Bearing & Wheel Scanners

Harmon

The original Harmon scanner. More information is needed on these.



Photos

Union Pacific

Servo 8909

Precursor to the well-known ACS scanner, the 8909 scanner was common to pre-talker detectors. Sites later upgraded to Servo System 9000s often kept these older scanners, with some remaining in active mainline service into the early 2000s. They could also be found in use with other manufacturers' detectors, such as Harmon.



Photos

Canadian Pacific Railway

Servo/GE Transportation/Progress Rail ACS-I/ACS-II

The ACS (Advanced Concept Scanner) is the most common type of scanner found on today's railroads. It replaced the 8909 scanner in the 1990s, and remains relatively unchanged in appearance today, even as it changed ownership from Servo to Harmon to GE Transportation & finally to Progress Rail. Older examples had the Servo logo cast into the housing; contemporary units are unbranded.

The ACS scanners were used on Servo 9000, Harmon Cyberscan 2000, and GE/Progress Rail MicroHBD detectors. Additionally, they were used on Devtronics CMA02 and Harmon Model 75 detectors (from the days before Harmon owned either Devtronics or Servo).

The current iteration of this line is the ACS II scanner. We have not been able to definitively identify the difference(s) between the ACS I and ACS II scanners, but will update this section when we do.



Photos

Nick Wilson



Photos

Nick Wilson

Servo/GE Transportation/Progress Rail MicroHWD

This ballast-mounted hot wheel detector is often used by Canadian railroads. Originally designed to look at a 30° angle to the passing train, they were later modified to look at a straight-on 90° angle.



Photos

Spencer Harman

Servo/GE Transportation/Progress Rail MicroScanIR

An alternative to the ballast-mounted MicroHWD is the MicroScanIR. Both devices scan for hot wheels, however the MicroScanIR is mounted directly to the rail in the same manner as the bearing scanners (except that the MicroScanIR is mounted at a 90° angle).



Photos

Nick Wilson

STC Type 1

Southern Technologies' first bearing scanners from the days of the Sentry 2058. There are two distinct version of the STC Type 1 bearing scanner: the larger scanner that reads the inside of the axle right next to the wheel bearing, and the smaller scanner that reads the end of the axle. The smaller variant is common to Norfolk Southern, and uses lesser temperatures to trigger alarms since heat dissipates further away from the bearing.



Photos

Bearing Scanner
Nick Wilson



End-of-Axle Scanner
Spencer Harman

STC Type 2 (Model 2100)

Southern Technologies' next generation scanners, which came out with later production Sentry units and lasted into the SmartScan NG era. Sites upgraded to the SmartScan NG² often retain the older Type 2 scanners.

Bearing Scanner
Nick Wilson

Wheel Scanner
Southern Technologies

STC Type 3 (Model 2500)

Southern Technologies' latest iteration of scanner, often seen packaged with later SmartScan NG units and their new SmartScan NG² model.

Bearing Scanner
Nick Wilson

Wheel Scanner
Nick Wilson