I find myself increasingly fascinated by patent drawings concerning early gas engines, as they afford us a window into the evolution of engine design. Pioneer engine designers were keen on divining new and unique methods of engine operation, and their approach to a problem was often driven by the necessity to overcome existing patents that could limit their aspirations.
For example, Nikolaus Otto’s 1877 U.S. patent for the 4-stroke internal combustion engine included the two-to-one camshaft/crankshaft gears to time valve opening and closing. This presented a significant obstacle to independent innovation, but inventive engineers designed “gearless” engines that used eccentrics rather than gears to control valve timing.
As the industry matured, engine designs continued to evolve. Governors to control engine speed are an example. There were simple designs, such as applied to hit-and-miss, with flywheel-mounted weights acting to interrupt valve or ignition operation. And there were complicated designs, including the artfully engineered cam-stopper arrangments used by companies such as Callahan and Columbus. Other designers came up with their own solutions, such as the governor designed by Peter Mohrdieck and used in Frisco Standard engines built by Standard Gas Engine Co., San Francisco, California.
As you can discover, Mohrdieck’s (patent No. 824,564) used a rotary valve to modulate the volume of the fuel/air mixture to the cylinder, the first application, so far as I know, of a rotary valve in a gas engine.
Likely expensive to manufacture due to the number of working parts and machined castings involved, Morhdieck’s design was yet in many ways brilliantly simple and precise. Essentially, it transferred rotational output from the crankshaft into longitudinal action at the governor back into rotational action at the valve. The spinning governor pushed a shaft that rotated a barrel-shaped valve to control the volume of fuel and air admitted into the intake stream ahead of the intake valve. Standard used this design on single-cylinder and multi-cylinder engines up through the 1910s, although at some point it was apparently modified to use a conventional butterfly valve.
For stationary farm use, Mohrdieck’s approach would have been unnecessarily complicated, but for marine applications, Standard’s major market, it would likely have been ideal in the early days of the industry, enabling finely tuned, consistent engine operation. Continuing advancements ultimately rendered Morhdieck’s design obsolete, but it’s interesting to examine today, a novel chapter in the evolution of the internal combustion engine.