Electric locomotives are a type of traction equipment for rail vehicle transport, powered by driving the wheels with traction motors. They utilize the friction between the wheels and the rail surface to move along the tracks. This mode of operation is limited by both the power of the traction motor (or internal combustion engine) and the friction between the wheels and the rail surface. The transport capability of the locomotive is restricted by the gradient it can travel, with the general gradient of the transport track being 3‰, and local gradients not exceeding 30‰. They are categorized structurally into overhead wire locomotives and battery-powered locomotives.

Cable-Driven Electric Trolley

The process of the overhead wire electric locomotive: The high-voltage AC power is stepped down and rectified at the traction converter, with the positive terminal connected to the overhead wire and the negative terminal to the rail. The pantograph on the locomotive contacts the overhead wire, introducing the current into the carriage, then through the air automatic switch, controller, and resistor box into the traction motor, driving the motor to operate. The motor drives the wheels through a transmission device, thus propelling the train forward. The current流出 from the motor returns to the converter through the rail.