Which auxiliary brake device creates back pressure to enhance braking capacity?

The exhaust brake is an effective auxiliary braking device that uses back pressure in the engine's exhaust system to enhance braking capacity. When the exhaust brake is activated, it restricts the flow of exhaust gases, creating a backpressure effect. This increased pressure in the exhaust system effectively helps to slow down the vehicle without the need for traditional friction brakes. This method not only prolongs the life of the primary braking system but also provides more control, especially on downhill grades or during heavy load operation.

In contrast, the other options function differently: the transmission output retarder uses the vehicle's drive train to provide additional stopping power, often by using a friction element that creates resistance. The electromagnetic retarder operates using electromagnetic forces to create resistance, which is effective but relies on the vehicle's electrical system. The engine compression brake, while utilizing compression and decompression of the engine to slow the vehicle, does not specifically create back pressure in the exhaust system like the exhaust brake does. Each of these systems has its own advantages, but the exhaust brake uniquely capitalizes on back pressure to enhance braking effectiveness efficiently.