Product design and operation overview • The Gantry post signal head equipment, mounted on a signal head platform (moveable carriage) is connected, via a chain and sprocket mechanism, to a moveable counter-balance weight carriage. • The signal head carriage is fitted with a wheel-block (roller) assemblies that run in guide rail channels formed by the post structure. • The chain and sprocket mechanism and counter-balance weights ensure that minimum effort is required to raise or lower the signal head into position. • The chain and sprocket mechanism and counter-balance carriage are located inside the post which has a lockable door. The door allows access to the counter-balance mechanism and, when fully closed and locked, ensures the signal head remains in its fully lowered Operating Position. • Two dampers, located at the top of the post, one mounted inside the post parallel to raise/lower hand-wheel, and the other just below the post end cap, cushion the signal head from a hard impact when it is raised or lowered to the full extent of its travel.