| 摘要 |
<p>A feeding device for web material, having a pneumatic actuator assembly (B) incorporating a three-way pneumatically piloted control valve (8) which controls the communication between the pneumatic actuator assembly (B) and, respectively, a source of air under pressure (A) and a discharge port (C). The control valve (8) comprises a floating obturator (30) defining a first and a second face seal surfaces (31, 32) for airtight closure of the feed line (A) in presence of the piloting pressure, and of the discharge line (C) in the absence of the piloting pressure, respectively. <IMAGE></p> |
