Tower alignment system and mechanism that allows programmed changes to the alignment automatically

An alignment unit to control an irrigation system drive tower carrying a linear pipeline along a path, the alignment unit comprising:

• a housing affixed to the drive tower or the linear pipeline;
• an alignment sensor operable to measure a real-time alignment of the drive tower;
• an alignment controller in communication with the alignment sensor, the alignment controller operable to receive the real-time alignment of the drive tower and energize a drive unit based on a first range of real-time alignment values, the alignment controller including a cam coupled to the alignment sensor which rotates in response to changes in the real-time alignment, the cam including a control notch and a safety notch;
• a safety switch with a roller coupled to the cam such that when the roller does not contact the safety the drive unit is deenergized;
• an actuator in communication with the alignment controller, the actuator operable to reorient at least a portion of the alignment controller in relation to the alignment sensor;
• and a reorienting disc coupled to the alignment controller and the safety switch and rotated by the actuator, wherein rotation of the reorienting disc changes the orientation of the alignment controller and the safety switch.