Macomber made a "barrel" or "revolver" type engine, similar to many others such as the Perfetti, Trebert, Oerlikon, etc

“Macomber, photo”

-The Macomber engine had air-cooled cylinders and entered the market around 1911 for Macomber Rotary Engine in Los Angeles, California.

-But the engines were built at the Avis Engine Company of Allston in Massachusetts.

-It had seven cylinders located axially around the engine shaft, having at one end an articulated inclined plate, whose periphery was driven by the ends of the connecting rods.

-Unlike other similar engines, the compression and stroke was variable depending on whether the engine rotated at idle or at normal speed.

-This happened through a gear at the front that could move the inclined plate.

“Macomber engine schematic drawing”

-The ignition was provided by a Bosch magneto.

-It could rotate as slow as 150 rpm up to 1500 rpm. It gave 50 HP at 1,000 rpm.

From Appendix 6: The Macomber Engine Patent for (perhaps land) vehicle No. 1042018, dated 1912, now appears in a book on these engines.

“Patent for the first Macomber engine”

-Viewing the lever on the right, it acts on the oscillating plate giving a variable stroke to the pistons and therefore power and rotation speed. Maybe it wasn't a very practical idea.

“Book about the Macomber engines”

-Macomber engines were as good for aviation applications due to the regular operation of these devices, as they could be for railways.

-One of the favorable arguments was that it had a very small frontal area compared to its other engines equivalent in power.

"Macomber engine on a bench"
(from the above mentioned book)

-Inventor Macomber initially made a barrel-type engine to be installed and tested in a car. that was known as the Eagle-Macomber.

“Macomber engine installed on a car” (PiP=pm)

-In the above illustration we can see the valve rocker arms, and closer the manual starter lever that is connected to the motor shaft.

“Staff member with a Macomber engine” (PiP=pm)

-He has the engine on his lap to demonstrate the absence of vibrations and smooth running despite its alternative mechanism and oscillating plate.

From Appendix 9: We have more information about this engine, along with two new photographs that show us two positions of the oscillating plate.

This engine was presented at the beginning of the last century as a new Rotary engine, with the cylinders rotating precisely, for a possible solution to the problems of compaction and volume of multi-cylinder engines for cars and airplanes.

-The model pictured here is the 60 HP engine with rpm variation, between 200 and 1500. It works with the four-stroke cycle.

“Side view of a faired Macomber”

-It was invented by Walter G. Macomber, and had a lever that drove a front gear that varied the inclined plate, achieving control of stroke and compression in the cylinders.

“With the oscillation plate at 0”

“With the oscillation plate at maximum angle”

From Appendix 10: We show two new illustrations of this engine and like most of them, they are on the same wooden bench.

“Macomber engine accessories side view”

-These illustrations correspond to the 7-cylinder Model “A” giving 50-60 HP. It is manufactured by the Macomber Rotary Engine Company of Los Angeles, CA.

“Macomber from a different angle”

-It weighs 230 lbs, which is a lot for the power it delivers. We can see the shape of the rocker arms.

-And a third photo of another model in which the intake ducts stand out. It has 7 cylinders and is known as the "Eagle Macomber". We see the magneto at the front.

“Macomber Eagle engine”