[JasonB]

I like Leo's suggestion, because as has been said, folding tables can be complex and expensive.

Something like this might work though...

Here are your three pieces all set up.

   

The end piece has two battens screwed to the underside of the table top, with two pieces of dowel glued in.

   

The middle piece also has two battens which slide inside the battens on the first piece.

   

Each leaf has holes in the underside which the dowels slot into, so you angle the second piece upwards...

   

... slide together, and lower to locate the dowels into the holes. The dowels would need to be rounded off at the ends for this to work.

   

Repeat for the third piece...

   

... and build your track.

   

The second and third pieces would ony need two legs as each would be supported by the piece before.