Chamberlain HD900CD User Manual
8
ASSEMBLY STEP 1
Assemble the Rail & Install the Trolley
To avoid installation diffi culties, do not run the garage
door opener until instructed to do so.
door opener until instructed to do so.
The front rail has a cut out “window” at the door end
(see illustration). The hole above this window is larger on
the top of the rail than on the bottom. A smaller hole
3-1/2" (8.9 cm) away is close to the rail edge. Rotate the
back rail so it has a similar hole close to the opposite
edge, about 4-3/4" (12 cm) from the far end.
(see illustration). The hole above this window is larger on
the top of the rail than on the bottom. A smaller hole
3-1/2" (8.9 cm) away is close to the rail edge. Rotate the
back rail so it has a similar hole close to the opposite
edge, about 4-3/4" (12 cm) from the far end.
1. Remove the straight door arm and hanging bracket
packaged inside the front rail and set aside for
Installation Step 5 and 12. NOTE: To prevent INJURY
while unpacking the rail carefully remove the straight
door arm stored within the rail section.
Installation Step 5 and 12. NOTE: To prevent INJURY
while unpacking the rail carefully remove the straight
door arm stored within the rail section.
2. Align the rail sections on a fl at surface as shown and
slide the tapered ends into the larger ones. Tabs along
the side will lock into place.
the side will lock into place.
To prevent INJURY from pinching, keep hands and
fi ngers away from the joints while assembling the rail.
fi ngers away from the joints while assembling the rail.
3. Place the motor unit on packing material to protect
the cover, and rest the back end of the rail on top.
For convenience, put a support under the front end of
the rail.
For convenience, put a support under the front end of
the rail.
4. As a temporary stop, insert a screwdriver into the hole
10" (25 cm) from the front end of the rail, as shown.
5. Check to be sure there are 4 plastic wear pads inside
the inner trolley. If they became loose during shipping,
check all packing material. Snap them back into
position as shown.
check all packing material. Snap them back into
position as shown.
6. Slide the trolley assembly along the rail from the back
end to the screwdriver.
KEEP LARGER
HOLE ON TOP
HOLE ON TOP
FRONT RAIL
(TOP)
(TOP)
Screwdriver
Trolley
Front Rail
(TO DOOR)
(TO DOOR)
Back Rails
(TO MOTOR UNIT)
(TO MOTOR UNIT)
Outer Trolley
Inner Trolley
Wear Pads
Idler
Pulley
Hole
Pulley
Hole
Tabs
Tapered
End
End
Tapered
End
End
Tapered
End
End
Tapered
End
End
Window
Cut-Out
Cut-Out