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Rockford Speed Governing


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Gas Engine Patents of Note

In a perfect world, everything is built, well, perfectly. But alas, we don't live in a perfect world, so we must build to the best of our abilities, taking the advice and using the principles of others who came before us.

This patent, a "Governor for Explosive Engines," shows how not to build a governor. Although probably an effective design, it is overly complicated and uses far too many moving parts. Nevertheless, it would be very interesting to watch one of these Rockford engines run.

Its inventor, Frederick C. Zumdahl of Rockford, Ill., assignor to Rockford Engine Works, stated: "The object of this invention is to provide novel and effective means for automatically governing the speed of explosive engines."

How it Works

When the crankshaft (2) rotates, a spur gear on the end of the crank (14) meshes with another spur gear (15). This second spur gear (15) has a cam (17) attached to it. The cam makes contact with a roller (20) on the upper end (19) of the rocker arm (not numbered) mounted to the engine frame on a stud (18). The lower end of the arm (21) has a block (22) with a notch in it (23). One end of the bell-crank (24) holds an ad-justable detent (25). The beveled end (29) of the detent fits securely into the notch on the lower arm.

The other side of the bell-crank (30) has another arm attached (31). This arm has a shoe (32) on one end and a threaded rod (33) with nut (34) on the other. The rod is surrounded by a coil spring (36); another coil spring can be found between the nut (34) and bell-crank arm (24).

A lever (38) on the inside edge of the flywheel pivots at one end. The opposite end is connected to the flywheel via a spring (39), and can be adjusted by screwing the threaded rod (40) and jam nuts (41). This lever has a "projection" (42) extending from it, which makes contact with the shoe (32).

As the crankshaft and spur gears turn, they set the cam (17) in motion, making contact with the roller (20) and rocking the rocker arm. This will pull on the rod (13) and rock the bell-crank lever arms (9 and 10), thereby actuating the exhaust valve (7). As the flywheel rotates, the arm (38) is carried with it, which will cause the projection (42) to make contact with the shoe.

If the flywheel is spinning too fast, the projection cannot make contact with the shoe, due to centrifugal force. If the flywheel is spinning too slowly, the projection will make contact with the shoe, rocking the arm (31) and compressing the spring (36) to engage the detent so its beveled end will release from the notch. That will allow the rocker arm to move, thus allowing the exhaust valve to close.

When the projection is free from any contact with the shoe, a spring (43) holds the detent in the notch, which holds the rocker arm in place, effectively holding the exhaust valve open. Since no compression can be produced with the exhaust valve open, no power can be produced, either. "By this arrangement," says Zumdahl, "the exhaust valve is normally held open and permitted to close at the times an explosion is required."

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