I finally dissected one of those modern aluminum cable connectors. A simple thing, basically nothing more than a Chinese finger trap, with the big difference being there is no way to release the cable once it is inserted. The higher the load pull, the tighter the clamp holds.

A red plastic insert located at each tip guides the end of the cable into a small aluminum socket that allows smooth passage of the cut end of the cable through the aluminum two piece clamp, through the centre of a spring to the divider . Insertion is complete when the cable end reaches the captive plastic divider located half way from either end. The spring holds the clamp towards the outer, smaller end of the connector, into which the clamp will be pulled as the tension is increased. The higher the tension, the tighter the grip.