How's a Diesel Exhaust Brake works?
Referring to this picture will help simplifythe explanation of the under-vehicle operation.
An oversized nodular iron housing consisting oftwo stainless steel butterflies (one large, one small) is added to the exhaust systemin front of the muffler. The small butterfly operates in a separate waste gate by-passport and the large version in the main passage. Notice the large electric solenoidmounted to the nodular housing and protected with the stainless steel heat shield.
When signaled, the solenoid instantly; closes thelarge butterfly (bottom illustration), creating immediate exhaust pressure for assistingthe vehicle's regular brakes. Exhaust flow is now directed through the small by passport and released by the small butterfly at a pre-determined pressure. This allowsfor the fastest pressure build-up possible and maintains it longer. Pretty "slick"...huh?