Hercules Engine News

Hvid History

| April/May 2003

  • Hvid engine's cylinder head

  • Logo

  • Hvid engine's cylinder head
  • Logo

If you don't know how it's supposed to be pronounced, the name 'Hvid' is a bit of a mouthful. A Danish name, it is simply pronounced 'veed.' Rasmus Martin Hvid was the man behind the name, and he held three of the five patents related to the fuel system used on the Thermoil brand engines and their many look-alikes.

Several years ago someone sent to me a copy of an advertisement for Penmac engines. The ad was from Melchior, Armstrong & Dessau, New York, N.Y., the exclusive foreign distributors for the Penmac engines, and the engine illustrated looked identical to the 6 HP and 8 HP Hercules-built Model U Thermoils.

The illustration at left, showing details of a Hvid engine's cylinder head, timing gears and injector, appears to have been used by various companies that produced the Hvid design of compression-ignition engines. Since most companies were using identical mechanical features, it's presumed they simply opted to take advantage of an available illustration. It's believed this illustration originated with Hercules Gas Engine Co., as it was the first in the U.S. to produce the Hvid engine design.

Just recently an inquiry came from Wayne Butler in New Zealand concerning a Penmac engine he has. After several e-mails, it has been determined Wayne's Penmac is a 3 HP engine produced by the Ker & Goodwin Machinery Company Ltd. of Brantford, Ontario Canada. The tag on Wayne's engine reads; 'Petroleum Engine & Manufacturing Co. of New York.' If you read carefully, you can see where the Penmac name came from.

In addition to the three patents held by Hvid, there were two other patents relative to the fuel system used on the Thermoils and their look-alikes. Jan Brons and Nanno Timmer of the Netherlands held the first of these two patents for a 'Hydrocarbon Engine.' It was applied for July 3, 1904 and awarded Oct. 22, 1907. Jan Brons held the second patent, which was applied for on April 13, 1907 and awarded on May 18, 1909.

On Feb. 2, 1912, Rasmus M. Hvid applied for the first of his patents for an 'Oil Injection Device for Oil Engines.' It was awarded on April 6, 1915. The patent for 'Means for Delivering Oil to Oil Burning Engines' was filed Aug. 16, 1912 and awarded April 6, 1915. The patent for 'Hydrocarbon Engine Governor' was filed on Dec. 16, 1913 and awarded on Dec. 28, 1915. Interestingly, the Sears catalogs note that the first Thermoil engines were built by Hercules in October 1915, before this last patent was issued.


Gas Engine Magazine A_M 16Gas Engine Magazine is your best source for tractor and stationary gas engine information.  Subscribe and connect with more than 23,000 other gas engine collectors and build your knowledge, share your passion and search for parts, in the publication written by and for gas engine enthusiasts! Gas Engine Magazine brings you: restoration stories, company histories, and technical advice. Plus our Flywheel Forum column helps answer your engine inquiries!

Be sure to take advantage of the Square Deal Subscription Program.

  • No Missed Issues.

  • No Renewal Notices.

  • No Additional Cost.

The Square Deal Subscription Program is designed as a paperless transaction with automatic renewals at a preferred low rate.   With advanced electronic notification, a 100% satisfaction guarantee and an easy opt-out plan, the Square Deal Subscription Program is the best value, risk free, eco-friendliest way to subscribe.

Facebook YouTube