| 摘要 |
A tubular all-rubber member has one end closed and an end through which air may be pumped into it. A tubular end portion of the member has a series of plug body portions alternating with a series of pairs of flexible inclined ribs that are thin at their outer ends and join a plug body portion at a thicker inner end portion. Between each pair of ribs lies a concave expandable ring that normally lies radially within the plug body. Each rib lies at about 10 DEG to its adjoining body portion so that it faces away from the concave ring, so that when the plug is installed into a sewer pipe, it is freely movable inside the pipe to a desired position and can then be pneumatically expanded so that the concave rings expand and grip the pipe wall surfaces and the thin angular ribs move to grip both the plug and the pipe.
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