Called a "crowfoot" wrench because of its shape, this wrench was used in steam train repair work and to reach and to hold nuts and boltheads in difficult-to-reach places.
This tool is part of a collection of hand tools used in the inspection and repair of steam locomotives in the early- to the mid-20th century, roughly 1900-1955. Light repairs on steam locomotives were usually done in roundhouses at the many small locomotive terminals throughout a railroad's system; heavy repairs were done in a large, centralized repair shop serving the whole system (often referred to as the "Back Shop").