How Does an Exhaust Brake Work?
Most exhaust brakes are hooked up so that you have a toggle switch mounted on the dash to turn on the Exhaust Brake Controls; the exhaust brake has a throttle position switch also. When the toggle switch is on and the throttle is released, the brake is activated (butterfly closed) to provide exhaust retardation. When the butterfly is closed it turns the engine “into an air compressor” by having to force air out of the engine under pressure (on the exhaust stroke). This causes the engine through its connection to the drive wheels to provide retarding power. The brake releases as soon as either the throttle is applied or the switch is flipped off. Exhaust Brakes on Automatic Transmissions In order to fully utilize the holdback of an exhaust brake, the torque convertor clutch must be locked up during deceleration. If the torque convertor is not locked up, then the drive wheels drive the torque convertor, not the engine. The exhaust brake has more hold back at higher rpm because of higher
