Exhaust diffusion apparatus

An exhaust diffusion device comprising a diffusion section including a plurality of annular rings defining a central passageway in communication with an engine exhaust system, said rings adapted to be retained in spaced apart relation to define a series of transverse open annular passageways;

• a tubular body defining an open central passageway communicating with the central passageway of said annular rings;
• movable valve means positioned in said open central passageway of said tubular body and positionable between a first position extending transversely of said passageway, and a second position in general alignment with the longitudinal axis of said passageway, said valve means including a butterfly rotatably supported within said open central passageway of said tubular member upon a shaft extending outwardly of said body, and positioning means being provided to position said butterfly in said first and second positions, and wherein said positioning means includes a knob rotatable upon said shaft and axially movable thereon;
• a compression spring interposed between said knob and said shaft urging said knob toward said body;
• a disc fixed to said body and defining at least one position defining aperture;
• a disc fixed for rotation with said shaft and defining at least one pin receiving aperture, said knob including at least one pin extending through said pin receiving aperture to engage said disc fixed for rotation with said shaft to rotate with said knob, said pin being of a length sufficient to engage said position defining aperture, and adapted to disengage said position defining aperture upon axial movement of said knob against the force of said compression spring.