Chamberlain 3255-2M 1/2 HP Manual De Usuario

6

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.

 •  Position chain over the sprocket. If necessary, loosen 

the outer nut on the trolley to obtain more chain slack.

•  Insert the second washered bolt.

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 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.

To avoid SERIOUS damage to garage door opener, use ONLY 
those bolts/fasteners mounted in the top of the opener.

Washered Bolt 
5/16"-18x1/2"

Styrofoam

Rail
Hole

Washered Bolts
5/16"-18x1/2"

Sprocket

Mounting
Plate

Front Tab Slot

Back Tab Slot

Sprocket Cover