Craftsman 139.18451DM Manuel D'instructions page 27

ADJUSTMENT STEP 1
Adjust the UP and DOWN Travel Limits
Limit adjustment settings regulate the points at which the door
will stop when moving up or down.
To operate the opener, press the Door Control push bar. Run the
opener through a complete travel cycle.
1. Does the door open and close completely?
2. Does the door stay closed and not reverse unintentionally when
fully closed?
If your door passes both of these tests, no limit adjustments are
necessary unless the reversing test fails (Adjustment Step 3,
page 29).
Adjustment procedures are outlined below. Read the procedures
carefully before proceeding to Adjustment Step 2. Use a
screwdriver to make limit adjustments. Run the opener through a
complete travel cycle after each adjustment.
NOTE: Repeated operation of the opener during adjustment
procedures may cause the motor to overheat and shut off. Simply
wait 15 minutes and try again.
NOTE: If anything interferes with the door's upward travel, it
will stop. If anything interferes with the door's downward travel
(including binding or unbalanced doors), it will reverse.
HOW AND WHEN TO ADJUST THE LIMITS
• If the door does not open completely but opens at least
5 feet (1.5 m):
Increase up travel. Turn the UP limit adjustment screw
clockwise. One turn equals 2" (5 cm) of travel.
NOTE: To prevent the trolley from hitting the cover protection
bolt, keep a minimum distance of 2 - 4" (5 cm - 10 cm) between
the trolley and the bolt.
• If door does not open at least 5 feet (1.5 m):
Adjust the UP (open) force as explained in Adjustment Step 2.
• If the door does not close completely:
Increase down travel. Turn the down limit adjustment screw
counter-clockwise. One turn equals 2" (5 cm) of travel.
If door still won't close completely and the trolley bumps into
the pulley bracket (page 4), try lengthening the door arm
(page 25) and decreasing the down limit.
• If the opener reverses in fully closed position:
Decrease down travel. Turn the down limit adjustment screw
clockwise. One turn equals 2" (5 cm) of travel.
• If the door reverses when closing and there is no visible
interference to travel cycle:
If the opener lights are fl ashing, the Safety Reversing Sensors
are either not installed, misaligned, or obstructed. See
Troubleshooting, page 22.
Test the door for binding: Pull the emergency release handle.
Manually open and close the door. If the door is binding or
unbalanced, call for a trained door systems technician. If the
door is balanced and not binding, adjust the DOWN (close)
force. See Adjustment Step 2.
Without a properly installed safety reversal system, persons
(particularly small children) could be SERIOUSLY INJURED or
KILLED by a closing garage door.
• Incorrect adjustment of garage door travel limits will
interfere with proper operation of safety reversal system.
• If one control (force or travel limits) is adjusted, the other
control may also need adjustment.
• After ANY adjustments are made, the safety reversal system
MUST be tested. Door MUST reverse on contact with 1-1/2"
high (3.8 cm) object (or 2x4 laid fl at) on fl oor.
To prevent damage to vehicles, be sure fully open door
provides adequate clearance.
2-4"
(5 cm-
10 cm)
27
Left Side Panel Limit Adjustment
Screws
ADJUSTMENT LABEL