| 摘要 |
A chin strap for a helmet comprises a strip of flexible material secured by one end to an anchorage within one side of the helmet and having a fastening on the free end of the strap which comprises a combination of firm elastic profile which can be engaged by a clamp within the other side of the helmet and released by a locking device which can be operated with one hand. Pref. the terminal profile comprises a springy polymeric or metallic core strip enveloped by an extrusion or injection moulding material to present a toothed rack profile flanked by smooth borders to pass beneath a guide collar supported by a chassis clamping block with a projecting arm. Engagement between the clamp and the endpiece of the strap is pref. maintained by a spring which can be overcome by a cam handle which can be turned by one hand to shift the arm between lock or release positions for the strap. Pref. the strap is of extruded polyester, linked to other components by stitched loops,lamination or rivets.
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