Here’s a few more details on the cranes at the Marine Terminal Park. According to the National Register of Historic Places nomination form, the cranes were originally 15 ton oil burning, steam powered locomotive gantry cranes built by McMyler Interstate Company of Cleveland, Ohio in 1917. Twenty-eight of them were purchased by the new Hog Island shipyard in 1917. There is an excellent summary of Hog Island by John Lawrence on the also-excellent Encyclopedia of Greater Philadelphia
The steam gantry cranes have a 15 ton capacity at 15 ft. radius, mounted on tracks, with holding and closing lines and clam shell buckets of 3/4 and 1 1/2 yard capacity. Provision is made for magnets at 35 ft. radius with portable electric power. In 1952 they were overhauled and the boilers replaced. They stand on four legs, and are approximately 40 ft. tall.TAMS 1952
When the Hog Island Shipyard was being dismantled in 1930, Trenton purchased two cranes for the bargain price of $5,000 and they went into operation at the city’s new Marine Terminal in 1932. The cranes were listed on the National Register of Historic Places in 1980, after the Trenton Marine Terminal had ceased operations and the City was in the process of turning the cranes and the land they sat on into a park. The actual cranes were likely still on top of the gantries at that time, but were removed sometime after that, perhaps for safety reasons.
Kardas, S., and E. Larrabee, 1980. Hog Island Cranes. National Register of Historic Places Nomination Form.
Tippetts, Abbett, McCarthy Stratton (TAMS), 1952. Report on the Port of Trenton, Made for the City of Trenton and County of Mercer, New Jersey.