Locking (Safe connection)

Mechanical or electromechanical, electrical or electronic constrained link, with safety features, by which devices of correlated and usually concurrent devices are physically allowed or not allowed to activate, in order to ensure a safe movement of trains. One of the fundamental safety connections is the constraint that exists between the maneuvering devices of a signal and the switch or any other devices. The connection is such as to ensure that for the signal free arrangement, all the devices related to it are constrained in the required position; the release of these devices can take place after having checked the impeded position of the signal, which indicates that the train has already benefited from the free-form aspect of the mentioned signal