Question for the Leftpondians - completely OT ... :-)

[Arfa Daily]

OK. So I was watching an episode of the U.S. documentary series "Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it - white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?

Arfa

 

[tm]

Google "jake brake"


Tom

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:AWHFr.260203$C_6.232154@fx28.am4...

OK. So I was watching an episode of the U.S. documentary series
"Undercover Stings" a couple of nights ago, and the camera focused briefly
on a post by the side of the road. It had two square signs on it. The
upper green one said "Starke City Limit" which I understood, but the one
below it - white background, black lettering, black line all around the
edge, said "Engine Braking Prohibited". What does this mean ? I understand
what engine braking is - here in the UK at least - but does it mean
something different your side of the pond, and why would it be prohibited
anywhere ?

Arfa

 

On Sun, 24 Jun 2012 18:15:11 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

OK. So I was watching an episode of the U.S. documentary series "Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it - white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?

Arfa
If you don't want to google "Jake Brake" then I'll explain a little.

The exhaust valve is held open after the air is compressed in the
cylinder. A similar device used to be available, and probably still
is, for use on 2 stroke engine powered dirt bikes and they are both
compression release devices. So most of the energy used to compress
the air is lost before it can cause the piston to rebound. The reason
they aren't allowed in city limits is because they are so loud.
Eric

 

[Jeff Liebermann]

On Sun, 24 Jun 2012 18:15:11 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ?

As others have mentioned, using Jacobs Brakes is rather noisy. I used
to live in the dormatories at Cal Poly Pomona. Behind the dorms is
Kellogg Hill and the San Bernardino Freeway. Sleeping was sometimes a
challenge. The hill is rather steep and the truckers would user their
Jake Brake despite threats of dire consequences if caught. It was
explained that if they rode their brakes down the hill, it would
usually end up smoking by the time they arrived at the bottom. Safety
first.

For the non-truckers:
<http://farm3.staticflickr.com/2019/2059300689_8b09884913_z.jpg>

This version is more of a challenge:
<http://www.flickr.com/photos/delina/3403317633/>
Trucks without mufflers?

Perhaps adding "ignore this sign" might be useful?
<http://www.habitatadvocate.com.au/wp-content/uploads/2011/12/Trucks-avoid-using-engine-brakes-sign.jpg>




--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Arfa Daily]

"spamtrap1888" <spamtrap1888@gmail.com> wrote in message
news:10129962-66c0-46e0-a943-4911c1501914@x6g2000pbh.googlegroups.com...

On Jun 24, 10:15 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
OK. So I was watching an episode of the U.S. documentary series
"Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post
by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it -
white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine
braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?


http://www.jacobsvehiclesystems.com/technology/compression-release-brakes/

Hearing the jake brake's rowr rowr rowr (or blaaa aa aa aa aa) as big
trucks go downhill will keep you from sleeping.

Jacobs also makes exhaust brakes.

Ah-ha ! I thought that it might be something to do with trucks because with
most cars in the U.S. (at least the ones that I've driven) being auto
transmission, I couldn't imagine that there would be any way that engine
braking could easily be produced. I have heard of a Jake Brake on Ice Road
Truckers and IRT Deadliest Roads, but never really understood how it worked.
I don't recall them ever having commented about engine noise from using it,
but I guess that might not be too much of an issue in the wilds of Alaska or
Canada. In saying that though, I would have thought that it would have been
picked up on the soundtracks of those programmes if it was that loud ?

I have no idea whether there is a similar system fitted to UK trucks, but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not. I have seen signs here though at the
start of long downhill grades that tell trucks to engage a low gear, and
that was my understanding of what the term "engine braking" meant - taking
advantage of the engine's inherent compression, multiplied by the low gear
ratio, to produce an overun 'drag' to prevent the truck running away in a
manner that couldn't be readily corrected by use of the brakes, because of
brake fade, which I've also seen mentioned on IRT. Is this not the same
thing ? What is the difference / advantage of the Jake Brake over what I've
described, given that it is apparently noisy ?

Arfa

 

[Phil Hobbs]

Arfa Daily wrote:

"spamtrap1888" <spamtrap1888@gmail.com> wrote in message
news:10129962-66c0-46e0-a943-4911c1501914@x6g2000pbh.googlegroups.com...
On Jun 24, 10:15 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
OK. So I was watching an episode of the U.S. documentary series
"Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post
by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it -
white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine
braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?


http://www.jacobsvehiclesystems.com/technology/compression-release-brakes/

Hearing the jake brake's rowr rowr rowr (or blaaa aa aa aa aa) as big
trucks go downhill will keep you from sleeping.

Jacobs also makes exhaust brakes.


Ah-ha ! I thought that it might be something to do with trucks because with
most cars in the U.S. (at least the ones that I've driven) being auto
transmission, I couldn't imagine that there would be any way that engine
braking could easily be produced. I have heard of a Jake Brake on Ice Road
Truckers and IRT Deadliest Roads, but never really understood how it worked.
I don't recall them ever having commented about engine noise from using it,
but I guess that might not be too much of an issue in the wilds of Alaska or
Canada. In saying that though, I would have thought that it would have been
picked up on the soundtracks of those programmes if it was that loud ?

I have no idea whether there is a similar system fitted to UK trucks, but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not. I have seen signs here though at the
start of long downhill grades that tell trucks to engage a low gear, and
that was my understanding of what the term "engine braking" meant - taking
advantage of the engine's inherent compression, multiplied by the low gear
ratio, to produce an overun 'drag' to prevent the truck running away in a
manner that couldn't be readily corrected by use of the brakes, because of
brake fade, which I've also seen mentioned on IRT. Is this not the same
thing ? What is the difference / advantage of the Jake Brake over what I've
described, given that it is apparently noisy ?

Arfa

It doesn't heat up and boil the brake fluid when you're coming down a
mountain pass with a full load. (Here in NA we have real mountains.)

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

 

[(PeteCresswell)]

Per Robert Macy:

"Engine Braking Prohibited", way out in the wilds, no one around.

Plus, the slope was so gentle? Maybe for the trucks?

They're *really* loud.... as in you don't want tb within even
miles of the noise - especially, I'd think, on wide-open country
without a lot of trees/hills to mitigate it.

As far as the gentleness of the slope goes, I don't have any
experience with heavily-loaded trucks, but I'd guess that if any
braking at all is required, the first choice from a cost-savings
perspective would be the compression brake, since it doesn't wear
out any consumables.
--
Pete Cresswell

 

[Robert Macy]

On Jun 24, 10:15 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:

OK. So I was watching an episode of the U.S. documentary series "Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it -  white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?

Arfa

Interesting! Just saw this sign real!.

Driving towards Flagstaff, AZ on Highway 17 saw a sign that said
"Engine Braking Prohibited", way out in the wilds, no one around.

Plus, the slope was so gentle? Maybe for the trucks?

Could be pollution? There was no way an automobile's engine would
brake on that slope. Must be to keep the trucks from trying to save
their brakes.

 

[spamtrap1888]

On Jun 24, 10:15 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:

OK. So I was watching an episode of the U.S. documentary series "Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it -  white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?

http://www.jacobsvehiclesystems.com/technology/compression-release-brakes/

Hearing the jake brake's rowr rowr rowr (or blaaa aa aa aa aa) as big
trucks go downhill will keep you from sleeping.

Jacobs also makes exhaust brakes.

 

[spamtrap1888]

On Jun 24, 11:40 am, Robert Macy <robert.a.m...@gmail.com> wrote:

On Jun 24, 10:15 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:

OK. So I was watching an episode of the U.S. documentary series "Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it -  white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?

Arfa

Interesting! Just saw this sign real!.

Driving towards Flagstaff, AZ on Highway 17 saw a sign that said
"Engine Braking Prohibited", way out in the wilds, no one around.

Plus, the slope was so gentle? Maybe for the trucks?

Could be pollution?  There was no way an automobile's engine would
brake on that slope.  Must be to keep the trucks from trying to save
their brakes.

Couldn't find a reference in the Arizona Revised Statutes, but here's
the law in Oregon. The offense of engine braking requires use of an
engine brake that is unmuffled. So letting your gas engine rev up down
hill would not be an offense.

http://www.oregonlaws.org/ors/811.492

§ 811.492š
Engine braking

• penalty
• exception

(1) A person commits the offense of engine braking if the person is
operating a motor vehicle on a highway and uses an unmuffled engine
brake.

(2) The offense described in this section, engine braking, is a Class
A traffic violation.

(3) A person is not in violation of this section if the person uses an
unmuffled engine brake in an emergency situation to avoid imminent
danger to a person or to property. [1993 c.314 §7]

 

[Peter Hill]

On Sun, 24 Jun 2012 16:00:41 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

I have no idea whether there is a similar system fitted to UK trucks, but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not. I have seen signs here though at the
start of long downhill grades that tell trucks to engage a low gear, and
that was my understanding of what the term "engine braking" meant - taking
advantage of the engine's inherent compression, multiplied by the low gear
ratio, to produce an overun 'drag' to prevent the truck running away in a
manner that couldn't be readily corrected by use of the brakes, because of
brake fade, which I've also seen mentioned on IRT. Is this not the same
thing ? What is the difference / advantage of the Jake Brake over what I've
described, given that it is apparently noisy ?

Arfa

It doesn't heat up and boil the brake fluid when you're coming down a
mountain pass with a full load. (Here in NA we have real mountains.)

Neither does overrun engine braking without compression release.
Suck, squeeze, phut, blow.
The suck provides a bit of braking as it's on a shut throttle at idle
setting and the vacuum resists the piston downward motion.
The squeeze doesn't do much as it's not got much air to squeeze.
The bang usually isn't. Mixture will be so far off it misfires.
Injection systems cut the fuel.
The blow does most braking as exhaust valve opens before BDC the
cylinder will suck air in from exhaust and then expel it on the up
stroke.
It's effective on small vehicles but not trucks. To stop a truck the
engine would be revved to destruction before it did anything really
noticeable.

Release of compression.
Suck, blow, suck, blow.
The compression release valve is un-throttled so a large volume of air
is induced/expelled. Pumping losses are very high resulting in a lot
(about x4) more braking than overrun braking.

I don't think anyone in Europe uses them. That's why we have sand drag
"escape" roads on steep hills that descend more than a few 10's of
meters.
--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!

 

[Phil Hobbs]

Peter Hill wrote:

On Sun, 24 Jun 2012 16:00:41 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

I have no idea whether there is a similar system fitted to UK trucks, but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not. I have seen signs here though at the
start of long downhill grades that tell trucks to engage a low gear, and
that was my understanding of what the term "engine braking" meant - taking
advantage of the engine's inherent compression, multiplied by the low gear
ratio, to produce an overun 'drag' to prevent the truck running away in a
manner that couldn't be readily corrected by use of the brakes, because of
brake fade, which I've also seen mentioned on IRT. Is this not the same
thing ? What is the difference / advantage of the Jake Brake over what I've
described, given that it is apparently noisy ?

Arfa

It doesn't heat up and boil the brake fluid when you're coming down a
mountain pass with a full load. (Here in NA we have real mountains.)


Neither does overrun engine braking without compression release.

<snip>
Piston engines are about 80% efficient as compressors, iirc. So the
amount of braking from overrun with a shut throttle is small. Also,
diesels don't have throttles!

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

 

[John-Del]

On Jun 24, 4:06 pm, "(PeteCresswell)" <x...@y.Invalid> wrote:

They're *really* loud.... as in you don't want tb within even
miles of the noise - especially, I'd think, on wide-open country
without a lot of trees/hills to mitigate it.

Well, they're not THAT loud. In hilly residential areas they frown
upon them. Around here, truckers also use them instead of the
standard brakes to scare the beejeezus out of people who cut in front
of them or otherwise drive like jerks. Drivers know a horn is
intentionally applied, but don't understand the horrible noise a truck
on the jake bearing down on them is making.

John

 

[Arfa Daily]

"Peter Hill" <peter.usenet1@nospam.demon.co.uk> wrote in message
news65fu75frj0aqsemabf2jal15sbt8jhrn1@4ax.com...

On Sun, 24 Jun 2012 16:00:41 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:


I have no idea whether there is a similar system fitted to UK trucks,
but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not. I have seen signs here though at the
start of long downhill grades that tell trucks to engage a low gear, and
that was my understanding of what the term "engine braking" meant -
taking
advantage of the engine's inherent compression, multiplied by the low
gear
ratio, to produce an overun 'drag' to prevent the truck running away in
a
manner that couldn't be readily corrected by use of the brakes, because
of
brake fade, which I've also seen mentioned on IRT. Is this not the same
thing ? What is the difference / advantage of the Jake Brake over what
I've
described, given that it is apparently noisy ?

Arfa

It doesn't heat up and boil the brake fluid when you're coming down a
mountain pass with a full load. (Here in NA we have real mountains.)

Neither does overrun engine braking without compression release.
Suck, squeeze, phut, blow.
The suck provides a bit of braking as it's on a shut throttle at idle
setting and the vacuum resists the piston downward motion.
The squeeze doesn't do much as it's not got much air to squeeze.
The bang usually isn't. Mixture will be so far off it misfires.
Injection systems cut the fuel.
The blow does most braking as exhaust valve opens before BDC the
cylinder will suck air in from exhaust and then expel it on the up
stroke.
It's effective on small vehicles but not trucks. To stop a truck the
engine would be revved to destruction before it did anything really
noticeable.

Release of compression.
Suck, blow, suck, blow.
The compression release valve is un-throttled so a large volume of air
is induced/expelled. Pumping losses are very high resulting in a lot
(about x4) more braking than overrun braking.

I don't think anyone in Europe uses them. That's why we have sand drag
"escape" roads on steep hills that descend more than a few 10's of
meters.
--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!

We do have sand drag escape roads here, although not many of them. There is
one at the bottom of a very long downgrade on a road in Devon that I used to
travel on regularly when going to carry out service work at a site that was
a customer of mine at the time. I think that I'm beginning to understand the
difference now, and I'm pretty sure that we do not have them fitted here -
in the UK at least. There are some fairly steep grades scattered around the
UK, but most of the mountainous areas are in Wales and Scotland, both of
which are fairly sparsely populated, so not too much truck traffic other
than on the main roads, which are largely flat. There are plenty of
mountainous areas in mainland Europe though, so you might have thought that
trucks operating in these areas might employ such supplemental braking ?

Arfa

 

[spamtrap1888]

On Jun 24, 12:34 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:

I have no idea whether there is a similar system fitted to UK trucks, but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not.

A quick google shows Jacobs brakes are fitted to ERF (Foden) trucks,
which use Cummins diesel engines. I couldn't find anything regarding
Perkins' engines.

I have seen signs here though at the
start of long downhill grades that tell trucks to engage a low gear, and
that was my understanding of what the term "engine braking" meant - taking
advantage of the engine's inherent compression, multiplied by the low gear
ratio, to produce an overun 'drag' to prevent the truck running away

Unlike in a spark ignition engine, apparently, in a Diesel, air is
free to move through the cylinders. (A spark ignition engine's
throttle changes the amount of air, and thus fuel, flowing through the
engine. The Diesel's airflow is constant; the accelerator pedal
changes the amount of fuel flowing only.) Thus the engine's inherent
compression is immediately followed by the engines's inherent
expansion, with only a negligible net slowing effect. The Jake brake
interrupts the flow and changes the engine into an air compressor.

in a
manner that couldn't be readily corrected by use of the brakes, because of
brake fade, which I've also seen mentioned on IRT.

Brake fade is related to heat. When sufficiently hot, the coefficient
of friction of the brake lining of the (in heavy trucks, still drum
shoes) is relatively low. There are other causes of fade, too. Here at
the tops of hills, you will see spots to pull over and let your brakes
cool.

Is this not the same
thing ? What is the difference / advantage of the Jake Brake over what I've
described, given that it is apparently noisy ?

Here's an interesting historical treatment with some description, but
mostly focusing on the inventor:

http://files.asme.org/ASMEORG/Communities/History/Landmarks/5577.pdf

 

[Peter Hill]

On Mon, 25 Jun 2012 01:14:23 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

We do have sand drag escape roads here, although not many of them. There is
one at the bottom of a very long downgrade on a road in Devon that I used to
travel on regularly when going to carry out service work at a site that was
a customer of mine at the time.

There is one on A379 into Dartmouth.
http://goo.gl/maps/uwyl

There is another on A46 at Bath on approach from Pennsylvania
http://goo.gl/maps/jVYo
--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!

 

[Cydrome Leader]

Arfa Daily <arfa.daily@ntlworld.com> wrote:

"spamtrap1888" <spamtrap1888@gmail.com> wrote in message
news:10129962-66c0-46e0-a943-4911c1501914@x6g2000pbh.googlegroups.com...
On Jun 24, 10:15 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
OK. So I was watching an episode of the U.S. documentary series
"Undercover
Stings" a couple of nights ago, and the camera focused briefly on a post
by
the side of the road. It had two square signs on it. The upper green one
said "Starke City Limit" which I understood, but the one below it -
white
background, black lettering, black line all around the edge, said "Engine
Braking Prohibited". What does this mean ? I understand what engine
braking
is - here in the UK at least - but does it mean something different your
side of the pond, and why would it be prohibited anywhere ?


http://www.jacobsvehiclesystems.com/technology/compression-release-brakes/

Hearing the jake brake's rowr rowr rowr (or blaaa aa aa aa aa) as big
trucks go downhill will keep you from sleeping.

Jacobs also makes exhaust brakes.


Ah-ha ! I thought that it might be something to do with trucks because with
most cars in the U.S. (at least the ones that I've driven) being auto
transmission, I couldn't imagine that there would be any way that engine
braking could easily be produced. I have heard of a Jake Brake on Ice Road
Truckers and IRT Deadliest Roads, but never really understood how it worked.
I don't recall them ever having commented about engine noise from using it,
but I guess that might not be too much of an issue in the wilds of Alaska or
Canada. In saying that though, I would have thought that it would have been
picked up on the soundtracks of those programmes if it was that loud ?

I have no idea whether there is a similar system fitted to UK trucks, but I
can't say that I've ever heard anything that sounded out of the ordinary
with a truck engine, so maybe not. I have seen signs here though at the

I wonder if vehicle size difference is part of the reason jake brakes
would seem to be less common outside the US.

a large truck in europe is small here in the US.

I think only Australia outdoes the US with their road trains.

It's the same with railways, a large european freight train would be
crushed to bits in a crash with a commuter passenger train from the US.
Laws here don't permit passenger trains to be made of paper cups and used
tissue like in germany. Everything is large and heavy.

Canada does run longer heavier trains than in the US though.

 

[gregz]

John-Del <ohger1s@aol.com> wrote:

On Jun 24, 4:06 pm, "(PeteCresswell)" <x...@y.Invalid> wrote:



They're *really* loud.... as in you don't want tb within even
miles of the noise - especially, I'd think, on wide-open country
without a lot of trees/hills to mitigate it.



Well, they're not THAT loud. In hilly residential areas they frown
upon them. Around here, truckers also use them instead of the
standard brakes to scare the beejeezus out of people who cut in front
of them or otherwise drive like jerks. Drivers know a horn is
intentionally applied, but don't understand the horrible noise a truck
on the jake bearing down on them is making.

John

http://www.youtube.com/watch?v=qocMoTOVn6Q

Greg

 

[Jon Elson]

Peter Hill wrote:

The suck provides a bit of braking as it's on a shut throttle at idle
Uhhh, there's no throttle on a Diesel.
setting and the vacuum resists the piston downward motion.
The squeeze doesn't do much as it's not got much air to squeeze.
The bang usually isn't. Mixture will be so far off it misfires.
There will be no fuel sent to the cylinders when the compression brake

is applied.

It's effective on small vehicles but not trucks. To stop a truck the
engine would be revved to destruction before it did anything really
noticeable.

Actually, the Jacobson brake is QUITE effective, and can deliver about the
same braking effort as the engine at full power.

Jon

 

[Arfa Daily]

"gregz" <zekor@comcast.net> wrote in message
news:453742454362455664.711461zekor-comcast.net@news.eternal-september.org...

John-Del <ohger1s@aol.com> wrote:
On Jun 24, 4:06 pm, "(PeteCresswell)" <x...@y.Invalid> wrote:



They're *really* loud.... as in you don't want tb within even
miles of the noise - especially, I'd think, on wide-open country
without a lot of trees/hills to mitigate it.



Well, they're not THAT loud. In hilly residential areas they frown
upon them. Around here, truckers also use them instead of the
standard brakes to scare the beejeezus out of people who cut in front
of them or otherwise drive like jerks. Drivers know a horn is
intentionally applied, but don't understand the horrible noise a truck
on the jake bearing down on them is making.

John

http://www.youtube.com/watch?v=qocMoTOVn6Q

Greg

OK. I guess that puts it in perspective. So, was the driver's foot off the
pedal all the way down that incline, after he'd switched on the Jake brake ?
Why did the sound drop right down at the bottom, before the switch was
disengaged ? Is it because the engine is no longer in over-run condition, or
because accelerator has been reapplied ?

Arfa