Frederickson engines were built by the World's Motor Co. of Bloomington and Chicago. (also Fredrickson sometimes).

-They were rotary engines with 5 and 10 cylinders.

-The 5A was the 5-cylinder and gave 70 hp at 1,000 rpm, with 377 cu. in. of displacement, and a 2-stroke cycle.

“Frederickson 5A”

-The 10A had ten cylinders and was the result of joining two 5As.

-The pistons of both engines had deflectors in the head to assist the best sweep inside the cylinder.

“Frederickson engine and cylinder cross-section”

-This two-stroke rotary engine had a unique feature: the pre-compression of the mixture to be introduced into the cylinder was made in the lower part of the piston, closing this chamber with a kind of funnel through which the connecting rod slides.

From Appendix 9: We obtained a photograph of the 5-cylinder rotary engine.

“From the maintenance manual”

-In reality the name of Frederickson is the brand, as we see, the manufacturer is the World's Motor Company.

-The engine is two-stroke, with an ingenious device inside the radial block that divides the crankshaft space from the piston space.

-Besides, it is oscillating. It consists of some kind of funnels, one for each connecting rod, isolating each part.

-Each funnel has an oscillating ball joint. The cones are inclined following the movement of the connecting rod and at maximum inclination they open the passage (B and C) for the mixture that flows in through the support shaft. This allows the mixture to pass from the crankcase to the lower interior of the cylinders.

-When the piston descends, it compresses the mixture under it.

“Frontal and side cross-sections”

“Connecting-rod position details”

-In the sections of the cylinder in B and C we can see that the porthole (P) gives way from the bottom to the top. And from there - under the piston - it will pass to the top when the ports are open.

-The exhaust ports are higher -like all two-stroke engines- and communicate directly to the outside of the cylinder.

FREDRICKSON (it is Frederickson most of the time) .- USA. In a magazine from 1910 appears a drawing of the 5-cylinder rotary engine with this name written: "Fredrickson Motor" when we have always known it as "Frederickson ..."

“With the name Fredrickson Motor”