Reprinted from the February 1996 issue of the
Gas Engine Magazine

Hercules Engine News
Including Economy, Arco,
Jaeger & Thermoil

by Glenn Karch
Old State Road
Haubstadt, Indiana 47639 .

HercNews2-96.jpg (43010 bytes)

The story about trademarks used on Hercules built engines continues with the Thermoils. Sears applied for the trademark shown below on November 10, l916, and claimed that it had been in use since August 16, 1916. It is stated in the spring 1917 Sears catalog that the first model T Thermoils were built in October of 1915. On the trade-mark illustrated below, the letters and perimeter were yellow and outlined in black. Some claimed the background was red, but on my later model U Thermoil the background was blue. Both yellow and black and yellow and black with a blue background have been seen on reproduction decals. The shape is very similar to that registered for the Economy engines as described in the previous article. On the Thermoil trademark, the center circle depicts a rotating wheel.

There is the question about what trademark was used on the Thermoils between October 1915 and August 1916. The only clue is found in the model T Thermoil instruction book. It shows an engine as illustrated at right with block letters on the water hopper. Presumably, these letters were yellow with a black outline. Known model T Thermoil serial numbers fall between 8 and 3743 with production ceasing sometime in 1917. It is conceivable then that a few hundred of the early Thermoils may have originally had the block lettering.

The same "bow tie" trademark continued in use during production of the models U and UA Thermoils from 1919 to 1924. When the contract with Sears expired or was terminated, Hercules continued to market the same 7 and 9 HP model UA engines as Hercules Oil Engines. They were painted Hercules green with red stripes and with the standard Hercules trademark.

Here's an interesting note and then a question. All known model T Thermoil engines are of the 2 1/2, 5 and 7 HP sizes. The instruction book also gives specifications for building foundations for 1 1/2 and 9 HP sizes. Does anyone out there know of any l 1/2 or 9 HP model T Thermoils? If so, please send owner's name and engine serial number to me. These engines should not be confused with the later 11/2 HP Model U built by Cummins or the later 9 HP model UA built by Hercules.

Return to the Hercules Gas Engine News index.

Return to the main page.