55
8. PERIODIC MAINTENANCE [Belt]
8.12 Inspection of Belt
When the belt tension is lowered, it slips and pro-
duce noise or larger vibration of the belt during
operation. Periodic check on the belt is needed.
Item
Load P
Bending
δ
Tension
Be sure to stop the unit and turn the power
OFF before inspecting the belt. Keep your
hand or other things away from the unit
while operation, or such action will cause
serious injury to the personnel.
WARNING
8.12.1 Visual Check of Belt and V-Pulley
q
Throw the light on the belt while moving and
check if there is any missing of rib or crack on it.
Likewise, check if there is any abnormal wear
or damage to the working surface of the V-pul-
ley and M-sheave.
w
Check if no slipping noise (squeaking noise or
creaking noise) is produced by the belt at
starting or while operation.
8.11.2 Measurement of Belt Tension
q
Prepare a flat plate (with length of about 600 mm).
w
Press the plate towards belt span surface of V-
pulley and M-sheave, then using a tension
meter to measure the pressing load and bend-
ing displacement at its span center.
If the bending is kept within the range shown
in the left table, there is no need for tension
adjustment. If deviation from the stated val-
ues is obvious, tension adjustment is needed.
Ask your dealer or Hitachi service station for
the adjustment.
e
It is possible to use a special tension meter to
measure tension of the belt directly. Ask your
dealer or Hitachi service station for more de-
tail of this measurement.
Do not adjust the belt tension too tightly.
Failure to observe this instruction may re-
duce the service life of the belts and/or
cause an unexpected accident.
CAUTION
0.69
0.84
0.92
0.69
0.84
0.92
58.8 to 98.1
883 to 1471
(6 to 10)
(90 to 150)
49 to 78.4
735 to 1177
(5 to 8)
(75 to 120)
Unit
Model
OSP-22
SA(R)
I
MA(R)
I
OSP-37
SA(R)
I
MA(R)
I
6.8
6.6
6.4
6.9
6.9
6.8
N
(kgf)
mm
MPa
N
(kgf)
Discharge
pressure
V-Pulley
Belt
Belt
Cover
M-sheave
A Flat Plate
(with length of
about 600 mm)
Tension
meter
Load P
Bending
δ
(mm)
Front Side