I photographed this broom press at a little hole-in-the-wall museum in the States a few years ago. They had it labelled as a "broom vise." It was designed to hold brooms in place so you could sew the bristles together. It had a patent date on it:
I looked it up when I got home, and voilà! Patented by David Bard of Cincinnati, Ohio. He assigned "one half of his right to George Flagg, of same place." I wonder what that was about?