Freight trains in cold weather districts are equipped with a tail sign lamp with built-in storage batteries and an anti-freezing heater to ensure visibility from behind. As existing tail sign lamps can be used continuously for only 30 hours at -20ºC, an increase in the number of long-distance freight cars has created a demand for the development of a new tail sign lamp to save on maintenance work and ensure uninterrupted use for longer periods. To this end, the RTRI has developed a tail sign lamp that is compact, lightweight and easy to maintain, offering a continuous service period of 96 hours at -20ºC.
The new tail sign lamp, fitted with lithium ion batteries, ultra-high luminance LEDs and a DC-DC converter (Fig. 1) provides a reduction of 30% in weight and 50mm in depth (Fig. 2) over conventional models, and can be continuously used for 120 hours at -20ºC. The RTRI has confirmed through field tests on main line (Fig.3) that there are no problems with the lamp, even when used for periods of more than 100 hours, meaning that freight trains can make a round trip between Hokkaido and Kyushu without tail sign lamp replacement. The RTRI has halved the battery's charge time, eliminated refreshing discharge operation and battery fluid refilling, and made it possible to place the lamp on its side (Table 1).
Although the unit price is about twice that of the existing version, it is thought that the overall cost of the tail sign lamp rotation system will decrease. This is because the continuous service time of the lamp is tripled, the number of lamps in stock will decrease significantly, manpower and costs for lamp replacement work will be cut, and the dwell time of trains will become shorter..