| 摘要 |
A pneumatic pop-up unit having an open-topped housing and a piston slidably received therein, the piston accommodating a contact element at least partially extending above the open top of the piston and a seal attached to the outside surface of the wall of the piston about the circumference thereof, configured and arranged to form a substantially air-tight seal with the inside surface of the side wall of the housing, wherein the bottom wall of the piston, and the seal form a sealed volume with the bottom wall and side wall of the housing, a cap attached to the open top of the housing, the cap having a flange and a central opening having a descending guide channel sized to slidably receive the outside surface of the side wall of the piston, wherein the cap is secured about its circumference to the side wall of the housing at the open end thereof by a single-seam crimped, rolled, coined, spun or swaged joint. Gas under pressure can be admitted to the sealed volume to elevate and suspend the piston such that the contact element is partially extended above the flange of the cap.
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