| 摘要 |
PCT No. PCT/GB85/00394 Sec. 371 Date May 2, 1986 Sec. 102(e) Date May 2, 1986 PCT Filed Sep. 4, 1985 PCT Pub. No. WO86/01493 PCT Pub. Date Mar. 13, 1986.A pneumatic valve mechanism, especially for controlling the movement of paper, comprises a mouthpiece (47) which defines an air intake (58), a bellows (10) coupled to the mouthpiece, a passage (42, 44) connecting the interior of the bellows to a pump so that when the bellows is not fully retracted suction is created at the air intake (58) and a seal (50) between the mouthpiece and a valve body (14) which is effective when the bellows is fully retracted, following closure of the air intake by a sheet of paper (60), to seal the air intake from the suction pump. Venting air can enter the mouthpiece in the retracted position of the bellows, to permit the sheet to drop off the intake, but without breaking the seal (50), whereby the bellows is maintained in its retracted position. The bellows (10) will only extend again to seek the next sheet when the effect created by the suction pump is interrupted, as by breaking the seal (50) by energizing a solenoid (64) and displacing a mechanical linkage (62,54).
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