what does Engine Brake mean?

[Ready]

I've seen that sign on the road all the time and never knew what it means, I'm sure somebody here does though

 

[allanon1965]

engine brakes are used on tractor trailer rigs, they hold the exhaust valves open making the truck slow quicker in conjuction with the regular brakes, thats why they sound so loud! also known as Jake Brakes

 

[iamwiz82]

It's very loud when semis use engine brakes, so it's banned in many places.

 

[Pabster]

Banned, but rarely enforced. Jake Braking is almost a tradition around here

 

[Captante]

The term "engine-braking" refers to using engine compression to slow a vehicle down... an example would be shifting into a lower gear at the beginning of a large downgrade to save wear & tear on brakes & in the case of a large heavy truck to prevent brake overheating. A "jake-brake" is a system used by trucks with air brakes which increases engine compression a bit during engine braking & is mainly found on older 18-wheelers because of their less effective braking systems.

 

[allanon1965]

Sorry Captante, but you are wrong on how the jake brake works, here is the homepage and a small excerpt from the article http://www.jakebrake.com/products/hd-bleeder.php

it holds the exhaust valve off of its seat to bleed off compression while overcoming backpressure produced by the turbocharger vane turn-down system. While bleeding the compression against the backpressure, a pumping loss is created, converting the vehicle?s rolling momentum into retarding power.

 

[spidey07]

Originally posted by: allanon1965
Sorry Captante, but you are wrong on how the jake brake works, here is the homepage and a small excerpt from the article http://www.jakebrake.com/products/hd-bleeder.php

it holds the exhaust valve off of its seat to bleed off compression while overcoming backpressure produced by the turbocharger vane turn-down system. While bleeding the compression against the backpressure, a pumping loss is created, converting the vehicle?s rolling momentum into retarding power.

yep, those motors/drivetrains are very different that us 4 wheelers.

Also fun to see the "runaway tractor trailer" areas.

Basically a safe place to ditch the whole rig. Uphill with rows and rows of soft sand.

 

[Captante]

Originally posted by: allanon1965
Sorry Captante, but you are wrong on how the jake brake works, here is the homepage and a small excerpt from the article http://www.jakebrake.com/products/hd-bleeder.php

it holds the exhaust valve off of its seat to bleed off compression while overcoming backpressure produced by the turbocharger vane turn-down system. While bleeding the compression against the backpressure, a pumping loss is created, converting the vehicle?s rolling momentum into retarding power.

Ooops... thats what happens when you double-check facts after posting! Worst thing is that I have a CDL A & should have remembered that!

Edit: After doing some refresher reading, it seems the "Jake-brake" is actually a trademarked name & what it does is release engine compression on the pistons' downstroke in diesel engines to maximize compression breaking... seems those
signs that say "no Jake-brakes" are a sticky issue with Jacobs vehicle systems,
the manufacturer because actual Jake-brakes don't make the loud noise, but rather
poorly maintained exhust systems are to blame.

 

[Zap]

Originally posted by: spidey07
Also fun to see the "runaway tractor trailer" areas.

Basically a safe place to ditch the whole rig. Uphill with rows and rows of soft sand.

Better than seeing a tractor trailer in pieces covering half the road and shoulder.

Actually the runaway lanes are not always uphill. Even a downhill gravel path will stop a tractor trailer. I've heard that the one at the Mountain Springs grade East of San Diego will usually stop a tractor trailer within half it's distance.

 

[Rubycon]

They do that in the tunnels and it sounds like full auto artillery fire!