Chuck Section; Dust Collector (B) - Hitachi DH 20PB Technical Data And Service Manual

8-6. Chuck Section

Fig. 6 shows the construction of the chuck section.
Forward
The opening where the drill bit is inserted is covered with a front cap (rubber) to prevent dust from entering inside.
When the drill bit is inserted, the steel ball fits into the matching groove on the drill bit to lock it in place and
prevent it from falling out . Two key rails transmit rotating torque to the drill bit. The drill bit can be released by
simply pulling the grip back. The grip is held forward by a holder spring. To mount a drill bit, pull the grip back to
compress the holder spring. The steel ball then moves outward. While turning the drill bit, push it until it makes
contact and is fully inserted. Then release the grip so that it moves forward and fixes the drill bit. To remove the
drill bit, simply pull the grip back fully and pull the drill bit out.

8-7. Dust Collector (B)

While drilling holes overhead, dust collector (B) can be mounted on the Model DH 24PE to prevent dust and chips
from falling downward. Dust collector (B) is intended solely for use when drilling holes in concrete, and cannot be
used for drilling holes in steel or wood. It is designed for use with drill bits with overall length of 166 mm, 160 mm
or 110 mm, and cannot be used with any longer bits. When using a drill bit with an overall length of 166 mm with
dust collector (B), drilling up to a depth of approximately 72 mm is possible. When using dust collector (B),
ensure it is securely fastened to the grip on the main body with socket adapter (B).
Although the socket and socket adapter (B) rotate together with the tool shank, there is a steel ball between the
outer race and the socket which serves as a ball bearing. Should the dust cover be forced against the concrete
surface, it will not rotate even though the tool shank continues to rotate. Should the tool be operated when the
dust cover is not being held against a concrete surface, inertia may cause dust collector (B) to become
disconnected from the grip. Accordingly, caution the customer to press dust collector (B) and drill bit firmly against
the concrete surface before turning on the switch to start drilling.
When dust collector (B) is used, almost no dust and chips are scattered about. However, since the chips and dust
remaining in the collector may scatter after completion of the drilling operation, the customer should be advised to
always wear protective glasses.
When dust collector (B) is disassembled for repair or maintenance, be very careful to prevent oil or grease from
adhering to the steel balls. Grease or oil on the steel balls may cause concrete dust to enter the unit and cause
defective rotation.
Steel ball
Front cap
Grip
Backward
Cylinder
Washer (B)
Holder spring
Key rails
(two pieces)
Ball holder
Fig. 6
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