Hitachi WH 12DM2 Technical Data And Service Manual page 13

(8) Low operating noise (-1 dB with respect to the previous model)
The operating noise of the Models WH 12DM2/WR 12DM2 is low and dull thanks to the large hammer and the
optimized impact timing. Thus the large hammer tightens screws powerfully with lower operating noise than
the Model WH 12DM. (Refer to page 26 for details.)
(9) Enhanced maintainability
The carbon brushes are replaceable and the armature is singly replaceable thanks to the separate-type motor
like a 100-V motor (the previous model has the same construction).
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