Abstract: An apparatus for exchanging articles with an article holder includes a vertical mast having a vertical mast axis and a shuttle ring assembly. The shuttle ring assembly has a central aperture surrounding the mast and is coupled to the mast to allow the shuttle ring assembly to be translated vertically along the mast through multiple heights between a lower height and an upper height. The shuttle ring assembly includes a rotary member coupled to the mast to be rotated through multiple orientations about the mast axis. The rotary member includes multiple article-holding fixtures, angularly spaced from each other about the mast axis. The multiple orientations include a respective exchange orientation for each of the article-holding fixtures. The rotary member can be positioned in any one of the exchange orientations so that a selected one of the article-holding fixtures is in an associated exchange position.

Abstract: A dual piston alternately reciprocating pumping apparatus utilizing, in part, a pressure based precompression stroke to provide product at a substantially uniform discharge pressure. In operation, a first feed piston is advanced through a first feed cylinder to discharge product therefrom, during which time a second feed piston is retracting within a second feed cylinder to obtain a product charge therein. The second feed piston reaches bottom dead center and thereafter advances through the second feed cylinder on a precompression stroke, during which no product is discharged from the second feed cylinder. After a predetermined pressure related to that within the second feed cylinder is detected, further advancement of the second feed piston is terminated and is not reactivated until the first feed piston nears top dead center. Therefore, a product having a substantially uniform discharge pressure is provided.