The invention uses one or more scissor devices, or disks, or cogs such that the axial thermal expansion of a coupling member is amplified such that this amplified movement is used to automatically mitigate the sag of a suspended line; the same ambient temperature change that causes the line to sag concomitantly causes the coupling member to expand, so that sag mitigation is passive and automatic. The invention includes a device for automatically mitigating thermal expansion sag in suspended lines comprising a coupling member or actuator rod (140) that expands axially with increasing temperature and that is mounted between the proximal arms (110) of a reverse-scissor component (60), said reverse-scissor component having first arms (70) and second arms (80) and a hinge (90) and the arms having distal ends (100) longer than proximal ends (110). The distal arms are insulated by insulators (130). The reverse hinge acts such that when the proximal arms are moved apart, the distal arms are brought together. The distal arms of the reverse-scissor component are attached to a power line (120) such that when the distal arms are brought together, the slack in the power line is taken up automatically as ambient temperature increases.