Overhead Wire

(also a trolley wire), a flexible wire of a contact system that provides a sliding contact for a moving current collector. Such a wire is solid, with two lateral, longitudinal grooves in its upper part that are gripped by the suspension fittings. Overhead wires usually have a circular cross section; less frequently an oval cross section that narrows vertically is used. The wires are made of copper, sometimes with strengthening additives. To reduce wear of the contact surface, bimetallic over-head wires (copper or aluminum wires with steel inserts) are also used.