Chamberlain LiftMaster PROFESSIONAL SECURITY+ 2500C Manuel Du Propriétaire page 8

INSTALLATION STEP 1
Determine the Header Bracket
Location
WARNING
To prevent possible SERIOUS INJURY or DEATH:
• Header bracket MUST be RIGIDLY fastened to
CAUTION
structural support on header wall or ceiling, otherwise
garage door might not reverse when required. DO NOT
install header bracket over drywall.
• Concrete anchors MUST be used if mounting header
bracket or 2x4 into masonry.
• NEVER try to loosen, move or adjust garage door,
springs, cables, pulleys, brackets, or their hardware, all
of which are under EXTREME tension.
• ALWAYS call a trained door systems technician if
garage door binds, sticks, or is out of balance. An
unbalanced garage door might not reverse when
required.
Installation procedures vary according to garage door
types. Follow the instructions which apply to your
door.
SECTIONAL DOOR
AND ONE-PIECE DOOR WITH TRACK
1. Close the door and mark the inside vertical
centerline of the garage door.
2. Extend the line onto the header wall above the
door.
You can fasten the header bracket within 4 feet
of the left or right of the door center only if a
torsion spring or center bearing plate is in the
way; or you can attach it to the ceiling (see
page 10) when clearance is minimal. (It may be
mounted on the wall upside down if necessary,
to gain approximately 1/2".)
If you need to install the header bracket on a 2x4
(on wall or ceiling), use lag screws (not provided)
to securely fasten the 2x4 to structural supports as
shown here and on page 10.
3. Open your door to the highest point of travel as
shown. Draw an intersecting horizontal line on the
header wall 2" above the high point. This height
will provide travel clearance for the top edge of the
door.
Proceed to Step 2, page 10.
Header
Wall
Ceiling
Header Wall
2"
Highest Point
of Travel
Door
One-piece
door with
horizontal
track
8
Finished
Vertical
Ceiling
Centerline
Structural
2x4
Supports
WARNING
WARNING
Vertical
Centerline
Track
Sectional door
with curved
track
Header Wall
2"
Highest Point
of Travel
Door
Track