chin-piece

“Also, because of the bar down the middle, which was connected to the chin-piece, the shock of the blows to my head was distributed in an odd way, such that a lot of the force was going to my jaw.”

Simon & Schuster: The Double Life is Twice as Good

“Gisco slipped his fingers under his chin, for the chin-piece of the helmet used in course of time to occasion two callosities there; these were called carobs, and “to have the carobs” was an expression used to denote a veteran.”

Salammbo

“The berserk was sitting on his horse wearing his helmet, the chin-piece of which was not fastened.”

Grettir the Strong, Icelandic Saga

“In many cases a vizor, or other face protection, and a chin-piece are found in addition, so that this piece of armour is sometimes mistaken for an armet (_q. v._), but it can always be distinguished by the projecting brim in front.”

Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary"

“I devised an apparatus which consists of a simple cap fitting the head snugly; a cap of soft material fitting the chin; and a piece of elastic webbing tacked to the chin-piece and to the head-cap near the ears.”

With Sabre and Scalpel. The Autobiography of a Soldier and Surgeon

“Now that he sat at table he loosened the chin-piece, but he still presented almost the appearance of a masked man, for beneath the eyes was nothing but a confusion of unkempt tawny beard.”

Thorkild Viborg