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ENGLISH
tool. The centre position of the control button locks the trigger
switch in the off position. When changing the position of the
control button, be sure the trigger isreleased.
NOTE: The first time the tool is run after changing the direction
of rotation, you may hear a click on start up. This is normal and
does not indicate aproblem.
Worklights (Fig. A)
There are three worklights
7
located around the 6.35 mm hex
chuck
4
. The worklights are activated when the trigger switch
isdepressed.
When the trigger is released, the worklight will stay illuminated
for up to 20seconds.
NOTE: The worklights are for lighting the immediate work
surface and are not intended to be used as aflashlight.
Mode Selector (Fig. A, D)
Your tool is equipped with a mode selector
11
which allows
you to select one of three modes. Select the mode based on the
application and control the speed of the tool using the variable
speed trigger switch
1
.
Precision Drive (Fig. D)
In addition to normal impacting modes, this tool features the
Precision Drive mode which enables greater control in lighter
applications to avoid damage to materials or fasteners. It is ideal
for light applications such as cabinet hinge screws or machine
screws. Precision Drive 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 perfectlyflush.
NOTE: This mode is for light duty screwdriving applications. If
the tool will not drive a fastener in Precision Mode, please select
mode 2 which will give the additional powerrequired.
DCF850
Mode 1 Precision Drive rpm 0–1000
Mode 2 Normal Impacting rpm 0–2800
Mode 3 High Speed Impacting rpm 0–3250
Quick-Release Chuck (Fig. A, E, F)
WARNING: Use only impact accessories. Non-impact
accessories may break and cause a hazardous condition.
Inspect accessory prior to use to ensure that it con tains
nocracks.
NOTE: The chuck accepts 6.35 mm hex accessoriesonly.
Place the forward/reverse button
2
in the lock-off (centre)
position or remove battery pack before changingaccessories.
To install an accessory, fully insert the accessory. The accessory is
locked into place (Fig.E).
To remove an accessory, pull the chuck collar
3
away from the
front of the tool. Remove the accessory (Fig.F).
Usage
Your impact tool generates the following maximum torque:
Cat # Nm
DCF850 206.2
CAUTION: Ensure fastener and/or system will withstand
the level of torque generated by the tool. Excessive torque
may cause breakage and possible personalinjury.
1. Place the accessory into the chuck. Keep the tool pointed
straight at the workpiece.
2. Press switch to start operation. Release the 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 fasteningtorque.
- Socket size: Failure to use the correct socket size will
cause a reduction in fasteningtorque.
- Bolt Size: Larger bolt diameters generally require
higher fastening torque. Fastening torque will also vary
according to length, grade, and torquecoefficient.
- Bolt: Ensure that all threads are free of rust and other
debris to allow proper fasteningtorque.
- Material: The type of material and surface finish of the
material will affect fasteningtorque.
- 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 ordamaged.
MAINTENANCE
Your DeWALT power tool has been designed to operate
over a long period of time with a minimum of maintenance.
Continuous satisfactory operation depends upon proper tool
care and regularcleaning.
WARNING: To reduce the risk of serious personal
injury, turn tool off and disconnect battery pack
before making any adjustments or removing/
installing attachments or accessories. An accidental
start-up can causeinjury.
The charger and battery pack are notserviceable.
Lubrication
Your power tool requires no additionallubrication.
Cleaning
WARNING: Blow dirt and dust out of the main housing
with dry air as often as dirt is seen collecting in and around
the air vents. Wear approved eye protection and approved
dust mask when performing thisprocedure.
WARNING: Never use solvents or other harsh chemicals
for cleaning the non-metallic parts of the tool. These
chemicals may weaken the materials used in these parts.
Use a cloth dampened only with water and mild soap.