DeWalt DCD791 Guide D'utilisation page 75

mode will work as a screwdriver in light applications, before hesitating
as the screw head reaches the work piece, and then (if required) start
a slow controlled impact to ensure the head ends perfectly flush.
This mode is for light duty screwdriving applications. If the tool
NOTE:
will not drive a fastener in Precision Mode, please select mode 2 which
will give the additional power required.
DCF887
Mode 1 Precision Drive
Mode 2 Normal Impacting
Mode 3 High Speed Impacting
FIG. 8
K
Usage
Your impact tool can generate the following maximum torque:
Mode Ft.-Lbs.
1 20
2 125
3 152
rpm 0–1000
rpm 0–2800
rpm 0–3250
In.-Lbs. Nm
240 27
1500 170
1825 205
CAUTION: Ensure fastener and/or system will withstand the level of
torque generated by the tool. Excessive torque may cause breakage
and possible personal injury.
1. Place the accessory on the fastener head. Keep the tool pointed
straight at the fastener.
2. Press switch to start operation. Release switch to stop operation.
Always check torque with a torque wrench, as the fastening torque
is affected by many factors including the following:
• Voltage: Low voltage, due to a nearly discharged battery, will
reduce fastening torque.
• Accessory size: Failure to use the correct accessory size will
cause a reduction in fastening torque.
• Bolt size: Larger bolt diameters generally require higher
fastening torque. Fastening torque will also vary according to
length, grade, and torque coefficient.
• Bolt: Ensure that all threads are free of rust and other debris to
allow proper fastening torque.
• Material: The type of material and surface finish of the material
will affect fastening torque.
• Fastening time: Longer fasten ing time results in increased
fastening torque. Using a longer fastening time than
recommended could cause the fasteners to be overstressed,
stripped or damaged.
MAINTENANCE
WARNING: To reduce the risk of serious personal injury,
place the forward/reverse button in the lock-off position or
turn tool off and disconnect battery pack before making any
adjustments or removing/installing attachments or accessories.
An accidental start-up can cause injury.
13