Closure means for a cylindrical housing

Closure means for use in closing an open end face of a cylindrical housing, said cylindrical housing having an interior with a surface, said closure means comprising:

• an annular cap, said annular cap having a cylindrical inner surface, said cap having a cylindrical reception opening;
• two extensions projecting toward a longitudinal axis of the annular cap along the cylindrical inner surface of said cap, a groove-shaped reception area defined by the inner surface between said extensions, said inner surface having a single diameter, said groove-shaped reception area having a substantially constant inner diameter;
• a seal having a flange-like projection which engages within the groove-shaped reception area formed between said extensions, said flange-like projection being movably connected with said seal;
• a retaining ring inserted between said seal and one of the two extensions;
• said retaining ring having a greater external diameter than an internal diameter of at least one of said two extensions;
• and
• wherein, in use, said annular cap, said seal, said retaining ring and said extensions provide a coupling device which comprises one extension of the cap which is remote from the cylindrical housing and the other extension of the cap which is proximate to said end face of the housing, said flange-like projection on the seal being received in said groove-shaped reception area adjacent to said other extension, and said retaining ring being received in said groove-shaped reception area between said one extension and said flange-like projection.