Hitachi DH 45SA, Технические данные и руководство по обслуживанию

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8-3. Structure of the DH 45SA Hammer Drill
Cylinder
Key
Striker
Air chamber
Bevel
gear Piston
Connecting rod
Crank shaft
First gear
Second hammer
Spline connection
O-ring
Second gear
Bevel pinion
Armature
Fig. 5
Rotation transmission
Rotation transmission is described with reference to Fig. 5. The gear arrangement of the DH 45SA has the
armature shaft positioned between the crank shaft and the bevel pinion shaft. Rotation of the armature shaft is
transmitted to the second gear through the first gear of the crank shaft and the second pinion. Then the
rotation is transmitted from the second gear through the slip mechanism disposed between the second gear
and the bevel pinion shaft to turn the bevel gear. The latter is keyed to the cylinder to rotate together. Cylinder
rotation is transmitted through the spline connection to the second hammer. Rotation is then transmitted to the
drill bit which is fitted into the hexagonal hole of the second hammer.
Hammering action
Armature rotation is transmitted to the crank and the connecting rod to reciprocally move the piston within the
cylinder. Air pressure developed between the piston and the striker changes as the piston moves. This causes
the striker to continuously hit the end face of the second hammer. Since the striker is moved under air
pressure, a certain air cushioning effect absorbs the striking shock.
If there is any leakage from the air chamber, the air cushioning effect becomes insufficient, resulting in an
incomplete shock absorbing effect. This is why the O-rings (attached to the striker and piston) for air tightness
are so important.
Second pinion