Craftsman 139.18451DM Manuel D'instructions page 4

Planning
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
fi nd it helpful to refer back to this page and the accompanying
illustrations as you proceed with the installation of your opener.
Depending on your requirements, there are several installation
steps which may call for materials or hardware not included in the
carton.
• Installation Step 1 – Look at the wall or ceiling above the
garage door. The header bracket must be securely fastened to
structural supports.
• Installation Step 5 – Do you have a fi nished ceiling in your
garage? If so, a support bracket and additional fastening
hardware may be required.
• Installation Step 10 – Depending upon garage construction,
extension brackets or wood blocks may be needed to install
sensors.
• Installation Step 10 – Alternate fl oor mounting of the safety
reversing sensor will require hardware not provided.
• Do you have an access door in addition to the garage door? If
not, Model 18752 Emergency Key Release is required.
See Accessories page.
• Look at the garage door where it meets the fl oor. Any gap
between the fl oor and the bottom of the door must not exceed
1/4" (6 mm). Otherwise, the safety reversal system may not
work properly. See Adjustment Step 3. Floor or door should be
repaired.
SECTIONAL DOOR INSTALLATION
Horizontal and vertical reinforcement
is needed for lightweight garage doors
(fiberglass, steel, aluminum, door with
glass panels, etc.). See page 23 for details.
Vertical
Centerline
of Garage
Door
Safety Reversing Sensor
Header Wall
Safety Reversing
Gap between floor
Sensor
and bottom of door
must not exceed 1/4" (6 mm).
SECTIONAL DOOR INSTALLATIONS
• Do you have a steel, aluminum, fi berglass or glass panel
door? If so, horizontal and vertical reinforce ment is required
(Installation Step 11).
• The opener should be installed above the center of the door.
If there is a torsion spring or center bearing plate in the way of
the header bracket, it may be installed within 4 feet (1.22 m)
to the left or right of the door center. See Installation Steps
1 and 11.
• If your door is more than 7 feet (2.13 m) high, see rail extension
kits listed on Accessories page.
Slack in chain tension
is normal when garage
door is closed.
Extension Spring
OR
Torsion Spring
Wall-mounted
Access Door
Door Control
4
FINISHED CEILING
Support bracket &
fastening hardware
is required.
See page 16.
CLOSED POSITION
Header
Bracket
Rail Tab
Rail
Garage
Door
Spring
Straight
Door Arm
Curved
Header
Door Arm
Wall
Door
Garage
Bracket
Door
Motor unit
Trolley
Chain
Emergency
Release
Rope &
Handle