LiftMaster SW420 SW420 S3 BOARD Manual - Page 23

Limit Switch Adjustments 23 12 Fine tune both the open and close limit switch settings by using the OPEN, CLOSE and STOP buttons to move the gate and by rotating the limit collars slightly to allow more or less gate travel. Rotating cam away from the limit switch increases gate travel. Rotating cam towards the switch allows less gate travel. CAUTION Always turn off power before placing hands or tools in operator or near drive shaft and control arm. The close limit switch should stop the gate at a point where the elbow of the control arm just passes the position when the (2) arm pieces are in a straight line (180 degrees). With the control arm past the 180-degree position, the gate is effectively locked against any attempts to push it open from the outside. Refer to Figure 10. The extra holes in the control arm extension may be used to aid in attaining the final desired close position of the gate and arm. Doc 01-G0610 Rev A