Komatsu PC01 – HYDRAULIC EXCAVATOR – Flywheel, ignition coil, starter motor

a. Disassembly/reassembly
Starter motor equipped type:
Measure starter performance while cranking the engine.
If performance is not within service limits, disassemble and inspect as described on pages 8-3.

– Starter motor

b. Adjustment
– Ignition coil air gap
Adjustment is required only when the ignition coil or the flywheel has been removed.
1) Loosen the ignition coil bolts.
2) Insert a long thickness gauge or a piece of paper of the proper thickness between the ignition coil and the flywheel. Both gaps should be adjusted simultaneously.
3) Push the ignition coil firmly toward the flywheel and tighten the bolts.

c. Inspection
– Ignition Coil
<Primary side>
Measure the resistance of the primary coil by attaching one ohmmeter lead to the ignition coil’s primary (black) lead while touching the other test lead to the iron core.

<Secondary side>
Measure the resistance of the secondary side of the coil by removing the spark plug cap and touching one test lead to the spark plug lead wire while touching the other lead to the coil’s iron core.

– Spark plug cap
Measure the resistance of the spark plug cap by touching one test lead at the wire end of the cap, and the other at the spark plug end.

Replace the spark plug cap if the resistance is not within the range specified.

– Lamp coil
Measure the resistance between the wire terminals.

– Charge coil
(Model with electric starter)
Measure the resistance between the wire terminal and ground.

– Starter solenoid
Connect a 12 V battery between the starter terminal and the solenoid body and check for continuity between the terminals. Continuity should exist when the battery is connected and not exist when the battery is disconnected.

– Brush length
Measure the brush length.
If brush length is less than service limit, replace the brush and brush holder plate.

– Armature
– Continuity check-commutator segments
Check for continuity between the segments. If an open circuit (no continuity) exists between any two segments, replace the armature.

– Continuity check-commutator-to-shaft
Check continuity between the commutator and the armature shaft. Replace the armature if continuity exists between any of the commutator segments and the armature shaft.

– Mica depth
When the mica is clogged, or its depth is smaller than the service limit value, recut the grooves using a hacksaw blade or a small file.

– Continuity check-brushes
Remove the armature and check for continuity between the brushes.
There should be no continuity. (One of the brush holders is insulated.)

– Overrunning clutch
1) Check the overrunning clutch for smooth axial movement. Apply oil or replace the overrunning clutch if necessary.

2) Check the reduction gear movement by holding the pinion gear and turning the reduction gear. The reduction gear should turn counterclockwise freely and should not turn clockwise.

3) Check the pinion gear for wear or damage and replace if necessary.


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