LiftMaster 8550WLB Owners Manual - Page 11
Attach the Chassis Support Bracket, Tighten the Chain, Do not, overtighten, Model 8580WLB Only
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Assembly 2 Attach the Chassis Support Bracket MODELS 8587W, 8587WL, AND 8580WLB To avoid possible SERIOUS INJURY to finger from moving garage door opener: l ALWAYS keep hand clear of sprocket while operating opener. l Securely attach sprocket cover BEFORE operating. 3 Tighten the Chain 1. Loosen the inner nut and lock washer on the trolley threaded shaft. 2. Tighten the outer nut until the chain is a 1/2" above the base of the rail at the midpoint of the rail. 3. Re-tighten the inner nut. Slack in the chain is normal when the door is closed. No readjustment is necessary. Model 8580WLB Only: If the tension is not correct with a 7' rail installed, remove two links from the chain to set the correct tension. 1. Position the chassis support bracket on the unit. 2. Attach the bracket to the rail with 1/4"-20 x 5/8" hex bolts and lock washers. Do not overtighten. 3. Attach the bracket to the opener by inserting a 5/16"-18 x 1/2" washered screw through a hole in each side flange and a matching hole in the bracket. Complete the connection by inserting the #8-32 x 3/8" screw through the back flange and the hole in rail support. Lock Washer Hex Bolt 1/4"-20x5/8" Screw #8-32x3/8" Washerd Bolt 5/16"-18x1/2" 1/2" (13 mm) 11
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