Mueller Roll-Up Door C250 - Manual (Page 13)

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STEP 16: ADJUST SPRING TENSION
DOOR MUST BE IN THE FULLY OPENED POSITION TO ADJUST SPRINGS.
A Open door fully with the bottom bar resting against
the head stops.
B At dual tensioner end, place ½ inch ratchet into tensioning
hub and hold the ratchet firmly. Have someone else loosen
the square, red headed 3/8 inch set screws on the dual
tensioner and support bracket.
C To increase spring tension, pull down on ratchet ¼ turn.
The dual tensioner will automatically grip the axle and help
hold the new tension setting. Have someone else tighten all
square, red headed 3/8 inch set screws in dual tensioner and
axle support bracket at both ends of the door.
D To decrease spring tension, momentarily pull down on
ratchet and then lift the spring roll pin on the dual tensioner’s
knurled wheel. Gently let up on the ratchet, allowing the
axle to rotate ¼ turn to reduce the tension. While holding
the new tension, release the dual tensioner’s spring roll pin.
The dual tensioner will now grip the axle and help hold the
new tension setting. Have someone else tighten all square,
red headed 3/8 inch set screws in dual tensioner and axle
support bracket at both ends of the door.
E Verify that all square, red headed 3/8 inch set screws in dual
tensioner and axle support bracket at both ends of door are
tightened prior to checking door operation.
F Repeat steps 16A through 16E as necessary.
LOSS OF SPRING TENSION WILL CAUSE
DOOR CURTAIN TO DROP RAPIDLY.
LOSS OF SPRING TENSION WILL CAUSE
DOOR CURTAIN TO DROP RAPIDLY.