| 摘要 |
PURPOSE: To prevent damages and establish a long service life by introducing an arrangement in which a first crest and a first trough are positioned opposing in the axial direction with respect to a second crest and second trough. CONSTITUTION: A flexible boot 10 as protective cover made of polymers has two sidewalls between its major diametric end 14 and a minor diameteric end 16, i.e., a folded side wall 12 consisting of a plurality of wall pieces in substantially tubular form and another 18 furnished with a wall portion 20, located outside in radial direction and substantially in a tubular shape. The wall portion 20 is coupled with a tubular wall portion 26 of the adjacent major end 14 via the crest 22 and trough 24 of the folded sidewall 12. The wall portion 20 constitutes a protective skin and is coupled with the mutually counter-facing crest 32 and trough 34 of the sidewall so that the outermost protection skin assumes a semi-doughnut form. The folded sidewall 12 continues to a third wall portion 36 substantially in a tubular shape, a crest 38, trough 40, any conical portion 42, and a fourth sidewall part 44 in a substantially tubular shape which is coupled with the minor end 16. The thickness of the sidewall is such that the crest and trough of the folded wall part are larger than the thickness of the wall part to couple them together so that the sidewall of the protection cover 10 are deflected.
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