Multiple Track Overlap

Mk1 equipment on multiple tracks uses four masts for both fixed and automatic tensioned equipment. In areas where speed is slow fixed tensioned overlap can be found without the two middle masts. The outer two are heavy framed portal mast with meduim load mast in the middle. Automatic tensioned overlap has the balance weights housed in the uprights of the mast. There is a system of pulleys and wires within the mast for the tensioning. The central two mast carry the out of running and contact wire registration arms, if the overlap has isolators these are carried on these mast. Like twin track any booster transformers are on their own mast.

Mk3 headspan requires six masts, the outer two support the balance weights for the inner tracks. The intermediate pair has the balance weights for the outer tracks and carry the out of running wire for the inner tracks. The centre mast have the contact wire and out of running registrations. Isolating switches, booster transformers etc are to be found on the central pair of masts.

Where an overlap is on curved multiple track the registration has to be on the outside of the curve as with twin track.