In some areas of the country or in special situations, there was a need for natural gas fuel systems for gas engines. Hercules and Economy engines could be equipped to meet that need. As early as 1915, Sears offered Economy engines that were adapted to run on natural gas.
Some years later, a different natural gas mixer was offered. It is the one most likely to be seen and illustrated. It has a valve that shuts off the gas until there is enough vacuum on the intake stroke to lift the valve and admit the gas into the incoming air. Since natural gas pressure is normally very low, it only took the weight of the valve or a light spring to keep the valve closed until gas was needed. These engines could also be started and run on gasoline, if so desired. Not surprisingly, these kinds of engines were often found in oil and gas areas of Pennsylvania and West Virginia.
Other companies also made aftermarket natural gas attachments for Hercules-built en-gines. The Parkersburg Machine Co. of Parkers-burg, W.Va., made an attachment to fit on throttle-governed Her-cules engines. Several other companies also made natural gas attachments for Hercules engines, as well as for other engine manufacturers.
With the proper gas pressure and a good gas adjustment valve, these engines can easily be made to run on the LP gas of today. It is interesting to note that none of the Hercules natural gas attachments are ever mentioned in their catalogs, owner's manuals or parts books.
Glenn Karch is a noted authority on Hercules engines. Contact him at: 20601 Old State Road, Haubstadt, IN 47639; firstname.lastname@example.org