Chamberlain HD920EV Owner's Manual page 19

Installation
STEP 9 Connect the door arm to the trolley
Installation will vary according to the garage door type. Follow the instructions which apply to your door.
OPTION A
SECTIONAL DOORS
IMPORTANT: The groove on the straight door arm MUST face away from the curved door arm.
1. Close the door. Disconnect the trolley by pulling the emergency release handle.
2. Attach the straight door arm to the outer trolley using the clevis pin. Secure with the ring
fastener.
3. Attach the curved door arm to the door bracket using the clevis pin. Secure with the ring
fastener.
4. Bring arm sections together. Find two pairs of holes that line up and join sections. Select holes
as far apart as possible to increase door arm rigidity and attach using the bolts, nuts, and lock
washers.
5. Pull the emergency release handle toward the garage door opener until the trolley release
arm is horizontal. The trolley will re-engage automatically when the garage door opener is
activated.
NOTE: If the holes in the curved door arm and the straight door arm do not align, reverse the straight
door arm, select two holes (as far apart as possible) and attach using bolts , nuts, and lock washers . If the
straight door arm is hanging down too far, you may cut 6 inches (15 cm) from the solid end.
Clevis Pin 5/16"x1-1/4"
Ring Fastener
Lock Washer
5/16" -18
HARDWARE
Clevis Pin 5/16"x1"
Hex Bolt 5/16"-18x7/8"
Nut 5/16"-18
CORRECT
Straight
Door Arm
(Groove
facing
out)
Ring Fastener
Lock Washer
5/16" -18
Nut
5/16"-18
18
INCORRECT
Straight
Door
Curved
Arm
Door
Arm
Clevis Pin
5/16"x1"
Hex Bolt 5/16"-18x7/8"
Clevis Pin 5/16"x1-1/4"
Curved
Door
Arm