Pneumatic pop-up units for material handling equipment

A pneumatic pop-up unit comprising:

• (a) a housing having a bottom wall, a side wall extending upwardly from said bottom wall, a plurality of flanges extending outwardly from the top of said side wall, and an open top wherein said flanges are equidistantly separated by spaces;
• (b) a piston slidable within said housing between a lower position and an upper position, said piston having an upper opening;
• (c) a contact element seated within said piston and partially extending through the upper opening of the piston;
• (d) a cap positioned on top of said open top of said housing, said cap being shaped to include a top wall and a plurality of tabs extending downwardly and inwardly from the outer perimeter of said top wall, said top wall being provided with a central opening through which said contact element partially extends when said piston is in said upper position, at least one of said tabs and said flanges being provided with means for releasably securing said tabs to said flanges, said tabs being appropriately sized for insertion through said spaces between said flanges;
• (e) a spring for biasing said piston toward said lower position;
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• (f) a nipple mounted in said housing for use in admitting fluid under pressure to said housing to elevate said piston against the bias of said spring toward said upper position.

A pneumatic pop-up unit comprising:

• (a) a housing having a bottom wall, a side wall extending upwardly from said bottom wall, and an open top;
• (b) a multi-piece piston slidable within said housing between a lower position and an upper position, said multi-piece piston comprising a top piece shaped to include a generally cylindrical side wall, an open top and an open bottom, the top edges of said generally cylindrical side wall being curled inwardly;
• (c) a contact element seated within said multi-piece piston and partially extending through the open top of said top piece of said multi-piece piston, said contact element being retained within said multi-piece piston by the inwardly-curled top edges of said generally cylindrical side wall;
• (d) a cap positioned on top of said open top of said housing and secured to said housing, said cap having a central opening through which said contact element partially extends when said multi-piece piston is in said upper position;
• (e) a spring for biasing said multi-piece piston toward said lower position;
• and
• (f) a nipple mounted in said housing for use in admitting fluid under pressure to said housing to elevate said multi-piece piston against the bias of said spring toward said upper position.

A pneumatic pop-up unit comprising:

• (a) a housing having a bottom wall, a circular side wall extending upwardly from said bottom wall, a circumferential flange extending outwardly from the top of said circular side wall, and an open top;
• (b) a multi-piece piston slidable within said housing between a lower position and an upper position, said multi-piece piston comprising a top piece and a bottom piece, said top piece and said bottom piece jointly defining a piston chamber, said top piece being shaped to include a generally cylindrical side wall, a peripheral flange extending outwardly from the bottom of said generally cylindrical side wall, an open top and an open bottom, the top edges of said generally cylindrical side wall being curled inwardly, said bottom piece being shaped to include an open top, a circular upper side wall, an annular shelf extending radially inwardly a short distance from the bottom of said circular upper side wall, a circular lower side wall extending downwardly a short distance from the inner diameter of said shelf, and a bottom wall, said bottom wall being shaped to include a concave-up central portion, said circumferential flange of said top piece being seated on top of said shelf of said bottom piece;
• (c) a race disposed within said piston chamber, said race being shaped to include a bottom wall having a concave-up shape and a circular side wall extending upwardly from the outer periphery of said bottom wall, said bottom wall of said race being seated on said central portion of said bottom wall of said bottom piece of said multi-piece piston;
• (d) a plurality of ball bearings, said ball bearings being seated on said bottom wall of said race;
• (e) an omni-directional ball seated on said ball bearings and partially extending through the open top of said top piece of said multi-piece piston, said omni-directional ball being retained within said multi-piece piston by the inwardly-curled top edges of said generally cylindrical side wall;
• (f) a cap, said cap being shaped to include a top wall, an inner side wall and an outer side wall, said top wall having a central opening through which said omni-directional ball partially extends when said multi-piece piston is in said upper position, said inner side wall extending downwardly from the inner diameter of said top wall into said housing, said outer side wall extending downwardly from the outer diameter of said top wall, said outer side wall being bent around and under said circumferential flange of said housing to secure said cap to said housing;
• (g) a spring, for biasing said multi-piece piston toward said lower position, said spring having a lower end and an upper end, said lower end being seated on said peripheral flange of said top piece of said multi-piece piston, said upper end abutting the lower surface of said top wall of said cap;
• (h) a seal fitted around said circular lower side wall of said bottom piece of said multi-piece piston and engaging the inside surface of said circular side wall of said housing for creating an air-tight chamber between said multi-piece piston and said housing;
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• (i) a nipple mounted in said housing for use in admitting fluid under pressure to said housing to elevate said multi-piece piston against the bias or said spring toward said upper position.