Safety helmet with improved adjustment

摘要

The helmet has an adjustment mechanism (15) with a rotary adjustment knob (16) to adjust a headband to size of a user's head. A latch occupies latched and unlatched positions to respectively prevent and allow driving of the knob in rotation. The mechanism includes a double cog-wheel (17) having a sprocket (18) associated with a drive rack (19) of a neckband of the headband, and another sprocket (20) associated with a drive rack (21) of a securing strap of the headband. The sprockets have different diameters to achieve differential driving of the securing strap and the neckband.