| 摘要 |
The rotary shaft of a vacuum and pressure pump is provided with an annular flat shoulder located between sections of different diameters. A stationary cylinder contains the shaft, semi-solid packing material, and the cylindrical part of a spring-loaded gland which is also stationary. The cylindrical part of such gland presses the packing material at its inner annular end toward the flat shoulder on the rotary shaft to form a superior vacuum seal. The shoulder on the shaft is simply formed either by a machining operation, or by welding a collar on the shaft.
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