Chamberlain 3255-2M 1/2 HP ユーザーズマニュアル

4

Identify the type and height of your garage door. Survey 

your garage area to see if any of the conditions below 

apply to your installation. Additional materials may be 

required. You may find it helpful to refer back to this 

page and the accompanying illustrations as you proceed 

with the installation of your opener.

Safety Reversing Sensor

Horizontal and vertical reinforcement
is needed for lightweight garage doors
(fiberglass, steel, aluminum,
door with glass panels, etc.).
See page 19 for details.

 — — —        — — —        — —

Header Wall

Safety
Reversing
Sensor

Gap between floor and bottom of door
 must not exceed 1/4" (6 mm).

Extension Spring

Torsion Spring

Access Door

OR

Slack in chain tension
is normal when
garage door is closed.

Wall-
mounted
Door 
Control

Motor Unit

FINISHED CEILING

Support bracket & 
fastening hardware
is required.
See page 12.

Vertical Centerline 
of Garage Door

FINISHED CEILING

Support bracket
& fastening
hardware is required.
See page 12.

Slack in chain tension
is normal when
garage door is closed.

Safety
Reversing Sensor

Header
Wall

Access 
Door

Safety 
Reversing Sensor

Gap between floor and bottom of
door must not exceed 1/4" (6 mm).

Wall-mounted
Door Control

Motor Unit

Access
Door

Safety
Reversing 
Sensor

Safety 
Reversing 
Sensor

Slack in chain tension is normal when 
garage door is closed.

Gap between floor and 
bottom of door must 
not exceed 1/4" (6 mm).