Yanmar 4LHA-HTP Operation Manual page 639

Chapter 9 Electrical System
3. Starter Motor
6.2 Field coil
(1) Field coil continuity and ground test.
Field coil continuity test
Field coil insulation test
Check point
Kind of test
Terminal
Continuity
between field coil
Field coil
Insulation
between yoke
6.3 Brush
(1) Brush dimensions
Replace brushes which have been worn beyond the
specified wear limit.
Standard
height
USED
NEW
Brush standard height
Wear limit.
Normal Abnormal
YES NO (Wiring broken)
NO Y E S (Short-circuit)
Replace the brush if it is
wom up to the bottom of
the Hitachi trademark
(approximately one-half its
.original length)
Wear limit
mm (in.)
S13-41A
18(0.7087)
7(0.2756)
(2) Brush appearance and movement in brush holder
If the outside of the brush is damaged, replace it. If the
movement of the brushes in the brush holder is
hampered because the holder is rusted, repair or
replace the holder.
(3) Brush spring
Since the brush spring pushes the brush against the
commutator while the motor is running, a weak or
defective spring will cause excessive brush wear,
resulting in sparking between the brush and the
commutator during operation. Measure the spring
force with a spring balance; replace the spring when
the difference between the standard value and the
measured value exceeds ±0.3kg (0.66 Ib)
Spring balance
Brush spring
Standard spring load
(4) Brush holder ground test
Check for continuity between the insulated brush holder
and the base of the brush holder assembly. Continuity
indicates that these two (-
grounded and that the holder must be replaced.
9-13
, 4LHA Serii
Wear limit ± 2.9 (0.3) N(kgf)
(Measuring brush spring force)
S13-41A
31.4 (3.2) N(kgf)
between +) points are