In a typical container port yard, containers are moved and stacked by rubber-tired gantry cranes (RTGs). This type of crane is not rail-guided, which means it can move from one aisle to another. With a “hybrid” electrified E-RTG, a battery array supplies the energy required for any movement of the RTG.
A small gen-set charges the battery array when necessary. With a “Full-E-RTG” system, the crane is normally connected to the power grid via a conductor rail system or motor-driven cable reel while it is operating in the aisle. For movements outside the container lane, the RTG employs its battery system.