Reference Materials; Lubrication; Tool Structure - Hitachi DH 14DL Technical Data And Service Manual

14.4/18 v cordless rotary hammer

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Handling instructions manual (108 pages)

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Table Of Contents

Table of Contents

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.

Fig. 1

Rod

Piston pin

Slide plate

Motor shaft

First gear

Slide plate

Reciprocating bearing

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.