Rail mounted crane for timber building construction - has truck travelling on main rail with gantry and crab movable onto cross rails

摘要

The rail mounted crane has a main rail and pairs of other rails at right angles to it, each beginning at the same distance from the main one. A truck travels along the main rail, and carries two rail sections at the same gauge as that of the pairs of cross rails. When the truck is in the appropriate position, these extend the cross rails to the centre line of the truck. A gantry travels with the truck, and along the rail sections and cross rails, and has a crab with a hoist winch.