--- 10 ---
(6) Securely tighten the sleeve of the keyless chuck.
The keyless chuck may slip during operation if the shape of the drill bit shank is cylindrical depending on the
surface conditions, materials, etc. Please instruct the customers to retighten the keyless chuck more securely
if the keyless chuck slips during operation. The holding force of the keyless chuck is increased as the
tightening force of the keyless chuck is increased.
(7) Avoid continuous use.
Although the Model DS 7DF can bear continuous operation under certain conditions, operating conditions are
different depending on material of workpiece and sharpness of the drill bit in use. Please instruct the
customers to avoid continuous use of the Model DS 7DF and take a pause about 15 minutes after a single
charge operation as a guide.
B. Suggestions and precautions for the efficient use of the charger and storage batteries
If the Type FEB 7S or EB 712S storage batteries are exposed to direct sunlight for an extended period or if the
tool has just been operated for a long time, charging may not be possible if the temperature of a battery (type
FEB 7S or EB 712S) is above 40 ˚C (104 ˚F). In such a case, the customer should be advised to place the
battery in a shaded area with a good airflow, and allow sufficient cooling before recharging. This phenomenon is
common to all existing batteries and chargers which employ temperature sensitive overcharge protection devices.
The cooling time required before recharging can be accomplished varies from a few minutes to about 30 minutes,
depending on the load, duration of use, and ambient temperature.
Fig. 2
Schematic diagram of the feedback system
9. REFERENCE MATERIALS
9-1. Feedback System
The Model DS 7DF has the variable speed switch equipped
with the feedback system. This feedback system ensures a
sufficiently large torque even in the variable speed range
(Fig. 2). For example, when operating the Model DS 7DF at
a speed about 80% of the full speed, the maximum torque is
about 95% of that at a full speed (curve "A"). Even when the
Model DS 7DF is operated at a speed about 30% of the full
speed, the maximum torque does not decrease under about
65% of that at a full speed (curve "B") to ensure a sufficiently
large torque at a low speed.
Besides, the braking function allows the driver unit to stop
rotation immediately when the trigger switch is released,
Torque (%)
Full speed
Without feedback
system
Speed (%)
which is a convenient feature for continuous screw tightening or drilling works. The step-less variable speed
mechanism controls the speed depending on the depressed amount of the trigger switch within the range from 0
to 600 cycles per minute. Thanks to this mechanism, positioning is easily done for screw tightening and drilling
works.