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15
1 609 929 K31 • 12.12.06
Operation
Method of Operation
The tool holder
1
with the tool is driven by an electric
motor via a gear and impact mechanism.
The working procedure is divided into two phases:
Screwing in
and
tightening
(impact mechanism in
action).
The impact mechanism is activated as soon as the
screwed connection runs tight and thus load is put on
the motor. In this instance, the impact mechanism
converts the power of the motor to steady rotary
impacts. When loosening screws or nuts, the process
is reversed.
Starting Operation
Inserting the Battery
f
Use only original Bosch O-pack batteries
with the voltage given on the type plate of
your machine.
The use of other batteries can
lead to injuries and danger of fire.
Set the rotational direction switch
5
to the centre posi-
tion in order to avoid unintentional starting. Insert the
charged battery
4
into the handle so that it can be felt
to engage and faces flush against the handle.
Reversing the Rotational Direction
(see figure C)
The rotational direction switch
5
is used to reverse the
rotational direction of the machine. However, this is
not possible with the On/Off switch
6
actuated.
Right rotation:
For driving in screws and tightening
nuts, press the rotational direction switch
5
through to
the left stop.
Left Rotation:
For loosening and unscrewing screws
and nuts, press the rotational direction switch
5
through to the right stop.
Switching On and Off
To
start
the machine, press the On/Off switch
6
and
keep it depressed.
To switch off the machine,
release
the On/Off switch
6
.
Adjusting the Speed
The speed of the switched on power tool can be vari-
ably adjusted, depending on how far the On/Off
switch
6
is pressed.
Light pressure on the On/Off switch
6
results in a low
rotational speed. Further pressure on the switch
results in an increase in speed.
Operating Instructions
f
Apply the power tool to the screw/nut only
when it is switched off.
Rotating tool inserts can
slip off.
The torque depends on the impact duration. The max-
imum achieved torque results from the sum of all indi-
vidual torques achieved through impact. The
maximum torque is achieved after an impact duration
of 6–10 seconds. After this duration, the tightening
torque is increased only minimally.
The impact duration is to be determined for each
required tightening torque. The actually achieved
tightening torque is always to be checked with a
torque wrench.
Screw Applications with Hard, Spring-loaded or
Soft Seat
When in a test, the achieved torques in an impact
series are measured and transferred into a diagram,
resulting in the curve of a torque characteristic. The
height of the curve corresponds with the maximum
reachable torque, and the steepness indicates the
duration in which this is achieved.
A torque gradient depends on the following factors:
•
Strength properties of the screws/nuts
•
Type of backing (washer, disc spring, seal)
•
Strength properties of the material being
screwed/bolted together
•
Lubrication conditions at the screw/bolt connec-
tion
The following application cases result accordingly:
•
A
hard seat
is given for metal-to-metal screw
applications with the use of washers. After a rela-
tively short impact duration, the maximum torque is
reached (steep characteristic curve). Unnecessary
long impact duration only causes damage to the
machine.
•
A
spring-loaded seat
is given for metal-to-metal
screw applications, however with the use of spring
washers, disc springs, studs or screws/nuts with
conical seat as well as when using extensions.
•
A
soft seat
is given for screw applications, e. g.,
metal on wood or when using lead washers or fibre
washers as backing.
For a spring-loaded seat as well as for a soft seat, the
maximum tightening torque is lower than for a hard
seat. Also, a clearly longer impact duration is required.
OBJ_BUCH-246-001.book Page 15 Tuesday, December 12, 2006 3:35 PM
