From book " Aviation Equipment Red Book ", 1944 :
Crane manufacturers ---- these are only " mobile " type, does not include " traveling " cranes such as used overhead in factories, hangars, etc :
Barnett-Cravens Co. Chicago, Ill.
Canedy-Otto Mfg Co. Chicago, Ill.
Conco Engineering Works Mendota Ill.
Detroit Hoist and Machine Co. Detroit, Mich
Elwell-Parker Electric Co. Cleveland, Oh
Harnischfeger Corp Milwaukee, Wis
Hill Acme Co, Canton Div. Cleveland Oh
Lewis-Shepard Products Inc Watertown, Mass
Manning, Maxwell & Moore Inc-- Shaw-Box Crane & Hoist Div Muskegon, Mich
Morgan Engineering Co Alliance, Oh
Reading Chain & Block Corp Reading, Pa
Robbins & Meyers Inc Springfield, Oh
Roeper Crane & Hoist Works Trenton, NJ
Silent Hoist Winch & Crane Co Brooklyn, NY
Sterling Tractor Equipment Co New York, NY
Vogler Co Inc St Louis, Mo
Williamette Hyster Co Portland, Or
Wright Mfg Div, American Chain & Cable Co York, Pa
Hoist manufacturers ---- Manual only, not including hydraulic, electric, traveling :
Beebe Bros Seattle, Wa
Clipper Mfg Co St Louis, Mo
Coffing Hoist Co Danville, Ill
Conco Engineering Works, Div H. D. Conkey & Co Mendota, Ill
Downs Crane & Hoist Co Los Angeles, Ca
Federal Aircraft Works Minneapolis, Minn
Independent Pneumatic Tool Co Chicago, Ill
Manning, Maxwell & Moore Inc--Shaw-Box Crane & Hoist Div Muskegon, Mich
Pacific Engineering Corp Los Angeles, Ca
Sedgwick Machine Works New York, NY
Speidel Elevator Corp Reading, Pa
Union Mfg Co New Britain, Conn
Voight & Son Co Buffalo, NY
Whiting Corp Harvey, Ill
Yale & Towne Mfg Co Philadelphia, Pa
As you can see, there are lots of manufacturers, and in the book, it does not tell who had govt. contracts for supplying military equipment, but I'm sure most manufacturing was geared to military aircraft needs and military aircraft builders factories --- Boeing, Lockheed, etc ---, and if it is listed as being a supplier of these items, it means they were making the item, not " changed over " to making something else for the war effort.
With this list of manufacturers, maybe you can research further for drawings, plans, photos, etc