| 摘要 |
2056400 9014778 PCTABS00002 Safety helmets, totally encasing the wearer's head and incorporate breathing apparatus supplying air to and exhausting air from an isolated volume within the helmet, are well know. The isolated volume is defined by a viewing panel, an annular seal and the face of the wearer. There is a problem in fitting and removing such a helmet which has been solved in prior art constructions by making the helmet from two shell halves, hinged together at the crown of the helmet. The invention proposes a one-piece helmet shell (11), which has a front to rear dimension more the one and a half times that of the wearer's head, and providing a pad (17, 20) so supported that it can be displaced to the rear regions of the helmet, to facilitate fitting and removal of the helmet, and with the helmet fitted pushes the head of the wearer into pressure contact with the annular seal.
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