LSJ
aor. with no pres. in use, inf. only in Hsch., elsewh. in 3 sg. ἔβραχε or βράχε ; — onomatop. Verb, rattle, clash, ring, mostly of arms and armour, δεινὸν ἔβραχε χαλκός Il. 4.420; βράχε τεύχεα χαλκῷ 12.396, Hes. Sc. 423, etc. ; βράχε δ’ εὐρεῖα χθών (with the din of battle) Il. 21.387; μέγας ἔβραχεν αἰθήρ A.R. 4.642; of a torrent, roar, βράχε δ’ αἰπὰ ῥέεθρα Il. 21.9; ἔβραχε δ’ ἅλμη Q.S. 14.527; creak, μέγα δ’ ἔβραχε φήγινος ἄξων Il. 5.838; shriek or roar with pain, ὁ δ’ ἔβραχε χάλκεος Ἄρης ib. 859; ὁ δ’ ἔβραχε θυμὸν ἀΐσθων (of a wounded horse) 16.468; shout a command, c. inf., A.R. 2.573.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)