The Hercules Engine News

Thermoil engines

Content Tools

20601 Old State Road, Haubstadt, Indiana 47639

In one issue of the Sears and Roebuck catalog it states that the first Thermoil engines were produced at the Hercules factory at Evansville, Indiana, in October of 1915. The first Thermoils were listed only in the 1917 catalog and were available in the 2, 5 and 7 HP sizes. So far about 40 of these model T Thermoils are known. These models were prone to breakage problems because their construction was too light. They were built on modified gas engine castings. By 1917 the production of the model T Thermoil had been discontinued until a heavier Hvid type engine could be designed.

The instruction book and list of parts adds another dimension to these early Thermoils. In the parts list there is a column and a listing for parts for the 1 HP size. Further on there is a table showing the dimensions for constructing a masonry base to mount them on for permanent installation. In addition to the 1 HP information, there is also a dimension listing for the 9 HP size.

Up until recently, there has been no clue as to the existence of the 1 or 9 HP model T sizes. But that has changed now. A 1 HP model T Thermoil has surfaced. It is number 249. It is shown in the two pictures here. It is somewhat more modified in construction than the larger sizes. It has a two piece base, somewhat similar to the regular two piece base used on a few of the 1 HP Hercules engines. The flywheels appear to be identical to those used on the 1 HP Hercules and Economy engines of that time.

The engine pictured here appears to be complete except for the fuel line to the injector. It is unknown as to whether it has been run recently or not. The color is green. These early Thermoils were originally a sort of light lime green, with the typical Thermoil decal only with a red background.

During the August 2000 Tri-State Gas Engine and Tractor Show at Portland, Indiana, the new owner, Tom Buchanan of Indiana, Pennsylvania, picked up the engine. As was mentioned earlier, a 9 HP size is also listed. There have been rumors of such an engine existing, but so far no verification. It should be pointed out that this article refers to model T Thermoils and not the later models U or UA.