In 1935, Mr. E.W. Lamb of Middlesex presented an interesting three-cylinder, two-stroke radial engine with rotary head valves.

“Lamb engine”

-As original design it presented two characteristics that we can see in the engine cross-section.

“Schematic drawing of the Lamb engine”

-The pistons were double bore, the lower one being the largest and the mixture was blowing towards the upper and smaller diameter working piston. (see Prini et Berthaud engine or simply Berthaud).

-The other feature is the rotary valve (Aspin Type) but instead of continually turning it did it with pulses because it made use of a mechanism known as "Maltese Cross".

“Maltese Cross mechanism” (PeT=Wikipedia)

-This device was also used by film projectors to match the frame with the full shutter opening.