| 摘要 |
The invention relates to a device for sealing in the zone of contact between the mouths of alternately charging and discharging delivery cylinders of a concrete pump and a swinging pipe that is alternately movable to alignment in front of the cylinder that is discharging at the time. It comprises an annular seal body so supported at the mouth zone of the delivery cylinder as to be slidable between a sealing position projecting into the rear end portion of the swinging pipe and a withdrawn releasing position in which it is spaced from the swinging pipe so as not to interfere with its swinging. The seal body is maintained in its withdrawn position whenever the swinging pipe is moving, thus substantially avoiding abrasion.
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