JOINT DEVICE OF A POWER RAIL

The present invention relates to an expansion and absorption apparatus of a power supply rail capable of absorbing expansion of a power supply rail due to a temperature. Moreover, the expansion and absorption apparatus is mounted on a unit rail comprising: a conductive contact part (111) in contact with a current collecting part of a railway vehicle; and a body part (112) wherein the contact part (111) is fitted and assembled, and installed along a track of the railway vehicle in order to connect unit rails (110, 120) adjacent to each other. The expansion and absorption apparatus comprises: a first sliding member (130) and a second sliding member (140) located in each end of unit rails (110, 120) adjacent to each other while having the same width with the contact part, fixed to the body part (112) of the corresponding unit rail (110), and to be slid in a longitudinal direction; a fastening member (150) to fasten the first sliding member (130) to the second sliding member (140); and a connector cable (160) to connect the unit rails (110, 120) adjacent to each other. The first sliding member (130) to the second sliding member (140) include at least two sliding plates (131, 132, 141, 142) prepared at a distance away from each other. Each sliding plate ((131, 132, 141, 142) of the first sliding member (130) to the second sliding member (140) is alternately arranged with each other, and thereby surfaces thereof are in contact with each other.