Complex sentence: Turnplates were initially made of two or four piece of wood which replicated the track running through them, and circular in form they were the diameter of the wagons used on that wagonway, and swung around a central pivot.
Split into simpler sentences: Turnplates were initially made of two or four piece of wood which replicated the track running through them, and circular in form. They were the diameter of the wagons used on that wagonway, and swung around a central pivot.