LiftMaster 3255 3255 Manual - Page 22

ALL ONE-PIECE DOORS 1. Assemble the door arm, Figure 4: • 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 the 5/16"x1-1/4" clevis pin. • Secure with a ring fastener. 2. Adjustment procedures, Figure 5: • 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 23. Follow adjustment procedures below. • Open door adjustment: decrease UP travel limit - Turn the UP limit adjustment screw counter-clockwise 4 turns. - Press the Door Control push button. 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" (5 cm) of trolley travel. • Closed door adjustment: decrease DOWN travel limit - Turn the DOWN limit adjustment screw clockwise 4 complete turns. Door Bracket Ring Fastener Clevis Pin 5/16"x1-1/4" Figure 4 Straight Arm Bolts 5/16"-18x7/8 Lock Washers 5/16" Nuts 5/16"-18 Curved Door Arm - Press the Door Control push button. 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" (5 cm) of trolley travel. 3. 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. NOTE: 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. Figure 5 Inner Trolley Outer Trolley Door Arm Door Arm Connector Hole Emergency Release Handle Closed Door Inner Trolley Outer Trolley Correct Angle Door Arm Open Door Door with Backward Slant (Incorrect) 22