Chamberlain 1270LMC - Manual (Page 23)

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).
• With the door closed, connect the straight door
arm section to the door bracket with a clevis pin.
• Secure with a ring fastener.
Nuts
5/16"-18 Lock
Washers
5/16"
Ring
Fastener
Straight
Door Arm
Screws
5/16"-18x7/8"
Door
Bracket
Clevis Pin
Curved
Door Arm
On one-piece doors, before connecting the door arm to the trolley the travel limits must be adjusted. Limit
adjustment screws are located on the left side panel as shown on page 24. Follow adjustment procedures
below.
Fully Open
Trolley
Door Arm
Connector Hole
Door Arm
Closed
Door Open Door
Door with
Backward Slant
Door Arm
Connector Hole
Fully Closed
Trolley
Door Arm
Adjustment Procedures for One-Piece Doors
Open Door Adjustment:
Decrease UP limit
• Turn the UP limit adjustment screw counter-
clockwise 5-1/2 turns.
• Press the Door Control push bar. The trolley will
travel to the fully open position.
• Manually raise the door to the open position
(parallel to the floor), and lift the door arm to the
trolley. The arm should touch the trolley just in
back of the door arm connector hole. Refer to the
fully open trolley/door arm positions in the
illustration. If the arm does not extend far enough,
adjust the limit further. One full turn equals 2" of
trolley travel.
Closed Door Adjustment:
Decrease DOWN limit
• Turn the DOWN limit adjustment screw clockwise 5
complete turns.
• Press the Door Control push bar. The trolley will
travel to the fully closed position.
• Manually close the door and lift the door arm to the
trolley. The arm should touch the trolley just ahead
of the door arm connector hole. Refer to the fully
closed trolley/door arm positions in the illustration. If
the arm is behind the connector hole, adjust the limit
further. One full turn equals 2" of trolley travel.
Connect the door arm to the trolley.
• Close the door and join the curved arm to the connector hole in the trolley with the remaining clevis pin. It may be
necessary to lift the door slightly to make the connection.
• Secure with a ring fastener.
• Run the opener through a complete travel cycle. If the door has a slight "backward" slant in full open position as
shown in the illustration, decrease the UP limit until the door is parallel to the floor.
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