Chamberlain LiftMaster Security + 3270 1/2 HP Manuel D'instructions page 10

INSTALLATION STEP 3
Attach the Rail to the Header Bracket
1. Position the opener on the garage fl oor below the
header bracket. Use packing material as a protective
base. NOTE: If the door spring is in the way you'll need
help. Have someone hold the opener securely on a
temporary support to allow the rail to clear the spring.
2. Position the rail bracket against the header bracket.
3. Align the bracket holes and join with a clevis pin
as shown.
4. Insert a ring fastener to secure.
HARDWARE
SHOWN
ACTUAL SIZE
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 fl at is convenient for setting an ideal
door-to-rail distance.
1. Raise the opener onto a stepladder. You will need help
at this point if the ladder is not tall enough.
2. Open the door all the way and place a 2x4 laid fl at on
the top section beneath the rail.
3. 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.
1. Raise the opener onto a stepladder. You will need help
at this point if the ladder is not tall enough.
2. Open the door all the way and place a 2x4 on its side on
the top section of the door beneath the rail.
3. 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.
Clevis Pin 5/16"x2-3/4"
Trolley
Release Arm
RELEASED
Header Wall
Header Bracket
Belt Pulley
Bracket
Garage Door
To prevent damage to garage door, rest garage door
opener rail on 2x4 placed on top section of door.
Door
Header Bracket
Top of Door
10
Ring
Header
Fastener
Bracket
Clevis Pin
5/16"x2-3/4"
Belt Pulley
Bracket
Rail
Temporary
Support
Rail
2x4 is used to determine
the correct mounting
height from ceiling.
2x4 is used to determine
the correct mounting
height from ceiling.
Ring
Fastener