Patent for improvements in self-dumping cage for hoisting coal or other minerals by first provide a simple and easily-controlled dumping mechanism which can be set at bottom of shaft; second, to secure a positive action of the dumping mechanism and reduce the shock and strain commonly incident to the operation of self-dumping cages; third, to provide a firmer and more easily operated dog for holding car on cage-platform. (Lines 15-22) Illustration is included.