When Stover Manufacturing & Engine Co. founder Daniel C. Stover died in 1908, he left behind a legacy of invention and innovation, with more than 100 patents to his name. The various companies — there were 10 all told — established by D.C. Stover between 1862 and 1916 manufactured a broad spectrum of agricultural and consumer goods.
Most of us associate Stover with gas engines, the first of which were produced experimentally as early as 1895, with full commercial production commencing by 1902. It’s known that Stover acquired many of the patents needed for engine production, but he was awarded several patents for his own work, including his very first, Patent No. 722,767, awarded March 17, 1903, “Apparatus for Cooling the Cylinders of Gasolene-Engines.”
As can be seen in the accompanying patent drawing, Stover’s design for an engine cooling tank with control valves was more evolutionary than revolutionary, perhaps reflecting his common sense approach to products. The patent focused on Stover’s use of a pair of coupled valves that could be opened and closed as needed to regulate the flow of cooling water from a cooling tank to a stationary engine and back.
Extremely simple in design, and by extension execution, Stover’s scheme featured little more than a system of levers and valves, the levers opening and closing cut-off valves at the top and bottom of a cooling tank. Although it’s not stated in the patent, it can be assumed from the lack of any pumping apparatus in his patent drawings that Stover was operating under the thermosiphon principle, where convection causes the heated water to rise, siphoning cooler water behind it.
In Stover’s design, the valves and actuating levers are all contained within the cooling tank. This has two obvious advantages. One would be protecting the mechanisms inside the cooling tank where, it would seem, they would be less likely to be inadvertently moved or damaged. The other, and one which Stover specifically noted in his application, is the advantage of using water pressure to help seal the valves on their seats. Located outside the tank, the valves would be holding back against water pressure. But located inside the tank, water pressure would help to hold the valve plates against their seats, ensuring a better seal.
One aspect that does seem curious, and is not addressed in the patent description, is the location of the main actuating lever inside the tank, accessible only by opening the top of the cooling tank. It would seem desirable for the lever to protrude from the top so the operator would not have to be in direct proximity to hot water. Then again, practical experience suggests it would be rare for the water to reach scalding temperatures, and this was, after all, a very practical design.