Patent ID: 7240538

Claim:
An apparatus, comprising: a generally cylindrical main body having a bore therethrough that defines first and second open ends, the bore including a central axis; first and second end plates fixed to the main body for closing the first and second open ends, the first end plate including a vent port and a pressure port that open into the bore radially distal from the central axis, the second end plate including a vent port and a pressure port; an alignment disc disposed in the bore and fixed atop the second end plate, the alignment disc including a vent port and a pressure port that open into the bore radially proximal the central axis, the vent port and the pressure port of the alignment disc being in fluid communication with the vent port and the pressure port, respectively, of the second end plate; and a movable sealing cap disposed in an opening in the first plate and movable along the central axis of the bore.