LiftMaster 3840 3840 Manual - 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 find it helpful to refer back to this page and the accompanying illustrations as you proceed with the installation of your opener. SECTIONAL DOOR INSTALLATION 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 FINISHED CEILING Support bracket & fastening hardware is required. See page 15. Rail Extension Torsion OR Spring Spring Motor Unit Vertical Centerline of Garage Door Wall- mounted Door Access Door Control --- --- -- Safety Reversing Sensor Safety Reversing Sensor Gap between floor and bottom of door must not exceed 1/4" (6 mm). ONE-PIECE DOOR WITHOUT TRACK FINISHED CEILING Rail Support bracket & fastening hardware is required. See page 159. Motor Unit Header Wall Access Door Wall-mounted Door Control ONE-PIECE DOOR WITH TRACK Header Wall Access Door Safety Reversing Sensor Safety Reversing Gap between floor Sensor and bottom of door must not exceed 1/4" (6 mm). Safety Reversing Sensor Safety Gap between floor Reversing Sensor and bottom of door must not exceed 1/4" (6 mm). 4