Repair Guide; Precautions On Maintenance, Inspection And Repair; Inspection Criteria For Each Section And Consumable Parts - Hitachi CM 75EAP Service Manual

This section describes repair, focusing on portions requiring frequent repair. See the TROUBLESHOOTING
GUIDE in the previous section as the context for the following descriptions.

1. Precautions on maintenance, inspection and repair

• The fuel used readily ignites; therefore, never bring the product near a flame.
• Use new gaskets at reassembly.
• Prior to disassembly for repair, remove the fuel into separate containers, and allow the tool to cool down.
• During repair, startup or running, use adequate care for portions posing the risk of burn injury or electric
shock, such as hot areas including the muffler, high voltage cord, and spark plug.
• Before running the tool with the cut-off wheel attached, make sure that there are no other people nearby.
• Ensure proper ventilation when performing repair in a small room or other poorly ventilated space.

2. Inspection criteria for each section and consumable parts

Item
Idling revolutions
No-load maximum revolutions
(with cut-off wheel)
Clutch engagement
Spindle revolutions
Accelerating performance
Gap between magneto rotor
and ignition coil ass'y
Spark plug
Gap between spark plug
electrodes
Diamond cutter dimensions
Cut-off wheel dimensions
Max. circumferential speed of
cut-off wheel
* This engine cutter controls the maximum speed to 9,800 ± 400 min
from breaking. Therefore, the pulse-count type of tachometer used for detecting ignition plug firing pulses
cannot measure maximum speed. Use one of the following methods to measure maximum speed:
• Use a tachometer of the electromagnetic induction type for detecting the movement of magnetic steel in
the magneto rotor.
• Use a stroboscope or similar instrument to measure the cut-off wheel rotation (spindle speed). Make a
safety check before running the cut-off wheel, and be very careful to avoid injury.

REPAIR GUIDE

Model
CM 75EAP
305 mm in outside dia.
20 mm in hole dia.
(A diamond cutter of 25.4 mm in hole dia. is available
305 mm in outside dia.
20 mm in hole dia.
3.5 mm in thickness
(A cut-off wheel of 25.4 mm in hole dia. is available
80 m/s
2,500 ± 200 min
9,800 ± 400 min
3,800 ± 300 min
4,050 ± 150 min
Smooth acceleration
0.2 to 0.4 mm
NGK BPMR7A
0.6 to 0.7 mm
when using the accessory adapter collar.)
when using the accessory adapter collar)
-1
in order to prevent the cut-off wheel
-3-
CM 75EBP
-1
-1
-1
-1
355 mm in outside dia.
20 mm in hole dia.
355 mm in outside dia.
20 mm in hole dia.
4.0 mm in thickness
100 m/s