| 摘要 |
A strap sealer has a dual action piston. A seal forming assembly is operably connected to the piston. The sealer includes a housing that defines a cylinder and has a penetration therein. A piston is disposed in the cylinder for reciprocating movement. The piston defines upper and lower pressure regions of the cylinder. The sealer includes a compressed air inlet, first and second flow paths between the inlet and the upper and lower pressure regions and a valve assembly for providing flow communication between the inlet to supply air to and exhaust air from the upper and lower pressure regions. A ram is mounted to t he piston for reciprocating movement therewith. The ram traverses through the housing penetration. The ram has first and second cross-sectional areas that are different from each other. As the piston reciprocates, the ram traverses through the housing penetration. When the first cross-sectional area resides at the housing penetration a seal is formed and when the second cross-sectional are a passes through the housing penetration a vent path is provided from the lowe r pressure region outwardly to vent air from the lower pressure region.</SDOAB >
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