A device for the maintenance of an overhead line system of a track has a handling device and a displacement device. The displacement device serves to displace the handling device between a transport position and a working position. In the working position, the handling device reaches the overhead line system and is able to perform maintenance work by way of a tool. At least one sensor serves for controlling and/or monitoring the handling device. The device thus enables a simple, efficient and safe maintenance of the overhead line system.