Abstract: A ring band adjustment structure of a crash helmet comprises a ring band, a connection sheet, a guide bar, and a pair of locating adjusters. Two ends of the ring band are connected to the locating adjusters. The locating adjusters are connected to the guide bar so that the locating adjusters can move along a guide track formed at the edge of the guide bar. Through a control element in a slide grooves of the locating adjuster, a point-shaped unidirectional locating element on the bottom face of the inner end of the control element will leave from a corresponding strip-shaped unidirectional locating element of the locating bar on the guide bar, and the locating adjuster can move. Each end of the guide bar has a limit element so that the locating adjuster will not slide out.

Abstract: A ring band adjustment structure of a crash helmet comprises a ring band, a connection sheet, a locating bar, and a pair of locating adjusters. Two ends of the ring band are connected to the locating adjusters. The locating adjusters are connected to the locating bar so that the locating adjusters can move along a guide track formed at the edge of the locating bar. By pressing a press element on the locating adjuster, a point-shaped unidirectional locating element on the bottom face of the locating adjuster will leave from a corresponding strip-shaped unidirectional locating element on the locating bar, and the locating adjuster can move. Each end of the locating bar has a limit element so that the locating adjuster will not slide out. Thereby, the diameter of the ring band can be adjusted, the structure is simplifier, and the manufacture and assembly are easier, hence facilitating modular processing.

Abstract: A ring band adjustment structure of a crash helmet comprises a ring band, a connection sheet, a guide element, an adjuster, a fixing element, and a locating element. The ring band has a long groove at each end portion thereof. A dentation is formed above the long groove of one end portion, and a dentation is formed below the long groove of the other end portion. The two end portions are inserted into two end faces of the connection seat. The guide element is inserted from a back face of the connection seat to penetrate the two long grooves. The fixing element passes a through hole in the guide element to join the adjuster. The adjuster drives the guide element to turn so that the two inserted end portions of ring band can move toward or away from each other.

Abstract: A ring-band adjustment structure of the crash helmet comprises a ring-band, a connection part and two adjustment parts. The accommodation groove of the connection part has two rows of positioning teeth with their teeth end on the top side. The two adjustment parts are connected to the two ends of the ring-band. The two adjustment parts are slid to match the positioning teeth. The two adjustment parts can be in the lock state or the adjustment state. The diameter of the ring-band can be adjusted properly according to the head of the user, resulting in steady positioning and comfortable wear. Simple structure and easy assembly make the production cost be reduced greatly.