LiftMaster 3840 3840 Manual - Page 21

INSTALLATION STEP 14 Connect Door Arm to Trolley Follow instructions which apply to your door type as illustrated below and on the following page. SECTIONAL DOORS ONLY Make sure garage door is fully closed. Pull the emergency release handle to disconnect the outer trolley from the inner trolley. Slide the outer trolley back (away from the door) about 2" (5 cm) as shown in Figures 1, 2 and 3. Figure 1: • Fasten straight door arm section to outer trolley with the 5/16"x1" clevis pin. Secure the connection with a ring fastener. • Fasten curved section to the door bracket in the same way, using the 5/16"x1-1/4" clevis pin. Figure 2: • Bring arm sections together. Find two pairs of holes that line up and join sections. Select holes as far apart as possible to increase door arm rigidity. Figure 3, Hole alignment alternative: • If holes in curved arm are above holes in straight arm, disconnect straight arm. Cut about 6" (15 cm) from the solid end. Reconnect to trolley with cut end down as shown. • Bring arm sections together. • Find two pairs of holes that line up and join with bolts, lock washers and nuts. Pull the emergency release handle toward the opener at a 45° angle so that the trolley release arm is horizontal. Proceed to Adjustment Step 1, page 23. Trolley will re-engage automatically when opener is operated. Inner Trolley Outer Trolley Figure 1 Ring Fastener Straight Door Arm Door Bracket Clevis Pin 5/16"x1" Emergency Release Handle Curved Door Arm Clevis Pin 5/16"x1-1/4" Nuts 5/16"-18 Lock Washers 5/16" Figure 2 Door Bracket Bolts 5/16"-18x7/8" HARDWARE SHOWN ACTUAL SIZE Nut 5/16"-18 Lock Washer 5/16" Ring Fastener Clevis Pin 5/16"x1" (Trolley) Clevis Pin Hex Bolt 5/16"x1-1/4" (Door Bracket) 5/16"-18x7/8" Nuts 5/16"-18 Lock Washers 5/16" Figure 3 Bolts 5/16"-18x7/8" Cut this end 21