Limit switch, part 170004-03, for the automatic wiper on Hanovia medium-pressure ultraviolet disinfection systems. The switch tells the controller that the wiper has reached the end of its travel, which is how the drive is reversed and how a stalled wiper is detected. A failed limit switch typically shows as a wiper that runs continuously, will not reverse, or reports a drive fault while the motor itself is sound — worth checking before condemning the motor. Reference number 2278-0410.