self-dumping

So great are these detailed difficulties that many mines are sending cars to the surface in cages when they should be equipped for bin-loading and self-dumping skips.

Principles of Mining Valuation, Organization and Administration Herbert Hoover 1919

_Third_, three reasons are rapidly making the self-dumping skip the almost universal shaft-vehicle, instead of the old cage for cars.

Principles of Mining Valuation, Organization and Administration Herbert Hoover 1919