Chamberlain LiftMaster Security+ 2500B Owner's Manual page 23

ALL ONE-PIECE DOORS
1. Assemble the Door Arm:
• Fasten the straight and curved door arm sections
together to the longest possible length (with a 2
or 3 hole overlap).
• Make sure the garage door is fully closed.
Connect the straight door arm section to the door
bracket with the 5/16"x1-1/4" clevis pin.
• Secure with a ring fastener.
• Pull the emergency release handle,
disconnecting the outer trolley from the inner
trolley by pulling straight down on the emergency
release handle and sliding the outer trolley back
toward the motor unit.
• Connect the curved door arm section to the
trolley using the 5/16"x1-1/4" clevis pin and ring
fastener.
NOTE: Adjusting the limits on the following page:
• The trolley will automatically connect. If not,
review the trolley lockout feature on page 28.
• When setting the up limit on the following page,
the door should not have a "backward" slant
when fully open as illustrated below. A slight
backward slant will cause unnecessary bucking
and/or jerking operation as the door is being
opened or closed from the fully open position.
Inner Trolley
Door Arm
Closed
Door
Outer Trolley
Emergency Release Handle
Inner Trolley
Correct Angle
Open Door
Door
Bracket
Clevis Pin Straight
5/16"x1-1/4" Arm
Bolts
5/16"-18x7/8
Door with
Backward Slant
(Incorrect)
23
Ring
Fastener
Nuts
Lock
5/16"-18
Washers
5/16"
Outer Trolley
Curved
Door Arm