Share the road: What’s the engine brake’s purpose, and how do you use it?

Dial 530-408-6423 to record a message that could contribute to the Overdrive/Radiotopia coproduction of the Over the Road podcast — the first listener question we’re hoping you’ll answer: “What’s the purpose of the engine brake and how exactly do you use it?” Bonus: “Are jakes always really loud? Why or why not?”