What is something similar to a throttle in the intake pipe and exhaust pipe of a diesel engine? What is this for? How does it work? return

The throttle-like thing in the exhaust pipe is exhaust brake valve, which limits the engine speed; When a car goes down a long slope, it needs to rely on engine braking to limit the speed and share the burden of wheel braking. When descending a long slope, open the exhaust brake valve and close the exhaust pipe in exhaust brake valve to increase the exhaust resistance and limit the engine speed, so as to make the engine braking more effective. When driving to the normal road, turn off the exhaust brake valve and the engine will work normally. As for the intake pipe, the function and function of the installation parts are different because of the different intake (or intake heating) mode of each diesel engine. Please send a picture for reference.