Standard 10.0 mm (0.39 in)
Service limit 5.0 mm (0.20 in)
If brushes are worn down to the service limit, they must be
replaced.
O-ring
Inspect the O-ring between the PT motor and PT pump case.
Replace if cuts, nicks or tears are found.
ASSEMBLY
Assembly is reverse of disassembly with special attention to fol-
lowing steps.
• Install armature to brush holder first.
When installing the armature, use care to avoid breaking the
brushes.
• Match up previously scribed alignment marks.
• Install the field case.
Wear safety glasses when using compressed air.
SEGMENT
MICA
Commutator undercut
O-ring
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