# So, what's so bad about engine retarder brakes? **URL:** \ **Category:** Factual Questions\ **Created:** [August 3, 2001, 5:44am UTC](https://boards.straightdope.com/t/so-whats-so-bad-about-engine-retarder-brakes/74750 "2001-08-03T05:44:31Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [August 3, 2001, 5:44am UTC](https://boards.straightdope.com/t/so-whats-so-bad-about-engine-retarder-brakes/74750/1 "2001-08-03T05:44:31Z")
The Beloved and I are just back from a car holiday, and we noticed that in a lot of towns, as you came in, there was a sign like: “Please Do Not Use Engine Retarder Brakes” or “Use of Engine Retarder Brakes Prohibited in City Limits.” So, a two-part question: what are engine retarder brakes, and what’s so bad about them? ---
**Author:** ![Sultan\_Kinkari](https://avatars.discourse-cdn.com/v4/letter/s/7bcc69/32.png) [@Sultan\_Kinkari](https://boards.straightdope.com/u/Sultan_Kinkari)\ **Post date:** [August 3, 2001, 5:55am UTC](https://boards.straightdope.com/t/so-whats-so-bad-about-engine-retarder-brakes/74750/2 "2001-08-03T05:55:03Z")
IANAT(trucker) but I think it might be those noisy compression brakes. It may be something about noise pollution. ---
**Author:** ![Ginkgo](https://avatars.discourse-cdn.com/v4/letter/g/3bc359/32.png) [@Ginkgo](https://boards.straightdope.com/u/Ginkgo)\ **Post date:** [August 3, 2001, 5:55am UTC](https://boards.straightdope.com/t/so-whats-so-bad-about-engine-retarder-brakes/74750/3 "2001-08-03T05:55:44Z")
Straight Dope Science Advisory Board to the rescue! [What are “jake brakes” and why are they prohibited in some locations?](http://www.straightdope.com/mailbag/mjake.html)