[DonRotolo]

Moving forward is not difficult, but moving up is the trick.

The image below shows how to make a 'triple' lift using one cable. All the attachments are pulleys except the one on the left-most (top) element. Pull the cable, the arms go up.

To move the whole assembly forward, use a pnuematic or hydraulic piston to slide it out, with a mechanism like you would see in a desk drawer.