Assembly For Model: 8155W - Chamberlain Contractor Series Manual

Assembly for Model: 8155W

1 Attach the Rail to the Garage Door Opener
To avoid possible SERIOUS INJURY to finger from moving garage door opener:
ALWAYS keep hand clear of sprocket while operating opener.
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Securely attach sprocket cover BEFORE operating.
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To avoid SERIOUS damage to garage door opener, use ONLY those bolts/fasteners
mounted in the top of the opener.
NOTE: ONLY use the bolts removed from the garage door opener. Place the garage door
opener on the packing material to prevent scratching.
1. Remove the two bolts from the top of the garage door opener.
2. Align the rail and the styrofoam over the sprocket. Cut the tape from the rail, belt,
and styrofoam.
3. Fasten the rail with the previously removed bolts.
4. Position the belt around the garage door opener sprocket.
5. Attach the sprocket cover over the garage door opener sprocket and attach with
hex screws.
Washered Bolts
5/16"-18 x 1/2"
(Mounted in
door opener)
Hex Screws 8 x 3/8"
Sprocket
Cover
the garage
2 Tighten the Belt
1. By hand, thread the spring trolley nut on the threaded shaft until it is finger tight
against the trolley. Do not use any tools.
2. Insert a flathead screwdriver tip into one of the nut ring slots and brace it firmly
against the trolley.
3. Tighten the spring trolley nut with an adjustable wrench or a 7/16" open end
wrench about a quarter turn until the spring releases and snaps the nut ring
against the trolley. This sets the spring to optimum belt tension.
1
Spring Trolley Nut
2
Nut ring
slot
3
Nut Ring
BEFORE
1"
(2.5 cm)
9
(To motor unit)
Nut Ring
AFTER RELEASE
1-1/4"
(3.18 cm)