| 摘要 |
A cylinder (10) contains a pneumatically actuable piston (20) through which there runs a hollow piston rod (22) which is coupled to the piston (20) and in which the sensor (4) is arranged in a removable manner. The piston rod (22) extends through both end walls (12,16) of the cylinder (10) and has a head piece (26) which, in the retracted rest position of the piston rod (22), is arranged in a sealing manner in a head part (14) of the cylinder (10). In the region of a measuring head (34) of the sensor (4), the piston rod (22) contains at least one lateral inlet opening (30). To avoid unintended extension of the piston rod when no sensor (4) has been inserted, the piston rod (22) is provided, on that side of the piston (20) which faces away from the head piece (26), with at least one passage opening (46), through which the compressed air can escape when no sensor (4) has been inserted. With a sensor inserted, the openings (46) through which the compressed air escapes are sealed off leaktightly against the medium. <IMAGE>
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