What is the correct way to use an exhaust brake?
4 Answers
The correct way to use an exhaust brake: A regulating valve is installed on the engine exhaust pipe. By closing this valve, the pressure during the exhaust stroke is increased, and the resulting negative pressure is utilized to obtain braking force. Below are the precautions for using an exhaust brake: 1. Throttle at zero: When the exhaust brake is in use, the accelerator pedal should be at the zero position, and the fuel injector stops injecting fuel. If the accelerator pedal or clutch pedal is pressed, the exhaust brake will automatically shut off, preventing engine stalling when stopping and exhaust brake activation during fuel injection. 2. Prohibited in poor road conditions: It is best not to use the exhaust brake on icy, snowy, or slippery roads, as there is a risk of driving wheel slip and skidding.
I've been driving heavy trucks for over a decade, and exhaust brakes require skillful operation. You need to activate the switch two kilometers before a long descent, letting the engine gradually build resistance. Maintain steady RPM above 1800 for effectiveness – too low actually harms the engine. The key is combining it with main brakes: first apply foot brake to reduce speed, then let the exhaust brake maintain velocity. Never use it recklessly in rain or snow – wheel lockup is far more dangerous. After every trip, I disassemble the valve to clean carbon deposits; seizure would mean serious trouble. Remember, this device assists rather than replaces – never skip proper braking when needed.
I learned this trick last time when driving the Qinghai-Tibet line with my master. Simply put, the exhaust brake is about blocking the exhaust pipe of a diesel engine, forcing the engine to slow down. There are three key points: First, you must be in a low gear to use it; pressing it in neutral is useless. Second, activate it in advance when you see speed limit signs downhill—it's no use if you're already speeding. Third, listen to the sound! A change to a muffled 'thud-thud' is normal, but if you hear a 'clang,' turn it off immediately. Newbies often make the mistake of suddenly activating the exhaust brake on dry roads—the sudden deceleration can be terrifying. Oh, and never try it on flat roads; you could wreck the turbocharger.
With twenty years of truck repair experience, I've seen countless cases of damaged exhaust brakes. The correct usage is to engage it when descending steep slopes in 9th gear or below, maintaining engine speed around 2000 RPM for optimal effect. Here's a tip: watch the temperature gauge! Turn it off immediately if the coolant exceeds 95°C, or prepare for an overhaul. There's a technique when using it with regular brakes – first lightly apply the brakes to reduce to a safe speed, then activate the exhaust brake to maintain speed. Special reminder for diesel vehicle owners: regularly check the solenoid valve, preferably spraying the valve body with cleaner monthly. Frozen valves in northern winters cause too many accidents.
