Patent ID: 6899079

Claim:
In an exhaust-operated brake system for an internal combustion engine, the improvement comprising: a valve configured for disposition in an enclosed path transmitting an exhaust stream from said engine, said valve being configured to provide substantially restriction-free passage of said exhaust stream through a first passageway, comprising a conduit disposed through a seal member, when said seal member is oriented in a first position, and to provide an increased restriction through a second passageway, to increase a back-pressure in said exhaust stream, operable to resist high-rpm-rotation of said engine while permitting operational rotation of said engine at an idle-speed, when said seal member is rotated into a second position, wherein; said seal member is configured and arranged such that, at said second position, an axis of said conduit is disposed substantially at right angles to an exhaust stream flow direction at an inlet into said valve, and wherein said valve comprises: a clamshell housing defining a cavity and third and fourth orthogonal passageways disposed to intersect approximately at a center of said cavity, said third passageway defining said inlet and an outlet for said exhaust, with a first seal surface arranged to circumscribe a junction between said inlet and said cavity; a said seal member being disposed in said cavity, said seal member being supported between first and second stub axles, said first and second stub axles being disposed for rotation about an axis in common with said fourth passageway to orient a second seal surface, carried by said seal member, in non-contacting harmony with said first seal surface when said seal member is disposed at said second position; and a linkage system arranged to rotate said seal member between said first position and said second position.