Signs saying "No engine brakes" - Why?

bluestraveller · 20th June 2008, 21:13

I have seen sign boards that say "Do Not Use Engine Brakes" on quite a few roads on the US. I have never really understood this but my closest guess would be noise pollution? Can anybody elaborate?

aah78 · 20th June 2008, 21:57

Yes, you've understood correctly. That's a warning for trucks.
It's mostly due to the loud noise that engine brakes produce when engaged but the warning may also be displayed in case there's a chance of slipping (eg. icy roadways).

For technical details on engine brakes, you can look up Google.

Ever heard a sudden loud noise - like a machine gun going off inside your head - while driving on the freeway? That's the semi in the next lane using his engine brake.

Sankar · 21st June 2008, 00:27

Here are couple of you tube videos on jake braking trucks.

YouTube - jake brake

YouTube - n14 cummins diesel with no mufflers and jake brake

Randhawa · 21st June 2008, 19:49

Engine brakes with trucks is something to do with opening the exhaust valves to TDC to slow down the engine hence reducing the brakes without actually applying the brakes.

noidaboy · 23rd June 2008, 03:54

According to the 2nd video it does sound like machine gun being fired.

20th June 2008, 21:13	#1
bluestraveller BHPian Join Date: Jan 2008 Location: ಕರ್ನಾಟಕ Posts: 117 Thanked: 5 Times View My Garage	Signs saying "No engine brakes" - Why? I have seen sign boards that say "Do Not Use Engine Brakes" on quite a few roads on the US. I have never really understood this but my closest guess would be noise pollution? Can anybody elaborate?
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20th June 2008, 21:57	#2
aah78 Team-BHP Support Join Date: Feb 2004 Location: NYC / BOM Posts: 4,662 Thanked: 3,258 Times View My Garage	noise & slip Yes, you've understood correctly. That's a warning for trucks. It's mostly due to the loud noise that engine brakes produce when engaged but the warning may also be displayed in case there's a chance of slipping (eg. icy roadways). For technical details on engine brakes, you can look up Google. Ever heard a sudden loud noise - like a machine gun going off inside your head - while driving on the freeway? That's the semi in the next lane using his engine brake.
	() Thanks

21st June 2008, 19:49	#4
Randhawa Senior - BHPian Join Date: Oct 2007 Location: Brighton Posts: 1,193 Thanked: 355 Times	Engine brakes with trucks is something to do with opening the exhaust valves to TDC to slow down the engine hence reducing the brakes without actually applying the brakes.
	() Thanks

23rd June 2008, 03:54	#5
noidaboy BHPian Join Date: Jul 2006 Location: Noida Posts: 1,003 Thanked: 268 Times View My Garage	According to the 2nd video it does sound like machine gun being fired.
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