Pneumatic sealing apparatus

An apparatus for controlling the elastic deformation of the open end of a cylindrical sealing body between a closed position to momentarily enclose and seal around the end of a cylindrical article to be pneumatically tested and an enlarged open position, the sealing body mounted on a support member and attached to a holding member at the other end from the support member so that relative axial movement between the support member and holding member causes the opening and closing, the apparatus comprising:

• means for carrying and moving said sealing body, said support member and said holding member along a travel path which is generally perpendicular to the axis of said sealing body, one of said members being axially movable relative to said carrying means and the other member being fixed thereon;
• fixed control means for controlling relative movement between said support member and holding member, said control means being arranged along a control path generally paralleling said travel path;
• a first magnetic device carried by the movable one of said members and extending toward said control means;
• and
• said control means comprising second and third magnetic devices having magnetic properties differing from each other arranged along segments of said control path such that said first magnetic device is differently attracted and repelled thereby, causing axial movement of said first device and the movable member and concurrent opening and closing of said sealing body, at least one of said first, second and third magnetic devices being a permanent magnet.