Apparatus for gripping workpieces using a vacuum includes a plurality of throat bores in a support block, each bore having a constricted portion of its length of a diameter such that the air flow permitted through all of the bores together is less than the pumping capacity of a vacuum pump that draws...http://www.google.ca/patents/US4787662?utm_source=gb-gplus-sharePatent US4787662 - Vacuum driven gripping tool
