Chamberlain LiftMaster PROFESSIONAL SECURITY+ 3255-2CM Manuel Du Propriétaire page 8

INSTALLATION STEP 1
Determine the Header Bracket
Location
To prevent possible SERIOUS INJURY or DEATH:
• Header bracket MUST be RIGIDLY fastened to 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.
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
(1.22 m) 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 9)
when clearance is minimal. (It may be mounted on
the wall upside down if necessary, to gain
approximately 1/2" (1 cm).
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 9.
3. Open your door to the highest point of travel as shown.
Draw an inter secting horizontal line on the header wall
above the high point:
• 2" (5 cm) above the high point for sectional door and
one-piece door with track.
• 8" (20 cm) above the high point for one-piece door
without track.
This height will provide travel clearance for the top edge
of the door.
NOTE: If the total number of inches exceeds the height
available in your garage, use the maximum height
possible, or refer to page 9 for ceiling installation.
Header Wall
Header Wall
2" (5 cm)
Highest Point
of Travel
Door
Sectional door with curved track
Header Wall
8" (20 cm)
Highest
Door
Point
of Travel
Jamb
Hardware
One-piece door without track:
jamb hardware
8
Unfinished
Ceiling
2x4
Vertical Centerline
of Garage Door
2x4
Level
(optional)
Header Wall
Track
Door
One-piece door with horizontal track
Header Wall
8" (20 cm)
Door
One-piece door without track:
pivot hardware
OPTIONAL
CEILING
MOUNT
FOR
HEADER
BRACKET
Structural
Supports
2" (5 cm)
Track
Highest Point
of Travel
Highest
Point
of Travel
Pivot