Kobalt K20LW-26A Manual page 9

OPERATING INSTRUCTIONS
Tightening Fasteners
WARNING: Battery tools are always in operating condition. Therefore, the direction-of-rotation
selector should always be locked when not in use or carrying at your side.
Tighten fasteners with the impact wrench. The proper fastening torque may differ depending on the
type or size of the bolt, the material of the workpiece to be fastened, etc. Before starting your job,
always perform a test operation to determine the proper fastening time for your bolt or nut.
a. Check the direction-of-rotation selector for the correct setting (forward or reverse).
b. Hold the tool firmly and place the socket over the bolt or nut.
c. Depress the trigger switch to turn the impact wrench on. The variable-speed trigger switch
delivers higher speed with increased trigger pressure and lower speed with decreased trigger
pressure.
d. Fasten the bolt or nut to the proper torque.
e. To turn the impact wrench OFF, release the trigger switch.
f. After fastening, always check the torque with a torque wrench.
NOTICE: Hold the tool straight along the axis of the bolt or nut.
NOTICE: Excessive fastening torque may damage the bolt/nut or socket.
Practice with various fasteners, noting the length of time required to reach the desired torque. Check
the tightness with a torque wrench. If the fasteners are too tight, reduce the impacting time. If they are
not tight enough, increase the impacting time.
The fastening torque is affected by a wide variety of factors, including the following:
• 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.
• Bolt
— Although the torque coefficient and the class of bolt may be the same, the proper fastening
torque will differ according to the diameter of the bolt. Although the diameters of bolts may be
the same, the proper fastening torque will differ according to the torque coefficient, the class
of bolt and the bolt length.
• The use of a universal joint or an extension bar (both available separately) will reduce the fastening
force of the impact wrench somewhat. Compensate by fastening for a longer period of time.
• The manner of holding the tool or the material to be fastened will affect the torque.
Loosening Fasteners
The torque that is required to loosen a fastener averages 75% to 80% of the tightening torque,
depending on the condition of the contacting surfaces. However, if rust or corrosion causes seizing,
more torque may be required.
9