Chamberlain 4142DC Owner's Manual page 28

ALL ONE-PIECE DOORS
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 33.
• 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
Outer Trolley
Door Arm
Connector Hole
Door Arm
Closed
Door
Inner Trolley
Correct Angle
Open Door
Door
Bracket
Clevis Pin
Straight
5/16"x1-1/4"
Arm
Bolts
5/16"-18x7/8
Emergency Release Handle
Door Arm
Door with
Backward Slant (Incorrect)
28
Ring
Fastener
Nuts
Lock
5/16"-18
Washers
5/16"
Outer Trolley
Curved
Door Arm