LiftMaster 3840 3840 Manual - Page 12

INSTALLING THE BRACKETS Be sure power to the opener is disconnected. Install and align the brackets so the sensors will face each other across the garage door, with the beam no higher than 6" (15 cm) above the floor. They may be installed in one of three ways, as follows: Garage door track installation (preferred): • Slip the curved arms over the rounded edge of each door track, with the curved arms facing the door. Snap into place against the side of the track. It should lie flush, with the lip hugging the back edge of the track, as shown in Figure 1. If your door track will not support the bracket securely, wall installation is recommended. Wall installation (Figures 2 & 3): • Place the bracket against the wall with curved arms facing the door. Be sure there is enough clearance for the sensor beam to be unobstructed. • If additional depth is needed, an extension bracket (see Accessories) or wood blocks can be used. • Use bracket mounting holes as a template to locate and drill (2) 3/16" diameter pilot holes on the wall at each side of the door, no higher than 6" (15 cm) above the floor. • Attach brackets to wall with lag screws (not provided). • If using extension brackets or wood blocks, adjust right and left assemblies to the same distance out from the mounting surface. Make sure all door hardware obstructions are cleared. Floor installation (Figure 4): • Use wood blocks or extension brackets (see Accessories) to elevate sensor brackets so the lenses will be no higher than 6" (15 cm) above the floor. • Carefully measure and place right and left assemblies at the same distance out from the wall. Be sure all door hardware obstructions are cleared. • Fasten to the floor with concrete anchors as shown. Figure 1 DOOR TRACK MOUNT (RIGHT SIDE) Door Track Lip Indicator Light Safety Reversing Sensor Bracket Lens Figure 2 WALL MOUNT (RIGHT SIDE) IGWnasairldal ege Fasten Wood Block to Wall with Lag Screws (Not Provided) Indicator Light Safety Reversing Sensor Bracket Lag Screws (Not Provided) Lens Figure 3 WALL MOUNT (RIGHT SIDE) IGWnasairldal ege Extension Bracket (See Accessories) (Provided with Extension Bracket) (Provided with Extension Bracket) Safety Reversing Sensor Bracket Indicator Lens Light Figure 4 FLOOR MOUNT (RIGHT SIDE) IGWnsaairdlalege Lens Attach with Concrete Anchors (Not Provided) Indicator Light Safety Reversing Sensor Bracket 12