Hitachi PDA-100M - Page 6

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Durable motor
The motor of the Model PDA-100M is so designed that commutation sparks are minimized during operation in
order to increase the service life of the brush and the commutator. Table 1 shows the wear ratios of the brush
and the commutator as a result of continuous operation under the same loading conditions as general grinding
operation with respect to the current Model PDA-100D. The service life of the Model PDA-100M is about 1.5
times longer than the current Model PDA-100D and the running cost can be reduced.
Hitachi original dust proof construction for long service life against abrasion from dust
The Model PDA-100M is equipped with a motor whose durability is greater than the conventional models by
making the following improvements. The service life of the armature coil is 4 times longer than the
conventional models as a result of the gravel suction test (gravel is forcedly sucked in through the vents of the
tail cover).
The wedges at both ends of the armature coil are extended by 3 to 4.5 mm to protect the portions where the
peripheral speed is the fastest and apt to be disconnected by dust or gravel.
The protect tape covers the coil end at the fan side in order to protect the coil from being worn due to
collision with dust or gravel entered through the air vent and repelled by the fan.
The adhesive coating on the commutator hook prevents a break in the coil due to collision of dust or gravel
with the hook and a short circuit due to deformation of the hook.
Table 1
PDA-100D
1.0
1.0
Maker
Model
Carbon life ratio
Commutator life ratio
HITACHI
PDA-100M
1.4
1.5
0.9
1.1
1.0
1.0
B
C
Table 2
PDA-100D
1.0
Maker
Model
Durability ratio
HITACHI
PDA-100M
4.0
0.8
1.0
B
C
3 mm to 4.5 mm
3 mm to 4.5 mm