Makita 6906 - Manual (Page 6)

6
Operation
The proper tightening torque may differ depending upon the kind or size of the bolt. The relation between tight-
ening torque and tightening time is shown in the figure below.
kg•cm
Hold the tool firmly and place the socket over the bolt or nut. Turn the tool on and tighten for the proper tighten-
ing time.
NOTE:
• Hold the tool pointed straight at the bolt or nut without applying excessive pressure on the tool.
• Excessive tightening torque may damage the bolt or nut.
The tightening torque is affected by a wide variety of
factors including the following. After tightening,
always check the torque with a torque wrench.
1. Socket
• Failure to use the correct size socket will cause
a reduction in the tightening torque.
• A worn socket (wear on the hex end or square
end) will cause a reduction in the tightening
torque.
2. Bolt
• Even though the torque coefficient and the
class of bolt are the same, the proper tighten-
ing torque will differ according to the diameter
of bolt.
• Even though the diameters of bolts are the
same, the proper tightening torque will differ
according to the torque coefficient, the class of
bolt and the bolt length.
3. The use of the universal joint or the extension
bar somewhat reduces the tightening force of the
impact wrench. Compensate by tightening for a
longer period of time.
4. The manner of holding the tool will affect the
torque.
MAINTENANCE
CAUTION:
Always be sure that the tool is switched off and
unplugged before carrying out any work on the tool.
Replacement of carbon brushes (Fig. 4 & 5)
Replace carbon brushes when they are worn down to
the limit mark. Both identical carbon brushes should
be replaced at the same time.
To maintain product safety and reliability, repairs,
maintenance or adjustment should be carried out by
a Makita Authorized Service Center.
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0 1 2 3 4 5 6 7 8
For 6906
For 6905B
Tightennig time
Rated voltage
90% of rated voltage
T
igh
ten
ing
tor
qu
e
seconds