It is a reel-winch designed to collect the halyard on the winch barrel as does the spool collect line on a fishing reel. I have only seen a few of these since the late 1960's but they do work. We had two of them on our 1963 Rhodes Reliant--one each for the main and the mizzen. If the brake still works and will lock down the barrel/spool, there's no reason not to use it, especially so if you replace the wire halyards with something like 1/4" Spectra. Why spend money unnecessarily?
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."