In an electric rail system, power is supplied by overhead lines that run along the entire length of railway tracks, amassing large carbon footprints. The power is transferred to the train by means of a pantograph, which is a current collector mounted on top of the locomotive.  ATD provides a mechanism for automatic tensioning of overhead equipment (OHE) lines to ensure smooth collection of current by the moving pantograph. Tensioning is needed on the contact lines due to variation in their lengths. Contact lines are primarily made from copper-based alloys, prone to expansion and contraction due to variation in atmospheric temperatures.  The absence of tensioning causes overhead lines to sag or tighten, leading to pantograph entanglement or snapping of OHE lines.  

The indigenous spring ATD is light in weight and caters to load requirements upto 30 KN.