| 摘要 |
A felt turning roll for use in the dryer section of a papermaking machine has a stationary shaft extending outwardly from at least one end of a perforated roll shell. The stationary shaft extends inwardly from the end of the roll for only a short distance which is substantially less than half the length of the face width of the roll. The stationary shaft is bored to permit a source of sub-atmospheric air pressure to be applied to its exterior portion. The inner portion of the shaft has a valve, a seal near its inner end between it and the roll shell, and openings to permit the exposure of sub-atmospheric air pressure within the roll shell on either side of the seal. The use of short stationary shafts eliminates the center shaft which otherwise would extend for the length of the roll. The roll therefore has a higher first natural frequency, and the use of the seal between the bored shaft and the interior wall of the roll shell permits the roll to apply a strong vacuum pressure beneath an annular area of the roll face near at least one end of the roll to facilitate threading of the papermaking machine during the start-up procedure.
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