Kubota Z400-B Handbuch Seite 219

Commutator
1. Rotate the armature in V blocks to check out-of-round ­
ness and run-out, setting a dial indicator with its tip on
the commutator.
2. If the variance among the readings is more than the
allowable limit, turn the armature in the lathe.
3. If the depth of undercut is less than the allowable limit,
undercut with a hacksaw blade or an undercutter.
4. Sand off all burrs with sandpaper .
• NOTE:
• When the smallest radius of the commutator is less than
the allowable limit, replace the armature shaft.
Variance on Allowable 0.05 mm
commutator
0.0.
limit 0.0020 in.
Commutator Allowable 31 mm
0.0. limit
1.22 in.
Commutator Allowable 0.2mm
undercut limit 0.008 in.
Field Coil
1. Check the continuity between the brushes.
2. If not continuous, replace the yoke assembly.
3. Check the continuity across the yoke and the brush or the
connecting lead.
4. If continuous, check for the breakage of the insulation.
5. If not repairable, replace the yoke assembly.
6. Check that the pole and windings are not loose.
Brush
1. Clean off the brush and check for the wear.
2. If unevenly worn, correct.
3. If worn to less than the allowable limit, replace.
4. Check that the brushes move freely in the brush holder.
I
Factory
17mm
specification 0.67 in.
I
Brush length
Allowable
11.5 mm
I
limit 0.453 in.
S·137