Pneumatic pop-up units for material handling equipment

摘要

Pneumatic pop-up unit for material handling equipment. In a preferred embodiment, the unit comprises a stamped metal housing having a circular side wall, a bottom wall, a circumferential flange extending radially outwardly from the top of the side wall, and an open top. The unit also comprises a stamped metal cap, the cap comprising an annular top wall, an inner side wall extending into the housing through its open top, and an outer side wall bent down across the outside edge of the flange and then radially inwardly against the bottom surface of the flange. The unit further comprises a two-piece stamped metal piston slidably mounted within the housing, the piston comprising a top piece and a bottom piece. The top piece is a generally cylindrical, hollow member and includes a circular side wall, a peripheral flange extending radially outwardly from the bottom of the side wall, an open bottom, and an open top. The bottom piece is shaped to include an open top, a circular upper side wall, an annular shelf extending radially inwardly from the bottom of the upper side wall, a circular lower side wall extending downwardly from the inner diameter of the shelf, and a convoluted bottom wall that forms an upwardly-facing bowl-shaped central portion. The flange of the top piston piece is seated directly on top of the shelf of the bottom piston piece. The unit further comprises a stamped metal race disposed within the piston. The race, which includes a bowl-shaped portion, is seated on top of the bowl-shaped central portion of the convoluted bottom wall and is loosely secured to the top piston piece by a slip-fit. A plurality of ball bearings are dispersed in a monolayer within the race. A primary ball is seated directly on top of the bearings and is freely rotatable thereon. The top of the primary ball extends partially through the open top of the top piston piece. The unit further comprises a rubber seal snugly fitted around the bottom piston piece and a coiled spring for biasing the piston downwardly within the housing.