Hitachi DH 30PC2 Technical Data And Service Manual page 18

Slip clutch mechanism
A clutch plate holding a steel ball is inserted between the second gear and the spring as a slip mechanism in
the Model DH 30PC2. If an excessively large torque is applied to the tool shaft, the second gear idles and
does not transmit rotation.
The slip torque is adjusted by the slip plate and the belleville (coned disk) spring pressure. With the
arrangement, the clutch slips when an excessive torque is applied to the working tool as when the drill bit
contacts steel bar/wire in the concrete, protecting the operator from unexpected motion of the side handle.
Sealing and dust-proof structure
The cylinder case and crank case section is tightly sealed with O-rings and oil seals as shown in Fig. 5. This
prevents leakage of grease from the cases, while also protecting them against dust from outside. The drill bit
chuck portion is protected by a rubber front cap to keep out dust and chips which could cause improper fitting
of the drill bit and/or other faulty operation of the chuck portion. The speed control switch is also a fully dust-
proofed type to prevent dust and chips from entering the handle section and causing possible operational
trouble or a break down of the insulation.
Front cap O-ring O-ring
O-ring
Oil seal
Oil seal
Oil seal
Fig. 5
Speed control
The Model DH 30PC2 is equipped with a variable speed control switch which permits free change of the
rotation speed and hammering force. When drilling in fragile materials, pull the switch trigger gently for low
rotation speed (hammering force) to achieve optimum results.
Handle and side handle
The handle section is of a two-layer structure. The base is made of glassfiber-reinforced plastic and the
outside layer is soft resin. They are molded in one piece.
The side handle also has a two-layer structure. The base is made of glassfiber-reinforced plastic base with a
steel nut and the outside layer is soft resin. They are molded in one piece. The newly designed handle and
side handle structure ensures more comfortable grip for improved operability.
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