Chamberlain WHISPER DRIVE HD900D - Manual (Page 8)

8
FRONT RAIL
(TOP)
KEEP LARGER
HOLE ON TOP
ASSEMBLY STEP 1
Assemble the Rail & Install the Trolley
To avoid installation difficulties, do not run the garage door
opener until instructed to do so.
Front Rail
(TO DOOR)
Window
Cut-Out
Screwdriver
Idler
Pulley
Hole
Tabs
Back Rails
(TO MOTOR UNIT)
Trolley
Tapered
End
Tapered
End
Inner Trolley
Wear Pads
Outer Trolley
Tapered
End
Tapered
End
To prevent INJURY from pinching, keep hands and fingers
away from the joints while assembling the rail.
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 rai
l 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.
2. Align the rail sections on a flat surface as shown and slide the
tapered ends into the larger ones. Tabs along the side will lock
into place.
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.
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.
6. Slide the trolley assembly along the rail from the back end to
the screwdriver.