| 摘要 |
The protective helmet (FIG. 1) is provided in its lower part with a collar (C) formed advantageously by two segments (C1 and C2) movable with respect to each other slidably, in opposite directions along parallel horizontal guides (54-55) provided in an annular tapered crown (A1). Said shaped sectors terminate at their ends with two pairs of toothed racks (25-27 and 30-31), the elements of each pair being diametrically opposite with respect to their related actuating pinions (34-35) to achieve the simultaneous rectilinear movements in directions opposite to said segments to engage and disengage them with the jaw and head of the user. Segments (C1 and C2) are secured to body (A) of the helmet by guide elements (24,28,50) extending correspondingly and provided at their ends with blocking or stop means (60-64,51-65) which retain segments (C1-C2) in their retracted positions. |
