14
1. Lubrication
Replenish the grease lubricant when the tool is disassembled or there is grease leakage due to a defective
seal. Changing grease is required once a year to extend the service life of the tool. Special grease is used
in the striking section. Should the striking section (within the gear cover) be disassembled, remove the old
grease from all parts completely and, on reassembly, replenish 30 g of new grease in the gear cover and
10 g in the groove of the inner cover. Be careful not to exceed the designated amount of grease. Excessive
grease will reduce striking efficiency.
2. Tool structure
Transmission of rotation
See Fig. 1. The rotation of the armature is transmitted to the second shaft via the first gear, and causes
it to rotate. The second shaft pinion mounted on the second shaft engages the second gear mounted on
the outer circumference of the cylinder. The cylinder is coupled to the second gear by means of a slip
mechanism, and they rotate together. The end of the cylinder also functions as the drill bit retainer. The
cylinder is key-connected to the inserted drill bit by means of two key rails and a steel ball, and transmits
rotation to the drill bit.
Piston reciprocating mechanism
In the Models DH 14DL, DH 14DMR, DH 18DL and DH 18DMR, through adoption of a spiral drive
system (a mechanism using a reciprocating bearing), a more compact design has been achieved by
arranging the motor shaft in parallel with the tool shaft. Figure 1 shows that the drill bit is pressed
against the workpiece and the tool shaft is retracted. The rotation of the armature is transmitted to the
second shaft via the first gear. The second shaft rotation is further transmitted through a spline to the
clutch. The cylinder flange is pressed against the clutch by the retracted tool shaft and the clutch
engages with the reciprocating bearing to transmit rotation to the reciprocating bearing. However,
circular grooves on the inner race of the reciprocating bearing are positioned on an angle of inclination
with relation to the second shaft.
The rotation of the inner race and the shaft causes that angle of inclination to change regularly forward
and backward with relation to the second shaft, and produces a rocking motion to the outer race of the
reciprocating bearing. Finally, a rod extending from the outer race of the reciprocating bearing is
connected to the piston by the piston pin, and causes the reciprocating bearing motion of the piston.
REFERENCE MATERIALS
Rod
Air chamber
Striker
Slip mechanism
Steel ball
O-ring
Cylinder
Key rail (2 pcs.)
Tool shaft
Slide plate
Piston pin
Motor shaft
First gear
Slide plate
Reciprocating bearing
Second hammer
Second gear
Second pinion
Cylinder flange
Spline
Second shaft
Clutch
Piston
Fig. 1
