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Antique Engine Database
Rockford Engine Works
Rockford portable engines were built in 6, 8, 12, 15, 20, and 25 horsepower sizes. In addition, a 30 horsepower stationary engine was produced. The only major difference between the stationary and portable engines was the addition of a heavy cast iron sub-base on the stationary type. About 1910 Rockford added a series of hopper cooled engines to the line – these models were identical to the closed jacket style except for the method of cooling. The Rockford governor system was fully patent protected under No. 836,096 of November 20, 1906. Cormack and Zumdahl filed for the patent in February, 1904. This gear-driven governor provided extremely accurate speed regulation and also included a speed changing lever for on-the-go adjustment.
history
By 1904, or perhaps earlier, the Rockford line included sizes from 4 to 30 horsepower. The 4 horsepower model was of sideshaft design with the governor mounted near the cylinder head. Complete with cooling tank, battery box, fuel reservoir, and all sccessories, this skidded model was ready to run on delivery. Rockford claimed that “they are so perfectly balance that they require no fatening down, but will remain perfectly stationary wherever placed.” This 4 horsepower model weighed 1,250 pounds. Cormack and Zumdahl applied for their first engine patent on February 5, 1904. Some two years passed before Patent No. 813,081 was granted on February 20, 1906, covering a low tension igniter mounted in the cylinder head. It was actuated directly from the sideshaft.
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