Chamberlain WHISPER DRIVE HD900D - Manual (Page 10)

10
ASSEMBLY STEP 4
Install the Belt and Attach the Belt Cap Retainer
1. Pull the belt around the idler pulley and toward the trolley.
The ribbed side must contact the pulley.
2. Hook the trolley connector into the retaining slot on the trolley
as shown.
3. With the trolley against the screwdriver, dispense the
remainder of the belt along the rail length toward the motor
unit and around the belt pulley. The belt pulley teeth must
engage the belt.
4. Check to make sure the belt is not twisted and the FLAT side
of the trolley threaded shaft is facing the rail. Connect the
trolley threaded shaft with the master link, as illustrated:
• Push pins of master link bar through holes in end of belt
and trolley threaded shaft.
• Push master link cap over pins and past pin notches.
• Slide clip-on spring over cap and onto pin notches until
both pins are securely locked in place.
5. Insert the trolley threaded shaft through the hole in the
trolley. Be sure the belt is not twisted and the FLAT side of
the trolley threaded shaft faces the rail.
6. Hold the belt at the trolley shaft as you thread the spring nut
by hand onto the shaft until finger tight against the trolley.
DO NOT use any tools.
7. Remove the screwdriver.
8. Position the belt cap retainer over the motor unit belt pulley
as shown and fasten to the mounting plate with 8x3/8" hex
screws provided.
To avoid possible SERIOUS INJURY to fingers from moving
garage door opener:
• ALWAYS keep hand clear of belt pulley while operating
opener.
• Securely attach belt pulley cover BEFORE operating.
Hex Screw 8x3/8"
Spring Nut
Trolley
Connector
Idler Pulley
Retaining
Slot
Hole
Master Link
Clip-On Spring
Master Link Cap
Trolley
Threaded
Shaft Master
Link Bar
Pin
Notch
HARDWARE SHOWN ACTUAL SIZE
Spring/Trolley Nut
8x3/8" Hex Screws
Belt Cap
Retainer
Mounting
Plate
Motor Unit
Belt Pulley