BOLT, tr. of the Heb. נָעַל, H5835, appears only in 2 Samuel 13:17, 18 in the KJV. It is tr. “lock” in other passages (Judg 3:23, et al.). The word has no other cognates in the Sem. languages except late Heb. and Syr. Although its primary meaning is associated with an identical root referring to leather or sandals, locks and bolts in antiquity were made of both wood and metal. These locks were usually fastened from within but some were designed for large elaborate keys. The “burning coals” (Hab 3:5 KJV) are more precisely “fiery bolts” as in ASV.
International Standard Bible Encyclopedia (1915)
The ancient Hebrews had fastenings of wood or iron for the doors of houses (2Sa 13:17,18; So 5:5), city gates (Ne 3:3,6,13-15), prison doors, etc. (Isa 45:2), which were in the form of bolts. These were sometimes pushed back from within; but there were others which, by means of a key, could be unfastened and pushed back from without (Jud 3:23 ff). These were almost the only form of locks known.
See Bar; Locks.
In Hab 3:5, resheph (a poetic word for "flame") is rendered "fiery bolts" (the King James Version "burning coals"). It seems to denote "the fiery bolts, by which Yahweh was imagined to produce pestilence or fever" (Driver, Deuteronomy, 367).