Chamberlain WHISPER DRIVE 248754 - Manual (Page 11)

11
ASSEMBLY STEP 5
Set the Tension
• Insert a screwdriver tip into one of the nut ring slots
and brace it fi rmly against the trolley.
• Place a 7/16" open end wrench on the square end.
Rotate the nut about 1/4 turn until the spring releases
and snaps the nut ring against the trolley.
This sets the spring to optimum belt tension.
You have now fi nished assembling your garage door
opener. Please read the following warnings before
proceeding to the installation section.
Nut Ring Nut Ring
Trolley
Square
End
Square
End
BEFORE
1"
(2.5 cm)
AFTER RELEASE
1-1/4"
(3.18 cm)
Nut
Ring
Slot
IMPORTANT INSTALLATION INSTRUCTIONS
To reduce the risk of SEVERE INJURY or DEATH:
WARNING WARNING
1. READ AND FOLLOW ALL INSTALLATION WARNINGS
AND INSTRUCTIONS.
2. Install garage door opener ONLY on properly
balanced and lubricated garage door. An improperly
balanced door may NOT reverse when required and
could result in SEVERE INJURY or DEATH.
3. ALL repairs to cables, spring assemblies and other
hardware MUST be made by a trained door systems
technician BEFORE installing opener.
4. Disable ALL locks and remove ALL ropes connected
to garage door BEFORE installing opener to avoid
entanglement.
5. Install garage door opener 7 feet (2.13 m) or more
above fl oor.
6. Mount the emergency release within reach, but at
least 6 feet (1.8 m) above the fl oor and avoiding
contact with vehicles to avoid accidental release.
7. NEVER connect garage door opener to power source
until instructed to do so.
8. NEVER wear watches, rings or loose clothing while
installing or servicing opener. They could be caught
in garage door or opener mechanisms.
9. Install wall-mounted garage door control:
• within sight of the garage door.
• out of reach of children at minimum height
of 5 feet (1.5 m).
• away from ALL moving parts of the door.
10. Place entrapment warning label on wall next to
garage door control.
11. Place manual release/safety reverse test label in
plain view on inside of garage door.
12. Upon completion of installation, test safety reversal
system. Door MUST reverse on contact with a
1-1/2" (3.8 cm) high object (or a 2x4 laid fl at) on
the fl oor.
13. To avoid SERIOUS PERSONAL INJURY or DEATH
from electrocution, disconnect ALL electric and
battery power BEFORE performing ANY service or
maintenance.
INSTALLATION