If there's one element that visually defines Abenaque engines, it's the unique cooling system designed by John Ostenberg for Abenaque Machine Works owner Frederick Gilbert. Ostenberg eventually went on to found the Ostenberg Manufacturing Co. in San Jose, Calif., but he started his career in engine design and manufacture with Abenaque in 1894. During his time at Abenaque, Ostenberg applied for at least five different patents related to improvements for gas-powered engines, all of which were assigned to Gilbert.
While Abenaque made traditional hopper-cooled engines, we can safely assume Ostenberg's design was motivated by an appreciation of the limitations of hopper cooling, chief among them the constant replenishing of cooling water while working in the field. In his patent application of Jan. 21, 1901, Ostenberg stated that the 'main object of the invention is to obtain practical means for water-jacketing a portable explosion engine of the kind used, for example, in outdoor work, such as sawing wood and the like, where the base of operation is frequently changed.'
Ostenberg's invention neatly addressed this issue, employing a pair of horizontally oriented cooling tanks (some engines were equipped with a single, vertically oriented tank) to draw off engine heat from the cooling water. The tanks had a thin cross-section, ran more than the length of the engine and stood approximately 1-1/2 feet tall. Thermo-siphon action cycled hot water from the top of the cylinder into the cooling tanks at the front. The heated cooling water then flowed the length of the cooling tanks, during which time heat was drawn off. The cooled water then ran back to the engine from the rear.
A head-on view of the Abenaque cooling system as designed by John Ostenberg. The funnel for adding additional water was piped into the connections at the rear, which otherwise mirrored those at the front.
A 'T' connection at the front and rear of the tanks allowed cooling water to flow evenly into and out of both cooling tanks, and a funnel fitted at the rear 'T' allowed topping off of the coolant, if required. The cooling tanks' large surface area meant the system only needed a few gallons of water to effectively cool an engine, and an intended by-product of the design was the control of pre-ignition from overheating.
Side and top views of Ostenberg's cooling system as patented Nov. 18, 1902. Hot cooling water entered at the front through a 'T' connection (shown in detail in Fig. 2). The cooled water exited through a similar connection at the rear (b3 and b30 in Fig 1).
Ostenberg's clever design was incorporated into the majority of Abenaque engines, and there's little question but that it worked as intended. While not precisely a closed system, Ostenberg's design greatly limited the kind of evaporative coolant loss that standard hopper-cooled and screen-cooled engines experienced.
Thanks in large measure to Ostenberg's solid engineering skills, Abenaque prospered for 22 years before finally shutting its doors in 1916, a victim of increasing competition from larger manufacturers.
Further information on Abenaque Machine Works can be found in the booklet Abenaque Machine Works by Patricia A. Haas and Alice C. Caggiano, available through Farm Collector Books here at Gas Engine Magazine.
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