Chamberlain LiftMaster PROFESSIONAL SECURITY+ 2500DC Manuel D'instructions page 13

INSTALLATION STEP 5
Hang the Opener
Three representative installations are shown. Yours
may be different. Hanging brackets should be
angled, Figure 1, to provide rigid support. On
finished ceilings, Figure 2, attach a sturdy metal
bracket to structural supports before installing the
opener. This bracket and fastening hardware are not
provided.
Existing brackets from a previous installation may be
fastened to the sides of the motor unit as in Figures
1 and 2, or to the mounting tabs as shown in
Figure 3. Then continue with step 5 below.
1. Measure the distance from each side of the motor
unit to the structural support.
2. Cut both pieces of the hanging bracket to required
lengths.
3. Drill 3/16" pilot holes in the structural supports.
4. Attach one end of each bracket to a support with
5/16"-18x1-7/8" lag screws.
5. Fasten the opener to the hanging brackets with
5/16"-18x7/8" hex bolts, lock washers and nuts.
6. Check to make sure the rail is centered over the
door (or in line with the header bracket if the
bracket is not centered above the door).
7. Remove the 2x4. Operate the door manually. If
the door hits the rail, raise the header bracket.
8. Grease the top and underside of the rail surface
where the trolley slides with rail grease.
HARDWARE SHOWN ACTUAL SIZE
Lag Screw 5/16"-18x1-7/8"
Hex Bolt
5/16"-18x7/8" Lock Washer 5/16"
Nut 5/16"-18
WARNING
To avoid possible SERIOUS INJURY from a falling
garage door opener, fasten it SECURELY to structural
CAUTION
supports of the garage. Concrete anchors MUST be used
if installing any brackets into masonry.
Figure 1
Measure
Distance
Hex Bolts
5/16"-18x7/8"
Lock Washers 5/16"
Nuts 5/16"-18
Figure 2
Hidden
Support
Bracket
(Not Provided)
Hex Bolts
5/16"-18x7/8"
Lock Washers 5/16"
Nuts 5/16"-18
Preferred range of
bracket placement
Figure 3
Existing Brackets
Bracket
(Provided)
Utilizing existing top mount installation
13
Lag Screws
5/16"- 18x1-7/8"
Preferred range of
bracket placement
— FINISHED CEILING —
Lag Screws
5/16"-18x1-7/8"
(Not Provided)
Hex Bolts
5/16"-18x7/8"
Lock Washers 5/16"
Nuts 5/16"-18
Structural
Supports