Chamberlain LiftMaster PROFESSIONAL SECURITY+ 3255-2CM Manuel Du Propriétaire page 11

INSTALLATION STEP 4
Position the Opener
Follow instructions which apply to your door type as
illustrated.
SECTIONAL DOOR OR ONE-PIECE DOOR WITH
TRACK
A 2x4 laid flat is convenient for setting an ideal door-to-rail
distance.
• Remove foam packaging.
• Raise the opener onto a stepladder. You will need help
at this point if the ladder is not tall enough.
• Open the door all the way and place a 2x4 laid flat on
the top section beneath the rail.
• If the top section or panel hits the trolley when you raise
the door, pull down on the trolley release arm to
disconnect inner and outer sections. Slide the outer
trolley toward the motor unit. The trolley can remain
disconnected until Installation Step 12 is completed.
ENGAGED
ONE-PIECE DOOR WITHOUT TRACK
A 2x4 on its side is convenient for setting an ideal
door-to-rail distance.
• Remove foam packaging.
• Raise the opener onto a stepladder. You will need help
at this point if the ladder is not tall enough.
• Open the door all the way and place a 2x4 on its side
on the top section of the door beneath the rail.
• The top of the door should be level with the top of the
motor unit. Do not position the opener more than 4"
(10 cm) above this point.
Trolley
Release Arm
RELEASED
To prevent damage to garage door, rest garage door opener
rail on 2x4 placed on top section of door.
Door
11
Rail
2x4 is used to determine
the correct mounting height
from ceiling.
Header
Bracket
Top of Door
2x4 is used to determine
the correct mounting height
from ceiling.