Turned leg leaf oak dining table with two leaves. American late 19th/20th century. Together with 16" leaves. 
Table fitted with a mechanism called a screw expander. The table is fitted with a mechanism that consists of a long threaded screw that turns in a long tube nut. 
Both pieces are fitted to either end of a dining room table and when turned by removable cvrank or winder from one side, the screw and the nut work against eachother and the table is opened. 
Dimensions: 31 X 40 d X 64