Operation; Maintenance - Makita BTW074 Instruction Manual

ASSEMBLY
CAUTION:
• Always be sure that the tool is switched off and the bat-
tery cartridge is removed before carrying out any work
on the tool.
Selecting correct socket
Always use the correct size socket for bolts and nuts. An
incorrect size socket will result in inaccurate and incon-
sistent fastening torque and/or damage to the bolt or nut.
Installing or removing socket
1. For socket without O-ring and pin (Fig. 7)
To install the socket, push it onto the anvil of the tool
until it locks into place.
To remove the socket, simply pull it off.
2. For socket with O-ring and pin (Fig. 8)
Move the O-ring out of the groove in the socket and
remove the pin from the socket. Fit the socket onto
the anvil of the tool so that the hole in the socket is
aligned with the hole in the anvil. Insert the pin
through the hole in the socket and anvil. Then return
the O-ring to the original position in the socket
groove to retain the pin. To remove the socket, fol-
low the installation procedures in reverse.

OPERATION

[*1] Presetting number of impacts is impossible for more
than 200 impacts (4 seconds).
[*2] Fastening time includes when you pull the trigger
completely.
CAUTION:
• Hold the tool firmly and place the socket over the bolt
or nut. Turn the tool on and fasten for the proper fas-
tening time and number of impacts (presetting num-
ber).
• If the tool is operated continuously until the battery car-
tridge has discharged, allow the tool to rest for 15 min-
utes before proceeding with a fresh battery.
The proper fastening torque may differ depending upon
the kind or size of the bolt, the material of the workpiece
to be fastened, etc. The relation between fastening
torque and fastening time is shown in the figures. (Fig. 9,
10, 11 & 12)
NOTE:
• When fastening bolt M8 or smaller, carefully adjust
pressure on the switch trigger so that the screw is not
damaged.
• Hold the tool pointed straight at the bolt or nut without
applying excessive pressure on the tool.
• Excessive fastening torque may damage the bolt/nut or
socket. Before starting your job, always perform a test
operation to determine the proper fastening time for
your bolt or nut. Especially for the bolt smaller than M8,
perform the above test operation to prevent the trouble
on socket or bolt, etc.
• If the tool is operated continuously until the battery car-
tridge has discharged, allow the tool to rest for 15 min-
utes before proceeding with a fresh battery cartridge.
The fastening torque is affected by a wide variety of fac-
tors including the following. After fastening, always check
the torque with a torque wrench.
1. When the battery cartridge is discharged almost
completely, voltage will drop and the fastening
torque will be reduced.
8
2. Socket
• Failure to use the correct size socket will cause a
reduction in the fastening torque.
• A worn socket (wear on the hex end or square
end) will cause a reduction in the fastening torque.
3. Bolt
• Even though the torque coefficient and the class of
bolt are the same, the proper fastening torque will
differ according to the diameter of bolt.
• Even though the diameters of bolts are the same,
the proper fastening torque will differ according to
the torque coefficient, the class of bolt and the bolt
length.
4. The use of the universal joint or the extension bar
somewhat reduces the fastening force of the impact
wrench. Compensate by fastening for a longer
period of time.
5. The manner of holding the tool or the material of
driving position to be fastened will affect the torque.
6. Operating the tool at low speed will cause a reduc-
tion in the fastening torque.

MAINTENANCE

CAUTION:
• Always be sure that the tool is switched off and the bat-
tery cartridge is removed before attempting to perform
inspection or maintenance.
• Never use gasoline, benzine, thinner, alcohol or the
like. Discoloration, deformation or cracks may result.
Replacing carbon brushes
Replace when they wear down to the limit mark. Keep
the carbon brushes clean and free to slip in the holders.
Both carbon brushes should be replaced at the same
time. Use only identical carbon brushes. (Fig. 13)
Use a screwdriver to remove two screws then remove
the rear cover. (Fig. 14)
Raise the arm part of the spring and then place it in the
recessed part of the housing with a slotted bit screw-
driver of slender shaft or the like. (Fig. 15)
Use pliers to remove the carbon brush cap of the carbon
brushes. Take out the worn carbon brushes, insert the
new ones and replace the carbon brush cap in reverse.
(Fig. 16)
Make sure to place the lead wire in opposite side of the
arm. (Fig. 17)
Put the lead wires between the spacer and the side of
brush holder. (Fig. 18)
Make sure that the carbon brush caps fit into the holes in
brush holders securely. (Fig. 19)
Reinstall the rear cover and tighten two screws securely.
To maintain product SAFETY and RELIABILITY, repairs,
any other maintenance or adjustment should be per-
formed by Makita Authorized Service Centers, always
using Makita replacement parts.