Word Study
hammer-beam
CIDE DICTIONARY
hammer-beam, n.
A member of one description of roof truss, called hammer-beam truss, which is so framed as not to have a tiebeam at the top of the wall. Each principal has two hammer-beams, which occupy the situation, and to some extent serve the purpose, of a tiebeam. [1913 Webster]
For further exploring for "hammer-beam" in Webster Dictionary Online