Isuzu N-Series. Manual - part 630

ENGINE ELECTRICAL 6D-13

9. Return Spring

Remove the return spring from magnetic switch.

10. Steel Ball

Remove the steel ball from the overrunning clutch.

11. Idle Pinion

Remove the idle pinion from housing.

12. Retainer

Remove the retainer from housing.

N6A3498E

N6A3499E

N6A3500E

N6A3501E

6D-14 ENGINE ELECTRICAL

13. Roller
14. Magnetic Switch

Inspection and Repair

Make necessary correction or parts replacement if wear,
damage or any other abnormal condition are found
through inspection.
Armature
Check the commutator for run-out and replace if the
amount of run-out exceeds the limit.

Check the mica segment for wear.

Check the commutator outer diameter.

Run-out test

mm (in)

kw

Standard

Limit

2.2

0.02 (0.0008)

0.05 (0.0020)

2.0

N6A3502E

N6A3503E

Depth of mica segment

mm (in)

kw

Standard

Limit

2.2

0.7 — 0.9 (0.028 — 0.035)

0.20 (0.008)

2.0

Legend

1. Insulator
2. Commutator segments

Commutator outer diameter

mm (in)

kw

Standard

Limit

2.2

35.00 (1.378)

34.00 (1.339)

2.0

N6A3504E

N6A3505E

ENGINE ELECTRICAL 6D-15

Armature Short Circuit Test
Check the armature for short circuit by placing it on a
growler tester. Hold a piece of hacksaw blade against
the armature core while slowly rotating the armature. A
short-circuited armature will cause the blade to vibrate
and to be attracted by the core. If the hacksaw blade is
attracted or vibrates, the armature, is short circuited,
and must be replaced.

Armature Ground Test
Touch one probe of a circuit tester to the commutator
segment and the other to the armature core. There
should be no continuity. If there is a continuity, the arma-
ture is grounded. Replace the armature if it is grounded.

Armature Continuity Test
Connect the probes of a circuit tester across the 2 seg-
ments. There should be continuity at any test points.
Replace if it is open-circuited.

Yoke
Field Winding Ground Test
Using circuit tester, touch one probe to the field winding
end or brush and the other to the bare surface of yoke
body.
There should be no continuity. If the tester indicates a
continuity, the field coil is grounded and yoke assembly
should be replaced.

Field Winding Continuity Test
Using a circuit tester, touch one probe to the “C” terminal
lead wire and the other to the brush. There should be
continuity. Replace the yoke if it is open.

N6A3506E

N6A3507E

N6A3508E

N6A3509E

6D-16 ENGINE ELECTRICAL

Brush and Brush Holder
Measure the brush length and replace if it is worn be-
yond the service limit.

Brush Holder Insulation Test
Using a circuit tester, check the brush holder insulation.
Touch one probe to the holder plate and the other to the
positive brush holder. There should be no continuity.

Overrunning Clutch
Inspect the teeth of pinion for wear and damage.
Replace if it damaged.
Rotate the pinion in direction of rotation (clockwise).
It should rotate smoothly. But in opposite direction, it
should be locked.

Bearing
Check the bearings for wear and damage. If the bear-
ings are noisy during operation, they should be re-
placed.

Brush length

mm (in)

kw

Standard

Limit

2.2

14.5 (0.57)

10 (0.39)

2.0

16 (0.63)

N6A3510E

N6A3511E

N6A3512E

N6A3513E