Chamberlain LiftMaster PROFESSIONAL SECURITY+ 3255-2CM Manuel Du Propriétaire page 6

ASSEMBLY STEP 1
Attach the Rail to the Motor Unit
To avoid installation difficulties, do not run the garage
door opener until instructed to do so.
• Remove the two washered bolts mounted in top of
motor unit.
• Position rail at a 45˚ angle to opener so one hole in rail
and motor unit line up.
• Thread one of the washered bolts part way in.
Use only these bolts! Use of any other bolts will cause
serious damage to door opener.
• Align rail and styrofoam over sprocket. Cut tape from
rail, chain and styrofoam.
• REMOVE STYROFOAM.
ASSEMBLY STEP 2
Attach the Chain to the Sprocket and
Install the Sprocket Cover
• Position chain over the sprocket. If necessary, loosen
the outer nut on the trolley to obtain more chain slack.
• Insert the second washered bolt. CAUTION: Use only
the bolt previously removed from motor unit!
• Tighten both bolts securely through the rail into the
motor unit as shown.
• Install the sprocket cover: Insert the back tab in the slot.
Squeeze the cover slightly and insert the front tab in the
slot on the mounting plate.
To avoid SERIOUS damage to garage door opener, use ONLY
those bolts/fasteners mounted in the top of the opener.
USE ONLY THIS
TYPE AND SIZE
BOLT
To avoid possible SERIOUS INJURY to fingers from moving
garage door opener:
• ALWAYS keep hand clear of sprocket while operating opener.
• Securely attach sprocket cover BEFORE operating.
USE ONLY THIS
TYPE AND SIZE
BOLT
Sprocket Cover
Front Tab Slot
Mounting
Plate
6
Washered Bolt
5/16"-18x1/2"
Styrofoam
Rail
Hole
Washered Bolts
5/16"-18x1/2"
Sprocket
Back Tab Slot