Regarding Flywheel Forum 41/7/1 about Wisconsins in GEM, July 2006. This engine is about 4 HP, probably drove a belt-driven or directly coupled generator. Manuals for this engine may still be available from Wisconsin.
The Signal Corp. was the part of the U.S. Army that handled all types of communications: telephone, radio, telegraph, flashing lights, etc.
The Army serial number indicates it was an early production in the series, built under the contract for that equipment. The number built would have been given in the original contract. The Wisconsin serial number says it was built in about May of 1942.
It may have military specification parts on it; for instance, a cast iron head rather than aluminum, along with the steel rope sheave and different oil pan, which are mentioned. In generator service only, the running speed of the generator is the normal speed of the engine.
In regard to Hercules, the Jaeger Machine Co. built cement mixers and had the engines built by Hercules. Jaeger's color was blue, with very few, if any, changes from Hercules. Glenn Karch (firstname.lastname@example.org) can give a lot more information on these engines.