Hi,
I guess there is a subject opened in the forum, I think so. Meanwhile, I should ask you to what period exactly you refer, because the Republic lasts from 509 BC to 27 BC, with the Principate, and in those 500 years you have many changes...
About equipment, you can find some pieces of information in the Goldsworthy book "The complete roman army"; in the Michael M. Sage "The republican roman army"; and also in "Roman military equipment" from M.C. Bishop and J.C.N. Coulston. I talk about english-written books, because in spanish (my mother tongue
)there are several works about it in Fernando Quesada Sanz's books, José Manuel Roldán Hervás, Antonio Duplá, Guillermo Fatás or Francisco Marco Simón, among others.
Of course, there is the famous Polybius book about the roman army, written in the II Century BC.
Surely they carried helmets, shields and armours, but is a too wide and not well known period to say something more especific.
Hope this could be of some help.
David P. Sandoval
(Ludi Laietani - Athenea Promakhos)