Harmon Industries has a long history with the railroad industry, producing a variety of electronic systems including wayside signal systems, cab signal systems, crossing gates, crossing predictors, train control systems, two way radio systems, and of course, defect detectors.

Harmon Electronics was founded by Bob Harmon in 1946 to produce electronics & radio systems for railroads. One of Harmon's first innovations involved utilizing railroads' telephone circuits to communicate read-outs from hotbox detectors to a dispatch office where the train dispatcher could disseminate the results via radio. 1958 saw a contract signed with the Southern Railway for hotbox detector equipment, securing Harmon's future & allowing them to purchase permanent manufacturing facilities.

In 1981, Harmon Electronics purchased a line of defect detectors from General Electric, units that Harmon's West Coast operation had begun selling in the 1970s.

In 1987, Harmon Industries was founded as a holding company for Harmon Electronics and other subsidiaries. Additionally, subsidiary Consolidated Asset Management Company (CAMCO) was founded as a warehousing service for railroads, stocking signaling equipment that could be shipped to railroads on demand. Defect detectors purchased through this subsidiary were often branded as CAMCO, although they are Harmon models.

In 1994, Harmon Industries purchased Servo Corporation's Transportation Division, which consisted of Servo's line of hotbox detectors. Servo was integrated with Harmon Industries subsidiary Electro Pneumatic Corporation, although official literature from this era often lists Servo as its own division of Harmon.

In 1996, Harmon Electronics, CAMCO, and Electro Pneumatic Corporation were merged into Harmon Industries.

In 1997, Harmon Industries acquired Devtronics Inc., further expanding their market share & knowledge base.

In 2000, Harmon Industries was purchased by GE Harris Railway Electronics.

Model 24 (WCO-24)¹
An early hot bearing-capable model. More information is needed.

Model 32 (WCO-32)¹
The Model 32 utilized Harmon WCO-33 bearing scanners. The processor of the system was known as the WCO-34.

Cyberscan 2000
Introduced in 1994 by Harmon subsidiary Servo, the Cyberscan 2000 was the first Harmon unit to utilize a different voice than its predecessors. Production of the Cyberscan 2000 ended in December 2005.

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Model 46 (WCO-46)¹
A very simplistic model with minimal inputs - it did not even support transducers for axle counts.

Mini Talker-2
A much more capable unit than the Model 46, the Mini Talker-2 supported transducers for axle counts, among numerous other features.

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Model 75 (WCO-75)¹
The Model 75 was an overlay system for existing hot bearing-capable sites that added talker functionality. This system used the same WCO-34 processor as the WCO-32 system, with the addition of a Servo Overlay Interface Board in order to work with the Servo scanners.