Hitachi FDV 20VB Technical Data And Service Manual page 10

(3) Direction of rotation
The underside of the housing is labeled with "R" and "L". Viewed from the handle, the drill chuck rotates
clockwise (right) with the switch-top lever set to "R" and counterclockwise (left) with the lever set to "L". Be
sure the motor is brought to a complete stop before shifting the lever between "R" and "L".
Counterclockwise
(4) Speed control switch
The FDV 20VB switch allows adjustment of the motor rotation within a range of about 25% to 60% of the full
rotation speed by changing the trigger stroke.
The SCR incorporated in the switch for phase control of the power supply causes heat release to rise with
increasing current.
When the switch is used at S
gradually raise the heat release from the SCR eventually to a level high enough to break the SCR. To avoid
this, release the switch immediately, whenever the motor becomes jammed.
Trigger stroke (0-S )
2
Be sure to wait until the motor stops completely before performing the above changeovers from (1) to (3).
(5) Be sure to set the switch lever to "R" for grinding operations, for instance with the drill chuck holding the
sanding set or the mounted wheel.
- S in the figure below, keeping the switch energized with the motor locked will
0 1
Label
Clockwise
Lever
100 %
Stopper
60 %
25 %
0
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Trigger stroke