nhbenz is correct. It is a tool used by crate builders or for opening up wood crates.
Once upon a time, wood crates were widely used for shipping. During the 1910's, through the 1930's (and probably longer than that), Ford Motor Company had entire departments of crate builders, and entire departments of crate openers. Ford even had a department that salvaged lumber and nails out of the crates. The lumber went to the crate building department, and the scrap nails were sent to the steel furnaces for the making of new steel.