| 摘要 |
Two rigid coaxial tubular elements (101) are held apart with a tubular spacing element (2). Each tubular element comprises two half shells (101.1, 101.2) which are fastened along one edge (103). Each tubular element includes front and rear sections with different conicity. A film (107) covers the outer surface of the tubular elements, and supports the elastic sleeve (5). The structure comprises two rigid coaxial tubular elements (101), with a tubular spacing element (2) situated between the inner ends of the tubular elements. Each tubular element comprises two half shells (101.1, 101.2) which are fastened together along one rectilinear edge (103) by pins or a tongue and groove fitting. They are made from a plastic material, with a roughened external surface. Each tubular element includes a front section (105) with a strong conicity (pref. 50 degrees) and a rear section (106) with a low conicity (pref. less than 1 degree). A film (107) covers the outer surface of the tubular elements, whilst the sleeve (5) lies outside this film. The film is attached to tensioning elements. |
