Chessie System Servo System 9000

Perhaps the best known Conrail defect detector is the Servo 9000 System model, which began appearing in the mid 1980s. While generally employed as a Hotbox Detector, Dragging Equipment Detector, & Hot Wheel Detector (HWD), they were sometimes as a High Car Detector (HCD) as well. As originally configured, they did not provide a speed or axle count, did not end the transmission with 'over,' and had a much quicker pace. Later, a new CPU was introduced that allowed for the addition of axle count and the word 'over' at the end of the transmission; the pace of the transmission was also slowed down. Around 1995, train speed was also added to the transmissions. Many of these lasted well into the mid 2010s on both CSX & NS, with CSX dropping the 'Conrail' introduction around 2007 while NS reprogrammed theirs to mimic their other detectors within a few years of the Conrail split-up. In 2016, CSX made a big push to eradicate these detectors and standardize much of the former Conrail territory with Progress Rail MicroHBD units; by this late date, many of the original Servos were having issues with false positives and 'Detector Not Working' messages.

-Information courtesy of Nick Wilson from defectdetector.net