Mystery Motor

I was attracted to this ad for little-known Waukesha-Hesselman engines primarily because of the overloaded truck featured in the ad’s photograph. But when I sat down to research the company for this blog entry, I came away with surprisingly little information. (I did find someone on Ebay selling this exact same ad. But the winning bid was only $5.99 – clearly not worth ripping pages out of the CCJ archives we keep here at the office.) As it turns out, I was really researching two companies and one engine.

Waukesha Engines were providing gasoline engines for a variety of applications, including heavy-duty trucking by the 1930s. The company is still doing business today as Waukesha-Dresser, specializing in large, stationary diesel engines.

I had more luck when I researched the Hesselman engine. Oddly enough, a Hesselman was a spark-ignited diesel introduced in Sweden in 1925 by engineer Jonas Hesselman. Basically, the engine was spark-ignition engine, converted to run on heavier fuels such as oil, kerosene or diesel. Fuel was injected into the combustion chamber using an injection pump. Because of the engine’s low compression, there wasn’t enough heat present to spontaneously ignite fuel in the combustion chamber as in a conventional diesel engine. Instead, fuel had to be ignited by a spark plug. Hesselman engines were often started on gasoline and then switched to diesel or kerosene when at working temperature. Clearing the heavy oil for the next start was achieved by switching back to gasoline before stopping. Historically speaking, Hesselmans were one of the first spark ignition engines that featured direct injection of fuel into the cylinder.

Hesselman engines were used by the Swedish truck manufacturers of the time: Volvo, Scania and Tidaholms Bruk, but were eventually usurped by conventional diesel engines.

Clearly, the Waukesha-Hesselman engine was a joint-venture between the two companies. I’m just speculating here, but I would guess that Waukesha was looking for a quick entry into the diesel engine business, which was really beginning to take off in the American truck industry by the late 1930s. At the same time, European truck manufacturers were beginning to pass Hesselman over in favor of more modern diesel engines, meaning Hesselman needed to find a new market to sell engines to.

Of course, the Hesselman was a technological dead-end. But this ad is a fascinating window into the rapidly-evolving technology that was being introduced in the 1930s.