# What is "engine braking" on 18-wheelers and why is it banned everywhere? **URL:** \ **Category:** Factual Questions\ **Created:** [November 1, 2005, 12:40am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830 "2005-11-01T00:40:11Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![TLDRIDKJKLOLFTW](https://avatars.discourse-cdn.com/v4/letter/t/51bf81/32.png) [@TLDRIDKJKLOLFTW](https://boards.straightdope.com/u/TLDRIDKJKLOLFTW)\ **Post date:** [November 1, 2005, 12:40am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/1 "2005-11-01T00:40:11Z")
I often see signs in smaller towns that say “no engine braking!” in reference to trucks. I’d imagine that it’s noisy or somehow dangerous. Google searches only turn up manufacturers of engine brakes. What is it? Why’s it banned everywhere? ---
**Author:** ![mike1dog](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@mike1dog](https://boards.straightdope.com/u/mike1dog)\ **Post date:** [November 1, 2005, 12:45am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/2 "2005-11-01T00:45:17Z")
They’re referred to more commonly as “Jake brakes,” and [here’s a good explanation.](http://or.essortment.com/jakebraketruck_raio.htm) ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [November 1, 2005, 12:46am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/3 "2005-11-01T00:46:43Z")
And the [Straight Dope mailbag article on Jake brakes](http://www.straightdope.com/mailbag/mjake.html) from a few years ago. ---
**Author:** ![A.R.Cane](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)\ **Post date:** [November 1, 2005, 12:57am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/4 "2005-11-01T00:57:33Z")
Engine brakes are devices, installed on the head of diesel engines, that basically turn the engine into an air compressor. This makes the engine much more efficient in slowing the truck. Some truck owners run modified, or straight, mufflers in the belief that it improves engine performance. It probably does the opposite on modern, computer controlled, engines. When using the engine brake w/ stock mufflers the increased noise is minimal, but w/ more open exhaust systems they can be very loud. There are, of course, some who like this effect, but it is very annoying to residents of homes near truck routes, especially during early morning hours. You may notice that many of these signs specify no “unmuffled” engine brakes. The engine brakes are an important safety feature, as they aid in controlling downhill speed w/o excess braking, which can result in overheating and failure of the brake shoes. ---
**Author:** ![A.R.Cane](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)\ **Post date:** [November 1, 2005, 1:01am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/5 "2005-11-01T01:01:51Z")
Sorry, I’m a slow typist. Cecil’s article nailed it. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [November 1, 2005, 1:24am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/6 "2005-11-01T01:24:56Z")
Slight hijack: I’ve noticed in recent years that all the signs I’ve seen in California that used to say “Truckers: Easy on the Jake BrakeNext 5 miles” or something to that effect, now say “Engine” brake. The word “engine” is obviously a sticker/fresh paint or something that is covering up “Jake” since it is on a slightly different color background. Whats up with that? ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [November 1, 2005, 1:40am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/7 "2005-11-01T01:40:55Z")
> [@CynicalGabe](#): > > Slight hijack: > > I’ve noticed in recent years that all the signs I’ve seen in California that used to say “Truckers: Easy on the Jake BrakeNext 5 miles” or something to that effect, now say “Engine” brake. The word “engine” is obviously a sticker/fresh paint or something that is covering up “Jake” since it is on a slightly different color background. > Whats up with that? Read the Mailbag column, linked above. 😉 (P.S.: It’s a potential Trademark violation to use the term “Jake” brake when not speaking specifically about “Jacobs Engine Brakes”) ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 1, 2005, 1:45am UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/8 "2005-11-01T01:45:40Z")
> [@CynicalGabe](#): > > Whats up with that? The link supplied by \*tracer[\i] explains it. Basically, the Jacobs company doesn’t want their neame to be shorthand for “noisy trucks”. ---
**Author:** ![Who\_me\_1](https://avatars.discourse-cdn.com/v4/letter/w/958977/32.png) [@Who\_me\_1](https://boards.straightdope.com/u/Who_me_1)\ **Post date:** [November 1, 2005, 12:38pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/9 "2005-11-01T12:38:39Z")
> [@Xema](#): > > Basically, the Jacobs company doesn’t want their name to be shorthand for “noisy trucks”. Too late… ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [November 1, 2005, 2:32pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/10 "2005-11-01T14:32:16Z")
I used to wonder this, myself. Then last year when driving in Boston while on vacation, I heard this godawful loud “thwacka-thwacka-thwacka-thwacka” sound coming from the semi in the next lane. I exclaimed aloud to my husband, “What the hell is **that**?!” He said, “Engine braking.” My immediate response was, “No **wonder** you see all those signs forbidding it!” ---
**Author:** ![butler1850](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@butler1850](https://boards.straightdope.com/u/butler1850)\ **Post date:** [November 1, 2005, 4:15pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/11 "2005-11-01T16:15:47Z")
Having grown up at the end of a street, that had a sand & gravel pit at the other end of it, I think they should be outlawed, removed from all trucks, and destroyed in a public ceremony. I can’t tell you of the number of times, I had to say "Wait a minute, a truck is going by… :rolleyes: " as one kicked it’s Jake Brake on directly perpendicular, and only 30yds away from my bedroom window. My window seemed to be the spot at which EVERY truck decided, “Time to slow down for the stopsign ahead.” :mad: :mad: Actually, I know why we need them on the big trucks, and don’t REALLY want them actually outlawed, but some consideration would have been nice. Now I live far away from that street, and NEVER have a truck begin braking just outside my bedroom window! 😃 -OP : Banned because they’re trying to keep me from blowing up trucks, after I snap from “One too many” trucks slowing in front of my house. BRRRRRRRAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA \ -Butler ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [November 1, 2005, 4:21pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/12 "2005-11-01T16:21:26Z")
Why haven’t they ever been marketed on passenger cars? If they save brake wear and cause no additional engine wear, it would be better than downshifting to slow down. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [November 1, 2005, 4:29pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/13 "2005-11-01T16:29:41Z")
> [@DSYoungEsq](#): > > (P.S.: It’s a potential Trademark violation to use the term “Jake” brake when not speaking specifically about “Jacobs Engine Brakes”) Bah. Anyway, I need to go Xerox some paperwork… ---
**Author:** ![Incubus](https://avatars.discourse-cdn.com/v4/letter/i/c68b51/32.png) [@Incubus](https://boards.straightdope.com/u/Incubus)\ **Post date:** [November 1, 2005, 4:48pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/14 "2005-11-01T16:48:15Z")
> [@CookingWithGas](#): > > Why haven’t they ever been marketed on passenger cars? If they save brake wear and cause no additional engine wear, it would be better than downshifting to slow down. I’m guessing that they don’t scale down as well. A big eighteen wheeler with a trailer is going to have a lot of inertia. A small coupe with one passenger is not going to have nearly the kind of inertia, and typically can handle slowing down properly with its own brakes. ---
**Author:** ![The\_Chao\_Goes\_Mu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_chao_goes_mu/32/3191_2.png) [@The\_Chao\_Goes\_Mu](https://boards.straightdope.com/u/The_Chao_Goes_Mu)\ **Post date:** [November 1, 2005, 6:04pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/15 "2005-11-01T18:04:00Z")
> [@CynicalGabe](#): > > Bah. > > Anyway, I need to go Xerox some paperwork… On your way back will you grab a few Kleenex for me? I have a runny nose. ---
**Author:** ![askeptic](https://avatars.discourse-cdn.com/v4/letter/a/eb9ed0/32.png) [@askeptic](https://boards.straightdope.com/u/askeptic)\ **Post date:** [November 1, 2005, 6:11pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/16 "2005-11-01T18:11:05Z")
> [@The Chao Goes Mu](#): > > On your way back will you grab a few Kleenex for me? I have a runny nose. Since you’re up could you bring me a Band-Aid? ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [November 1, 2005, 6:13pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/17 "2005-11-01T18:13:08Z")
And on that note: [The Straight Dope mailbag article on trademarks used as generic terms](http://www.straightdope.com/mailbag/meponym.html) 😉 ---
**Author:** ![Skipper\_Too](https://avatars.discourse-cdn.com/v4/letter/s/6de8d8/32.png) [@Skipper\_Too](https://boards.straightdope.com/u/Skipper_Too)\ **Post date:** [November 1, 2005, 7:00pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/18 "2005-11-01T19:00:43Z")
> [@askeptic](#): > > Since you’re up could you bring me a Band-Aid? I just listen to my walkman when the loud trucks go by ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [November 1, 2005, 7:20pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/19 "2005-11-01T19:20:50Z")
A Pepsi would probably make your nose feel better. ---
**Author:** ![Ponder\_Stibbons](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponder_stibbons/32/343_2.png) [@Ponder\_Stibbons](https://boards.straightdope.com/u/Ponder_Stibbons)\ **Post date:** [November 1, 2005, 8:31pm UTC](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830/20 "2005-11-01T20:31:22Z")
> [@GaryM](#): > > A Pepsi would probably make your nose feel better. Personally, I don’t like that brand of coke. [Next page](https://boards.straightdope.com/t/what-is-engine-braking-on-18-wheelers-and-why-is-it-banned-everywhere/328830.md?page=2)