![]() Now railroads are required to use “two-way” equipment. ![]() Early units simply transmitted data to the cab. If there is a loss of radio continuity between the ETD and the cab, this will be displayed.įlorida East Coast pioneered ETD use in 1969, and most other railroads followed suit by the mid-1980’s. Information on the marker light (on or off) and batteries (how much charge is left) is also included in ETD radio messages. Radio transmissions from the unit tell the engine cab if the rear end is stopped or moving forward or backward. The engineer can thus monitor the integrity of the train line as he sets and releases the brakes.ĮTD’s are also equipped with sensors that determine motion of the rear end. This information is transmitted by radio to the engine cab, which must have equipment to receive, decode, and display the data. This way, the ETD gathers data on the brakeline pressure, one of the most crucial measurements on any train. A sensor extends down from the ETD unit (which, depending on the design, can be mounted on the knuckle or the side of the coupler) and attaches to the end of the air hose. (Many streetlights and yard lights work this way.) Reflective material, sometimes striped, on the exterior of the ETD is meant to catch the headlight beam of an approaching locomotive, so the unit still provides warning even if the ETD light has failed.Īnother important ETD job is the monitoring of the brake-pipe pressure. ![]() Powered by rechargeable batteries, the marker is controlled by a photoelectric cell which turns the flasher on when ambient light levels become low. Perhaps their most visible element is the flashing marker light. Most ETD’s are of the “smart” variety, so called because of their ability to do a number of tasks. The caboose’s other functions are now performed by end-of-train telemetry, best represented by the end-of-train device (ETD), the small metal box with a flashing light on the rear coupler of the last car. Defect observation has been taken over by trackside detectors, the conductor now does his paperwork in the engine cab, and many main-line switches are thrown by remote control (though many others are still manual). Cabooses also carried marker lights to warn following trains.īut the caboose has yielded to other technology. The distinctive little cars housed crew members who would observe the cars ahead for defects, process the train’s paperwork, operate track switches, monitor the air-brake system to see if it was functioning throughout the train, observe if the train was moving or stopped as intended by the engineer, and apply the brakes in an emergency. Not so long ago, train-watchers almost everywhere could count on a final point of interest at the end of each freight train: a caboose.
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