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Diesels do so have engine braking. more engine braking than gasoline engines; though much more still with the Jake brake, which is useful when running as much as 250 lbs per horsepower.
@@MickPsyphon because Jacob’s is the name of the company that makes it. There are other brands, Blue Ox, Williams, although those names are probably relics of the past. There are exhaust brakes, essentially closing the exhaust off. And there are engine brakes, that basically turn the engine into an air compressor.
Studies have proven that the sound of a Jake Brake is significantly quieter then the sounds of a truck coming through your house or car! I live in the mountains, and love hearing trucks on the Jake!
Well of course it’s quieter then the sound of a truck coming through your house well or at least i would hope I’m just joking dude I know what you mean
Growing up, my dad owned a grading company and at his peak he had 25 Mack trucks with belly dump trailers and 6 end dump trucks, all with Cat engines. Sometimes on days when I was off school, I’d ride around with the different drivers, or sit in the cab of a bulldozer with the operator. Sometimes they’d let me drive a big twin engine 627 Cat scraper or 953 front end loader or some other pieces while sitting on the lap of the operator. By the time I was 14, I was pulling those big Mack’s into the lube bay at the shop, doing oil changes and greasing them under supervision of one of the mechanics. I loved the sound of the Jake’s coming on, man. That quick little clip brought back many fond memories.
We had a service manager who would always pull the wire connectors OFF behind the dash. Shut of MACK engine brake. I would carry a wrench to pull off the Dash plate and hook the wire back up. If I drove the MACK dump that day.
The Kingdom of God is at Hand John 3:16 King James Version 16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
I'm a trucker and my brother was asking me what was that loud sound on trucks. Not being a mechanic myself, I only knew it all happened in the engine, so I'm sharing this with him so he can understand. He has worked on gasoline engines, and he's a Master Technician This is a perfect video explanation for me, and now, for him Thanks!
I’ve lived close to a highway for over a decade and there is nothing better than hearing a fully loaded, pre-emissions log truck hammering on the jakes.
@@A.R.77 I don't like having to pause conversation or otherwise adjust my life due to some juvenile driver hammering their jakes on the flat highway a few hundred feet from where I live. And I feel even more ire toward the idiots who tune their puny automotive Diesels to maximize noise and smoke. And there are those masculinity-challenged men children who full throttle their pretend race cars all the time just to make some sort of stupid point about their man-hood.
Jake brakes. Designed by Cummins founder Clessie Cummins and was about the only thing he was able to take with him when he lost his company. After loosing the company, he knew his financial salvation was to be the engine brake, unfortunately, he didn't have the money to build them. He went everywhere trying to come up with financing to make it happen. Finally he approached Arthur Jacobs of Jacobs drill chucks, who was thrilled by Cummins invention. He promised to bankroll the operation....one condition being his name would be front and center in all advertising and communications .hence 'Jacobs engine Brake'....or 'Jake Brake' for short
Engine braking is fundamentally linked with compression ratio. In Europe we can also compare this pretty easily since we often drive manual transmissions and petrol, as well as diesel cars. A diesel has a lot more engine brake compared to a petrol engine of similar size. Jake brakes, exhaust gas brakes, retarders, etc. are used only on trucks since the available engine brake would not be enough for the weak power to weight ration of a fully loaded truck.
Having driven petrol and diesel 4x4's off road, I refuse to own a petrol 4x4 because of the diesels superior engine brake, due to its high compression ratio. I'm also a truck driver familier with exhaust brakes and engine retarders. The point of an exhaust brake is to block air flowing out and thus increase the engines compression ratio. These systems help a lot when you are in the WRONG GEAR. Going down a hill in a high gear causes the transmission to over power the engines compression, hence the auxiliary braking systems to increase that compression. The compressed air in the compression stage doesn't "spring back" all that efficiently. Sure, it's not as effective as a Jake brake, but it's still 10x more effective then a petrol engine. BTW, anyone who thinks a thin air intake butterfly valve is strong enough to slow a couple ton of moving vehicle on its own is an idiot. There is a lot more physics behind it all.
Yeah. Thought the same thing. My diesel has more engine braking than a comparable gasoline engine. Only problem is that a truck wheigs a lot more and thus is accelerated a lot more downhill. So you can't compare a car, where need to bring the energy of 1.5 tons into heat, to truck where you need to convert the energy of 40 tons into heat.
@@dragonfire3289 did I forget to mention the part about where I drive trucks and auxiliary braking systems are meant to be used when you stuff up and use the wrong gear going down a hill? Yes, trucks weight more, but they also have larger engines often with much longer bore strokes, have larger boxier aerodynamic profiles, more tires in contact with the ground etc. All the things that hurt efficiency and fuel economy, actually help slow down a truck. Yes they take longer to slow down and yes auxiliary braking systems help a lot, but with the correct use of the foot brakes and the right gear selection, not a single truck on this planet ACTUALLY needs Jake brakes, exhaust brakes, engine retarders etc.
@@35manning Dummy!You have never driven a fully loaded truck down a mountainous road!--Reality with the real possibility to die is different to a video game!
Once place I lived there was a road behind my street, I'd hear trucks used their jakes all the time, always a symphony of various engines, miss that place, loved the sounds.
I definitely DO want to hear Jake Brakes in my town. I grew up next to a hill on a major highway in Central Pennsylvania and I absolutely loved hearing those Jake Brakes all day and night!
True story: the inventor of the "Jake Brake" was one Clessie Cummins. Yes, THAT Cummins. He couldn't convince the executives at the company he founded to buy his idea, so he sold it to the Jacobs company. Hence the name.
A Diesel engine provides much more engine braking than a spark ignition engine. Compression of the air with 18:1 Compression ratio generates plenty of heat. All that heat energy results in the vehicle slowing down.
Thank you ahaha when I heard that I was like wtf ahaha diesels are great for the fact that they engine brake, the Jake’s are just an even better brake so you don’t have to use your service brakes and fade them out on a hill
No diesel has a butterfly in the intake unless you have a jake or some kind of engine retarder they will run right past the governor even in low gear going down a steep hill
Nonsense. I've been driving trucks for 35 years and can tell you that loaded or empty, if you lift off the power there's no noticeable drag at all. Remember that compression pushes the piston back down with the same force. Current engine brakes involve the turbo creating back pressure. They are not only quieter, they are a lot more effective than the old Jakes. I can take a max weight truck down the Grapevine and only occasionally touch the brakes.
~2:20 I used to work on fighter jets. We had a mneumonic to remember the 4 stages of jet engine operation, which are pretty analagous to 4-stroke engine operation. "Suck, Squeeze, Bang, Blow" - Intake, compression, combustion, exhaust. This was taught in the official training.
I’ve tried watching videos on how Jake brakes work and never really got a good understanding until this video. Finally I understand Joe they work. Thanks
Thanks for the excellent graphics and explanation. I’m a new CDLClass A, and looking for a dump truck to start out. This was by far the best explanation of how a Jake brake works I’ve seen.
For those that enjoy the twisted history of diesel engines, the story of Clessie and his betrayal by the Miller family (again) led to the formation of the company we know as Jacobs, as in Jake brake. That personal story of the Jake brake is even more interesting than the Jake brake by itself. The betrayal and feud exists to this day, a century later.
@@benjaminturpin2749 Clessie Cummins, original founder of the Cummins diesel engine company. One of the biggest researchers into the early development of the diesel engine.
Thank you... big time. From time to time I've tried to find out how a Jake brake works and only found idiot phrases like 'changes the airflow thru the engine to provide braking', as if the audience had no idea what goes on inside an engine. Your explanation was superb.
Thanks for this informative video! I had heard of Jake brakes and now I know how they work. I have heard the sound of a Jake brake all of my life, and I like the sound of them, as long as they aren't in my neighborhood. Good video, sir!
When a Diesel engine is under no fuel, the engine works to compress the air in the cylinder. If no fuel is added, that compressed air will push back down on the piston making for neutral braking. On a Jake brake with no fuel yes the engine works to compress the air in the cylinder, but the exhaust valve opens near top to expell the compressed air hence their is no air pressure left in the cylinder to push the piston back down again-and you get all the compression strokes working as a brake-usually around 400hp of braking.
400Hp of engine braking only at High RPM with all cylinders actively providing braking effort. Also not all engine brakes pop the exhaust valve open near the top of the compression stroke some will actively partially open the valve at the start of the compression stroke and will remain partially open through nearly the entire compression stroke. The piston has to work against the restriction of the valve and sometimes also and exhaust brake downstream of the turbo. This is done to cut down on noise
@@j.m.5995 The original Jake brakes were activated by the injector-hence they opened the exhaust valve near top dead center and at the highest compression pressure-which made for a noisy Jake Brake. Now most Diesels have a separate lobe on the camshaft to operate the Jake brake making them both more effective and quieter.
@@Tchristman100 Was this on overhead Cam engines? I can see how the injector lobe on a pump injector setup could be rigged up to Piggly back off the mechanism to pop open the exhaust valve as it essentially fires fuel at the same time you would want to activate the exhaust valve. I don't know how they could do this on a injector pump setup but I guess where there's a will there's a way lol cheers to Jacobs and their Engineering whose work has spare many a countless life through out the span of time
@@j.m.5995 On engines with an injection pump (like my Caterpillar 3406B mechanical) the Jake brakes work off cross activation. For instance number 1 cylinder is on compression but number three is on exhaust. So number one gets Jake Brake activation by the exhaust valve activating the Jake brake from cylinder 3 to work one. It works OK-just not very strong.
That would be interesting. Years ago I went over Donner pass and grapevine almost every night and I saw many trucks in the run off ramp. Always felt bad for those drivers. I'm sure some of them had to change they're drawers after they got stopped
can't understand why any one would object to the sound of a jake brake. to me it is like the laughter of children. I actually feel a boost of energy when i hear a jake brake. i guess energy is never lost, acording to issac newton.
Greatest view at night: trucks with open stacks, with Jake brakes on, going down "the grapevine " in California in the early 80s. Flames three feet high coming out the stacks.
That was a pretty good explanation. Years ago I worked for a major motor coach manufacturer. There were 3 basic types of auxiliary brakes offered. Jacobs brakes, transmission retarders (Allison), and magnetic driveline brakes.
I have a exhaust brake on my 2500 Cummins and a 5in unrestricted pipe and when I'm coming home you hear it sounds like a big rig love that sounds... and when I go to the city the sound bouncing off the buildings is great
Had a Jake brake fail on a mountain pass in Colorado. My boss was driving. We were 80,000 lbs. To keep from runaway he kept it low gears and was pumping the brakes. Motor stressed and blew close to the bottom. I imagined what sitting on a bomb would be like. I bounced off the headliner. Speed was OK at this point, let it let run out on the flat & got it pulled over, oil trail behind us. No cell phones back then. Hitched a ride to a phone & called the agent we rented the tractor from. He wanted to know if we were prepared to pay for the blown motor. I ask him if they would've been prepared to pay for our funerals. They towed another tractor to us & dragged the casualty away. We didn't hear about paying for that motor again.
There's a story on the net about how Clesey Cummins (yes, that Cummins) came to invent the jake brake. He was in California in the 1930's with a truck going down hill and narrowly missed a train when he couldn't stop. Cummins invented the jake, but his own company refused to buy it, so he sold it to Jacobs. Clesey Cummins only worked for Cummins, he didn't own it.
The story i heard from a person that was a personal friend of clesey & tested the engine for clesey . The story is the bankers that financed the engine co would not back the engine brake , because they thought it would comprise the engine & ruin the engine & its reputation . So there you go bankers screwing things up AGAIN!!
Who doesn’t love a Jake brake and who starts looking all around when you hear one to see what kinda old school beautiful rig that’s Jake Breaking lol I do
I love the sound that old trucks make while engine braking. active sound design can probably replicate it but at a tolerable noise volume for newer trucks
Love that sound, I lived next to a highway hill section. It would shake the house, awesome. It would give me enough time to see a decked out rig go buy.
Ngl I had no idea what Jake breaks were I just loved hearing this sound growing up in the woods living off the road. But WOW this happens every second maybe more??? Engines are beautiful
I was wondering how a old-school big cam 4 Cummins gets its valve timing for the jake brake apparently off oil pressure but how does it get the timing ? thanks
It gets the altered timing from the engine brake. When the engine brake is activated by oil pressure the master piston is pushed down on the injector adjusting screw and when it is pushed up adjusting screw pushes up on master piston which pushes the oil on slave piston to push it down & opens the exhaust valve which gives the compression blow down ( that where the noise comes from) & then closes to give a vacuum in the cylinder to give more retardation . ( depends on enging ) . That is the best i can explain with out going to great detail.
In most diesel commercial car (at least as old as 2002 I would say) there is a throttle valve at the intake for the EGR. This throttle is also used for engine breaking
A throttle at the intake can't generate net braking. It just determines the fraction of incoming air that is fresh vs EGR. Either way, the intake will get a given quantity of air and no braking will result. However, you CAN produce braking by throttling the exhaust and this is often used to "push" EGR up to the intake manifold. Today, you'll often see a VG turbine used for that same effect, although the throttle is more versatile and less limited.
Loved the vid! Could you shed some light on why my Volkswagen car does have a little engine brake when I flip my automatic into the manual part of the dsg gearbox?
There are a lot of truck drivers who use the jake brake as a weapon against people who live on lakes, they go really fast and then jake brake for about an 8th of a mile while going by our lake, just to make as much noise as possible. The difference between cowboy's boots and a truck drivers' boots, $hit on a cowboy's boots is on the outside.
Many years ago the exhaust connector just after the header pipe came off resulting in a very loud C16 cat engine, when I used the Jake brake OMG it was crazy loud. That was the greatest day of my 30 yrs driving a truck, driving past kids walking home from school and using the Jake as I passed them set them in a instant panic dropping the books and running in terror from the unbelievable sound. I remember taking the engine all the way to redline and braking as I drove through the short tunnel in my town creating the most awesome terrifying insanity loud Jake exhaust sound Imaginable. Was awesome!!! Good times.
I live in an apartment that's 20 feet from a downhill road where trucks drive and there's nothing worse than being woken up constantly at all hours of the night to this sound. Waking up in a panic not even being able to hear myself think
Actually small diesels have plenty of engine braking by expending energy compressing extremely lean mixture (newer engines can cut off fuel injection completely). And since petrol engine throttle body cuts air intake, in comparison diesels have even better braking. Checked many times in practice.
Question. Are you losing fuel in that compression cycle? Since the compression is released at the top of the compression stroke is the sound of the compression braking caused because the ignition detonation is released directly into the exhaust system? Thanks
Some of the city buses here in the 90s had jake brakes i think, but heavily silenced. There were a sound from them that were very similar to jake brake. There are also other solutions, like retarder brakes that acts on the axel to the wheels
When I was a kid we did a lot of camping up in Siskiyou County, Mount Shasta, Lake Siskiyou, McCloud River, take a ride out to Burney Falls just beautiful country. One of my fondest memories is sitting around the campfire in the late afternoon telling jokes/stories/lies and hearing the logging trucks rolling down off the mountain Jake Brakes blasting,
The best and most laugh inducing way to describe a four stroke engine cycle is SSBB or Suck, Squeeze, Bang, Blow. Never fails get a snigger out of at least one person in the room.😁
Back in the JB Hunt, and a few other companies, didn't have Jakes on their engines. We would see them in the litter box, with their brakes smoking, nearly every day. For some reason they thought all of us log truck drivers in the Cascades, were insane. They could be right but, gravity is free, and brake shoes cost money.
I had a functional Jake Brake installed on my 2 stroke dirt bike. I used the bike for enduros, which is like rally where one can encounter weird and wild terrain.
Probably because you drive a car with an automatic transmission. Engine braking is a lot more noticible at higher rpm. An automatic car keeps rpms low resulting in less engine braking
@@derekl3521 I mean I've done it on stick shifts and I've pulled the automatic shifter down into the 1 and 2 position and the only vehicle I've had that had even a passable engine brake was the 5.4 because it was fairly undersquare.
@@wizard_of_poz4413 Drive a manual with a throttle cable and you will fell the engine braking when you let off of at high rpm, if you have an drive by wire as most cars have been since the 90s then you won't feel it as the throttle isn't fully closing like it would with a throttle cable when letting off. And you will barely feel engine braking through any automatic transmission just because the torque converter clutch turns off with braking unless you got a controller or tune. If you can find an old gas car or truck with a manual trans you'll see what I mean when you let off the throttle at high rpms while in gear but be careful as the car becomes hard to control when letting off abruptly. Electric throttle cars don't let you do that so it feels like they have no braking, some guys swap to a throttle cable for more control over the throttle for driving and braking.
I do know that jakes are loud because by owning a 379 flat top pete with 425 cat with 8" pipe it will rattle windows and is even loud inside the cab of the truck.. I suffer from hearing loss due to the constant exhaust noise of the truck because the pipes are just behind both doors and driving for 8-10hrs for over 25yrs has caused that but wouldn't change it because I enjoyed driving I'm retired now but loved every mile I drove
The Jake is a life saver. my 500hp Detroit made 547hp in jake mode. I could put it in 10 and cruise down I-17 at a perfect 75mph and neve touch the brakes
As one of those engineers that developed Jake or Jacobs brakes for different engines, I would like to add the need to cool the fuel injector tips when using the "Jake". We have come a long way to provide effective braking without the noise, so some of the "use of engine brake" restrictions aren't as necessary as before. ...If a driver uses a Jake, but nobody uses it, is that against the law??? Although the IndiCom2 may not show a ton of INDICATED braking from a diesel engine, there are still a lot of parasitic losses to make engine braking effective, even without a Jake. One example is a Horton clutched fan producing 84hp of engine "braking" at redline. Exhaust brakes from a throttle valve or a VNT are bad ideas, due to camshaft damage due to no follow conditions and up to 5 exhaust valve bounce events. ...And then there are the aquatarders. Those are amazing. I have nearly died a few times on I70 when testing various engine brakes. Runaway lanes were not available for me. The uniformed say that engineers are not that smart or don't have their CDLs. There are some smart engineers out there. You can see us going back and forth on I70 and all over Denver. Look for the INCA cables...
When I drove bus, the city buses had retarders (painfully effective) and the road buses had Jake’s, with wildly varying effect, the Detroit 60’s that usually were quite formidable, and the ISX 13’s which could often hardly be bothered. Strange how much variation in use they can have.
Great point. You had good experiences that few OTR drivers had a chance to get with the retarders. We easily had the opportunity to "outclass" the competition with a terribly effective compression brake. Advanced timing that would burn fuel on the compression stroke was so effective ...so effective that we could make the drive axle(s) unstable. Stability control (or the lack of stability control) put a limit on how effective we could make a Jake. That was more restrictive than meeting noise requirements. This ain't the 90's anymore. The passenger bus drivers get some pretty cool technology that a normal driver may never see. It sounds crazy, but the bus engines were sooooo much more difficult to design for. A bus version of a diesel engine is so much more intense. The on-off-idle cycles of a bus destroy an otherwise normal diesel engine ...especially in mountain cities. ...And then there are the experiences of being hickacked in Columbia or Mexico while validating the bus engines. I lost 4 close friends that were taken hostage. A close female engineer had something even worse happen to her when validating a truck in South Africa. This work is dangerous. Truck drivers are 2X more likely to die on the job, compared to cops. Bus drivers have it pretty tough.
I love that YT has been around long enough that any random thoughts I have like how Jake Breaks work I know someone has made a video about it. Probably lots of people making lots of videos about it. 😂
Funny, I have never heard of a "jake brake"..🤔 In Sweden we use exhaust brakes, that just shuts down the exhaust flow from the engine and let the engine just compress it's own exhaust over and over again. Very effective brakes and it's controlled by a big valve driven by a aircylinder on the exhaust pipe, and when you touch the brake pedal it activates or you can activate it with a button, but it shuts down below 1100rpm..
The video at 4:02 completely misrepresents how the compression brake consumes energy. It is understandable why so many commenters don't grasp the concept. When air pressure is increased, it consumes energy, and it's temperature rises. When air pressure is reduced, it dissipates energy, and it's temperature drops. A coasting diesel engine will inhale air, compress and heat it, then that heated and compressed air will push the piston back down. As the piston goes back down, the pressure and temperature of the air in the cylinder will drop, returning nearly all of the energy back to the piston. It's similar to bouncing on a spring, it keeps returning the energy. This is why the air flowing through a diesel engine doesn't create much retarding force while coasting under closed throttle. The video incorrectly shows the exhaust valve opening as soon as the piston starts to rise, expelling the fresh air through the entire upstroke. With the open exhaust valve venting, the air in the video never has a chance to become compressed during the compression stroke, so a negligible amount of energy would be consumed through compression. In reality, both valves stay closed as the piston rises on the compression stroke, and energy is transferred from the piston into heat and pressure of the air through compression. Then the exhaust valve opens when the piston is near the top (much later than shown in the video) expelling the compressed and heated air before it has a chance to push the piston back down, preventing that energy from being transferred back into the piston. The distance the exhaust valve opens, and the duration of the opening cycle, is very small compared to the way the valve acts on the regular exhaust stroke. When the piston is almost done rising, and under high compression, a very brief and tiny exhaust valve opening is all that's needed to let the heated air escape before it has a chance to return that heat and pressure back to the piston. Excess kinetic energy (in the form of speed) and excess potential energy (in the form of elevation) is normally absorbed by converting it into heat by the foundation brakes through friction, and then dissipating that heat to the atmosphere. In order for a compression brake to share some of the retarding force, it must have a way to gather and dissipate heat. The compression brake puts heat into the atmosphere by capturing the heat of the compression stroke, and immediately routing it into the exhaust system. Some of the heat of compression is absorbed by the engine block and cylinder head, transferred to the coolant, and then dissipated to the atmosphere by the radiator. *The video never shows how the engine gathers the energy through compression.* The video also doesn't mention that the retarding force provided by a diesel compression brake is proportional to the RPM of the engine. The faster a diesel engine is turning, the more cycles each cylinder goes through in a given amount of time. The more air that can be inhaled, the more air that can be compressed, the more heat that can be absorbed and dissipated, and therefore the greater the retarding force. The video also says a gasoline engine provides more retarding force because it uses a throttle body. This is a misleading statement. The air-to-fuel ratio in a gasoline engine needs to stay within a fairly narrow range. A gasoline engine uses the least amount of gasoline while at idle. A tiny amount of air is allowed to pass through a gasoline engine at idle, the rest is blocked by an air valve. As more throttle increases fuel flow, the air valve will partially open to allow more air to enter the engine, keeping the air-to-fuel ratio nearly constant. At full throttle, the air valve will be completely open. A compression brake similar to what is used on a diesel engine would be ineffective on a gasoline engine. At closed throttle, very little air flows through a gasoline engine, so there would be very little air available to compress and absorb energy. Some comments suggest putting an air valve on the intake of a diesel engine to provide retarding force. If that would be effective, then everybody would do it that way, as it would be very inexpensive to do. But restricting intake air offers almost no retarding force. It takes much more energy to create high pressure than it does to create vacuum in a small space in a fraction of a second.
I can't agree that diesels don't have any engine braking without an exhaust brake. I use engine braking all the time in my manual transmission 5.9 cummins. The engine braking come from all of that diesel compression ratio. It's not like having an exhaust brake but trust me, its there and I have used it to slow down trailers for years now.
Hello!! I have a peterbilt 335 with the paccar x6 engine with engine brake, my question is my transmission sometimes fails and the scanner showed low voltage but we couldn't find the problem, whenever the transmission fails the jake brake doesn't work either. Have you had any experience like that?
Good explanation, but -- on the question of why Jake Brakes aren't need on diesel cars -- I would add something. In cars, you can pump the brakes for downhill slowing, which tends to mitigate brake heating. In a truck with air brakes, every time you take your foot off the brake pedal, you vent some of your compressed air to the atmosphere, and if you pump the brakes enough (called "fanning"), you'll run out of compressed air.
We motor home drivers are mostly amateurs about our machines, and we frequently are towing a car behind our coach. Fifth wheel style RV trailers have another different set of problems. It would be interesting to see an overview of the various brake systems employed by RV. My RV, for example, is a 40 foot coach, towing a Chevy SUV, with an added braking system for the towed car, brand name Air Force One. It works great, but don't ask me to explain how it works! And the coach has an electric switch to engage "engine braking," same story.
I'm sure they might come in handy in extreme situations, but drivers around here - a sparsely populated rural area - just LOVE to use them as they go by. No reason - we're on a gentle slope, not a hill, no turns... just being annoying because they can.
I drive a 2021 Peterbilt 567 with a Cummins X15 (2017 X3) with an exhaust brake instead of a Jake brake. Our mechanic says most all new trucks have exhaust brakes instead of Jake brakes. The decibel difference between full engine brake and full throttle is nearly indistinguishable. If I had to choose one I would say that the exhaust brake is slightly quieter. Funny part is the exhaust brake is also made by Jacobs. So, by the same naming convention you can also call it a Jake brake :-)
No , jason the new isx-x15 have a jake brake -(engine brake) but with all the particulate filter they are more muffled down you don't hear the normal noise & yes the variable geometry turbo does restrict the exhaust
Is one potential downside of using a Jake Brake increased wear on the valves? I have to imagine having that exhaust valve pushing into the highly compressed air when the piston is at TDC isn’t great for the valve assembly.
If you guys enjoyed the video, please SMASH THAT LIKE BUTTON. It helps the channel out a huge amount and helps TH-cam put the video in front of more people. Thanks for watching 😬
Diesels do so have engine braking. more engine braking than gasoline engines; though much more still with the Jake brake, which is useful when running as much as 250 lbs per horsepower.
...and now for the skill-testing question:
_Why do they call it a "Jake" brake?_ 🤪
Ummmm, i got a BIG hammer smashed the like button...now i can't watch anymore videos on this phone/device...😬 🤭 oops
@@MickPsyphon because Jacob’s is the name of the company that makes it. There are other brands, Blue Ox, Williams, although those names are probably relics of the past. There are exhaust brakes, essentially closing the exhaust off. And there are engine brakes, that basically turn the engine into an air compressor.
pumpkin time
Studies have proven that the sound of a Jake Brake is significantly quieter then the sounds of a truck coming through your house or car! I live in the mountains, and love hearing trucks on the Jake!
Well of course it’s quieter then the sound of a truck coming through your house well or at least i would hope
I’m just joking dude I know what you mean
I like to hear when the driver has his foot in it and we see the burning coal, and the jake brake sounds like the laughter of children to me.
#1 comment lol amen!!
Used to be a truck driver and I still like hearing them also
Listen officer…. I can do it slow or I can do it quiet…. You can’t have both… you pick… I’ll drive the truck… you write the tickets🤙🤙
Growing up, my dad owned a grading company and at his peak he had 25 Mack trucks with belly dump trailers and 6 end dump trucks, all with Cat engines. Sometimes on days when I was off school, I’d ride around with the different drivers, or sit in the cab of a bulldozer with the operator. Sometimes they’d let me drive a big twin engine 627 Cat scraper or 953 front end loader or some other pieces while sitting on the lap of the operator. By the time I was 14, I was pulling those big Mack’s into the lube bay at the shop, doing oil changes and greasing them under supervision of one of the mechanics. I loved the sound of the Jake’s coming on, man. That quick little clip brought back many fond memories.
We had a service manager who would always pull the wire connectors OFF behind the dash. Shut of MACK engine brake. I would carry a wrench to pull off the Dash plate and hook the wire back up. If I drove the MACK dump that day.
The Kingdom of God is at Hand
John 3:16
King James Version
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
I'm a trucker and my brother was asking me what was that loud sound on trucks. Not being a mechanic myself, I only knew it all happened in the engine, so I'm sharing this with him so he can understand. He has worked on gasoline engines, and he's a Master Technician This is a perfect video explanation for me, and now, for him
Thanks!
I’ve lived close to a highway for over a decade and there is nothing better than hearing a fully loaded, pre-emissions log truck hammering on the jakes.
And you want everyone to hear that sound you love whether they want to or not.
Freedumb!
@@andywomack3414 ~
Andy's pisst off and we're going to hear it also.
@@A.R.77 I don't like having to pause conversation or otherwise adjust my life due to some juvenile driver hammering their jakes on the flat highway a few hundred feet from where I live. And I feel even more ire toward the idiots who tune their puny automotive Diesels to maximize noise and smoke. And there are those masculinity-challenged men children who full throttle their pretend race cars all the time just to make some sort of stupid point about their man-hood.
@@andywomack3414 ~
"...ire toward the idiots who tune their puny automotive Diesels to maximize noise and smoke."
Well, we both agree on that one.
Worst noise ever. Especially when your local truckers do it to piss you off at 4am and they ignore the “No Jake” signs for over 15km. Idiots.
Jake brakes. Designed by Cummins founder Clessie Cummins and was about the only thing he was able to take with him when he lost his company.
After loosing the company, he knew his financial salvation was to be the engine brake, unfortunately, he didn't have the money to build them. He went everywhere trying to come up with financing to make it happen. Finally he approached Arthur Jacobs of Jacobs drill chucks, who was thrilled by Cummins invention. He promised to bankroll the operation....one condition being his name would be front and center in all advertising and communications .hence 'Jacobs engine Brake'....or 'Jake Brake' for short
what a story, nice
Nice
Good, Cumming Brake wouldn't have been so successful
@@bioemilianowould be helpful though 😂😉
@@bioemiliano"gotta use them kum brakes"
I'm too excited that i found people who love the sound of Jake Brakes as much as I do.
The Peterbilt 🤤😍🤯😘
Music to my ears
Engine braking is fundamentally linked with compression ratio. In Europe we can also compare this pretty easily since we often drive manual transmissions and petrol, as well as diesel cars. A diesel has a lot more engine brake compared to a petrol engine of similar size. Jake brakes, exhaust gas brakes, retarders, etc. are used only on trucks since the available engine brake would not be enough for the weak power to weight ration of a fully loaded truck.
Having driven petrol and diesel 4x4's off road, I refuse to own a petrol 4x4 because of the diesels superior engine brake, due to its high compression ratio.
I'm also a truck driver familier with exhaust brakes and engine retarders.
The point of an exhaust brake is to block air flowing out and thus increase the engines compression ratio.
These systems help a lot when you are in the WRONG GEAR.
Going down a hill in a high gear causes the transmission to over power the engines compression, hence the auxiliary braking systems to increase that compression.
The compressed air in the compression stage doesn't "spring back" all that efficiently.
Sure, it's not as effective as a Jake brake, but it's still 10x more effective then a petrol engine.
BTW, anyone who thinks a thin air intake butterfly valve is strong enough to slow a couple ton of moving vehicle on its own is an idiot.
There is a lot more physics behind it all.
Yeah. Thought the same thing. My diesel has more engine braking than a comparable gasoline engine. Only problem is that a truck wheigs a lot more and thus is accelerated a lot more downhill. So you can't compare a car, where need to bring the energy of 1.5 tons into heat, to truck where you need to convert the energy of 40 tons into heat.
@@dragonfire3289 did I forget to mention the part about where I drive trucks and auxiliary braking systems are meant to be used when you stuff up and use the wrong gear going down a hill?
Yes, trucks weight more, but they also have larger engines often with much longer bore strokes, have larger boxier aerodynamic profiles, more tires in contact with the ground etc.
All the things that hurt efficiency and fuel economy, actually help slow down a truck.
Yes they take longer to slow down and yes auxiliary braking systems help a lot, but with the correct use of the foot brakes and the right gear selection, not a single truck on this planet ACTUALLY needs Jake brakes, exhaust brakes, engine retarders etc.
@@35manning Dummy!You have never driven a fully loaded truck down a mountainous road!--Reality with the real possibility to die is different to a video game!
Same comment here. My 2.2 liter Diesel Rav4 has way better engine braking than my wife's 1.6 Petrol Kia.
I live in the country! Id love to hear that symphony coming through my town! Especially that Kenworth rolling across the screen!
Same
Once place I lived there was a road behind my street, I'd hear trucks used their jakes all the time, always a symphony of various engines, miss that place, loved the sounds.
The sound of that Jake brake is music to my ears.
You explain what a Jake Brake is but don't even give a real world example throughout the video. Kudos my man.
Whaaaaat??? Who wouldn't love that sound??
A straight person with a real personality
I definitely DO want to hear Jake Brakes in my town. I grew up next to a hill on a major highway in Central Pennsylvania and I absolutely loved hearing those Jake Brakes all day and night!
True story: the inventor of the "Jake Brake" was one Clessie Cummins. Yes, THAT Cummins. He couldn't convince the executives at the company he founded to buy his idea, so he sold it to the Jacobs company. Hence the name.
During my short trucking career in the 1980’s I drove an Isuzu truck with an exhaust brake. I loved it. Thanks for the great lesson on braking.
I was litterally watching jake brake videos last night. Love me some loud jakes
A jake brake is a really cool sound and it works when you flick the switch
A Diesel engine provides much more engine braking than a spark ignition engine. Compression of the air with 18:1 Compression ratio generates plenty of heat. All that heat energy results in the vehicle slowing down.
Hell yeah, just try crank starting one of those old farm diesels.
electrical retarders are more effective though. the best is to have both obviously
Thank you ahaha when I heard that I was like wtf ahaha diesels are great for the fact that they engine brake, the Jake’s are just an even better brake so you don’t have to use your service brakes and fade them out on a hill
No diesel has a butterfly in the intake unless you have a jake or some kind of engine retarder they will run right past the governor even in low gear going down a steep hill
Nonsense. I've been driving trucks for 35 years and can tell you that loaded or empty, if you lift off the power there's no noticeable drag at all. Remember that compression pushes the piston back down with the same force.
Current engine brakes involve the turbo creating back pressure. They are not only quieter, they are a lot more effective than the old Jakes. I can take a max weight truck down the Grapevine and only occasionally touch the brakes.
~2:20 I used to work on fighter jets. We had a mneumonic to remember the 4 stages of jet engine operation, which are pretty analagous to 4-stroke engine operation.
"Suck, Squeeze, Bang, Blow" - Intake, compression, combustion, exhaust. This was taught in the official training.
Interesting!
I’ve tried watching videos on how Jake brakes work and never really got a good understanding until this video. Finally I understand Joe they work. Thanks
Thanks for the excellent graphics and explanation. I’m a new CDLClass A, and looking for a dump truck to start out. This was by far the best explanation of how a Jake brake works I’ve seen.
For those that enjoy the twisted history of diesel engines, the story of Clessie and his betrayal by the Miller family (again) led to the formation of the company we know as Jacobs, as in Jake brake. That personal story of the Jake brake is even more interesting than the Jake brake by itself. The betrayal and feud exists to this day, a century later.
And a new twist to this is that Cummins is in the process of purchasing Jacob's vehicles system that manufacture the current Jake brake!
The manufacturing rights were sold to the Jacob's Manufacturing Company, yes the drill chuck company. There was no new company formed
I heard that Jacobs is now split between different new owners, Danaher and Cummins.
Who the fuck is classie?
@@benjaminturpin2749 Clessie Cummins, original founder of the Cummins diesel engine company. One of the biggest researchers into the early development of the diesel engine.
Thank you... big time. From time to time I've tried to find out how a Jake brake works and only found idiot phrases like 'changes the airflow thru the engine to provide braking', as if the audience had no idea what goes on inside an engine.
Your explanation was superb.
Thanks for this informative video! I had heard of Jake brakes and now I know how they work. I have heard the sound of a Jake brake all of my life, and I like the sound of them, as long as they aren't in my neighborhood. Good video, sir!
When a Diesel engine is under no fuel, the engine works to compress the air in the cylinder. If no fuel is added, that compressed air will push back down on the piston making for neutral braking. On a Jake brake with no fuel yes the engine works to compress the air in the cylinder, but the exhaust valve opens near top to expell the compressed air hence their is no air pressure left in the cylinder to push the piston back down again-and you get all the compression strokes working as a brake-usually around 400hp of braking.
400Hp of engine braking only at High RPM with all cylinders actively providing braking effort. Also not all engine brakes pop the exhaust valve open near the top of the compression stroke some will actively partially open the valve at the start of the compression stroke and will remain partially open through nearly the entire compression stroke. The piston has to work against the restriction of the valve and sometimes also and exhaust brake downstream of the turbo. This is done to cut down on noise
@@j.m.5995 The original Jake brakes were activated by the injector-hence they opened the exhaust valve near top dead center and at the highest compression pressure-which made for a noisy Jake Brake. Now most Diesels have a separate lobe on the camshaft to operate the Jake brake making them both more effective and quieter.
@@Tchristman100 Was this on overhead Cam engines? I can see how the injector lobe on a pump injector setup could be rigged up to Piggly back off the mechanism to pop open the exhaust valve as it essentially fires fuel at the same time you would want to activate the exhaust valve. I don't know how they could do this on a injector pump setup but I guess where there's a will there's a way lol cheers to Jacobs and their Engineering whose work has spare many a countless life through out the span of time
@@j.m.5995 On engines with an injection pump (like my Caterpillar 3406B mechanical) the Jake brakes work off cross activation. For instance number 1 cylinder is on compression but number three is on exhaust. So number one gets Jake Brake activation by the exhaust valve activating the Jake brake from cylinder 3 to work one. It works OK-just not very strong.
Since we’re going down the diesel rabbit hole here, you gotta do “run aways”…
That would be interesting. Years ago I went over Donner pass and grapevine almost every night and I saw many trucks in the run off ramp. Always felt bad for those drivers. I'm sure some of them had to change they're drawers after they got stopped
@@alanbrown2666 I think he means the conditions where a mechanical fuel pump keeps adding fuel to an engine that won't shut off
@@zenjon7892
Oh. I probably would have known that if I would have paid more attention to the video. Thank you
can't understand why any one would object to the sound of a jake brake. to me it is like the laughter of children. I actually feel a boost of energy when i hear a jake brake. i guess energy is never lost, acording to issac newton.
This is the best explanation of jakes I’ve seen so far. Big fat thumbs up 👍🏼
I use my jakes all the time big brake saver honestly best thing ever
Greatest view at night: trucks with open stacks, with Jake brakes on, going down "the grapevine " in California in the early 80s. Flames three feet high coming out the stacks.
Used to drive OTR, loved the sound of the Jake Brake especially going down
MT. POCCONO ON MY MAIDEN voyage !
2:15 combustion in an ICE is not an explosion, it is called deflagration which is a controlled flamefront.
Which just sounds like a fancy way of saying Explosion, Megumin would be proud :D
Yep, it's not an explosion, it's a controlled burn. It just happens rather quickly.
That was a pretty good explanation.
Years ago I worked for a major motor coach manufacturer. There were 3 basic types of auxiliary brakes offered. Jacobs brakes, transmission retarders (Allison), and magnetic driveline brakes.
I’ve always heard that sound but never knew what it was. Always thought it was a rad sound so thanks for explaining it!!
I never knew diesels have minimal engine breaking. Always assumed the high compression provided high braking, too. Glad I checked this out.
Compression is only half the story-- the piston expands too, so the net braking effect is very weak.
Nothin stopping airflow. Now what if there was a intake shut off? Honestly idk but with diesel compression idk if it would do harm or not.
I have a exhaust brake on my 2500 Cummins and a 5in unrestricted pipe and when I'm coming home you hear it sounds like a big rig love that sounds... and when I go to the city the sound bouncing off the buildings is great
Do that here in Oregon and you’d be subject to a $2000 fine.
@@SodaAnt7 that's vwhy I don't live in a comie state
I used to live about 400yds from 476 and this was an ever present noise on my property
Had a Jake brake fail on a mountain pass in Colorado. My boss was driving. We were 80,000 lbs. To keep from runaway he kept it low gears and was pumping the brakes. Motor stressed and blew close to the bottom. I imagined what sitting on a bomb would be like. I bounced off the headliner. Speed was OK at this point, let it let run out on the flat & got it pulled over, oil trail behind us.
No cell phones back then. Hitched a ride to a phone & called the agent we rented the tractor from. He wanted to know if we were prepared to pay for the blown motor. I ask him if they would've been prepared to pay for our funerals. They towed another tractor to us & dragged the casualty away. We didn't hear about paying for that motor again.
There's a story on the net about how Clesey Cummins (yes, that Cummins) came to invent the jake brake. He was in California in the 1930's with a truck going down hill and narrowly missed a train when he couldn't stop. Cummins invented the jake, but his own company refused to buy it, so he sold it to Jacobs. Clesey Cummins only worked for Cummins, he didn't own it.
The story i heard from a person that was a personal friend of clesey & tested the engine for clesey . The story is the bankers that financed the engine co would not back the engine brake , because they thought it would comprise the engine & ruin the engine & its reputation . So there you go bankers screwing things up AGAIN!!
Oh the sweet sound of the jake brake send chills through me
Who doesn’t love a Jake brake and who starts looking all around when you hear one to see what kinda old school beautiful rig that’s Jake Breaking lol I do
I love the sound that old trucks make while engine braking. active sound design can probably replicate it but at a tolerable noise volume for newer trucks
im not much of a diesel guy but theres something satisfying about hearing jake brakes. like car guys hearing turbo backfires
Love that sound, I lived next to a highway hill section. It would shake the house, awesome. It would give me enough time to see a decked out rig go buy.
Ngl I had no idea what Jake breaks were I just loved hearing this sound growing up in the woods living off the road. But WOW this happens every second maybe more??? Engines are beautiful
I was wondering how a old-school big cam 4 Cummins gets its valve timing for the jake brake apparently off oil pressure but how does it get the timing ? thanks
It gets the altered timing from the engine brake. When the engine brake is activated by oil pressure the master piston is pushed down on the injector adjusting screw and when it is pushed up adjusting screw pushes up on master piston which pushes the oil on slave piston to push it down & opens the exhaust valve which gives the compression blow down ( that where the noise comes from) & then closes to give a vacuum in the cylinder to give more retardation . ( depends on enging ) . That is the best i can explain with out going to great detail.
If you want to continue this Diesel engine series you could talk more about cylinder head stuff like timing and valve overlap, glow plugs etc
Is it necessary to use them in truck stops or entering them ,especially the trucks with straight through stacks.
In most diesel commercial car (at least as old as 2002 I would say) there is a throttle valve at the intake for the EGR. This throttle is also used for engine breaking
A throttle at the intake can't generate net braking. It just determines the fraction of incoming air that is fresh vs EGR. Either way, the intake will get a given quantity of air and no braking will result.
However, you CAN produce braking by throttling the exhaust and this is often used to "push" EGR up to the intake manifold. Today, you'll often see a VG turbine used for that same effect, although the throttle is more versatile and less limited.
Loved the vid!
Could you shed some light on why my Volkswagen car does have a little engine brake when I flip my automatic into the manual part of the dsg gearbox?
I'm not thin skinned. I love the sound of diesel engine and a jake brake.
Love that Jake brake sound!
There are a lot of truck drivers who use the jake brake as a weapon against people who live on lakes, they go really fast and then jake brake for about an 8th of a mile while going by our lake, just to make as much noise as possible. The difference between cowboy's boots and a truck drivers' boots, $hit on a cowboy's boots is on the outside.
Many years ago the exhaust connector just after the header pipe came off resulting in a very loud C16 cat engine, when I used the Jake brake OMG it was crazy loud. That was the greatest day of my 30 yrs driving a truck, driving past kids walking home from school and using the Jake as I passed them set them in a instant panic dropping the books and running in terror from the unbelievable sound. I remember taking the engine all the way to redline and braking as I drove through the short tunnel in my town creating the most awesome terrifying insanity loud Jake exhaust sound Imaginable. Was awesome!!! Good times.
That sound can be deafening when you are outside right next to it- like those kids were. Always wondered what retards did for fun. Now I know...
absolutely love the sound of jakes
Jake Brakes are really only useful at 11pm when you're bobtailing through a truckstop parking lot. Otherwise, they're worthless
Excellent explanation and narration. Thank you!
I live in an apartment that's 20 feet from a downhill road where trucks drive and there's nothing worse than being woken up constantly at all hours of the night to this sound. Waking up in a panic not even being able to hear myself think
Actually small diesels have plenty of engine braking by expending energy compressing extremely lean mixture (newer engines can cut off fuel injection completely). And since petrol engine throttle body cuts air intake, in comparison diesels have even better braking. Checked many times in practice.
Question. Are you losing fuel in that compression cycle? Since the compression is released at the top of the compression stroke is the sound of the compression braking caused because the ignition detonation is released directly into the exhaust system? Thanks
Some of the city buses here in the 90s had jake brakes i think, but heavily silenced. There were a sound from them that were very similar to jake brake. There are also other solutions, like retarder brakes that acts on the axel to the wheels
Usually buses and european trucks use hydraulic retarders.
I only ran my Jakes when I needed them, but you see drivers bobtailing or between gears when upshifting with the jakes on!!
When I was a kid we did a lot of camping up in Siskiyou County, Mount Shasta, Lake Siskiyou, McCloud River, take a ride out to Burney Falls just beautiful country. One of my fondest memories is sitting around the campfire in the late afternoon telling jokes/stories/lies and hearing the logging trucks rolling down off the mountain Jake Brakes blasting,
The best and most laugh inducing way to describe a four stroke engine cycle is SSBB or Suck, Squeeze, Bang, Blow.
Never fails get a snigger out of at least one person in the room.😁
Back in the JB Hunt, and a few other companies, didn't have Jakes on their engines. We would see them in the litter box, with their brakes smoking, nearly every day. For some reason they thought all of us log truck drivers in the Cascades, were insane. They could be right but, gravity is free, and brake shoes cost money.
One of the most beautiful sounds ever made....Jake Brake
I had a functional Jake Brake installed on my 2 stroke dirt bike. I used the bike for enduros, which is like rally where one can encounter weird and wild terrain.
5:23 what are you talking about? it sounds so good!
So on the pistons downstroke after the compressed air is let out before it’s able to combust does it not create a vacuum?
Ohh shit that’s what slows the motor down
In my experience most gasoline engines produce next to no braking effect either so idk where they come up with that idea
Probably because you drive a car with an automatic transmission. Engine braking is a lot more noticible at higher rpm. An automatic car keeps rpms low resulting in less engine braking
@@derekl3521 I mean I've done it on stick shifts and I've pulled the automatic shifter down into the 1 and 2 position and the only vehicle I've had that had even a passable engine brake was the 5.4 because it was fairly undersquare.
@@wizard_of_poz4413 Drive a manual with a throttle cable and you will fell the engine braking when you let off of at high rpm, if you have an drive by wire as most cars have been since the 90s then you won't feel it as the throttle isn't fully closing like it would with a throttle cable when letting off. And you will barely feel engine braking through any automatic transmission just because the torque converter clutch turns off with braking unless you got a controller or tune. If you can find an old gas car or truck with a manual trans you'll see what I mean when you let off the throttle at high rpms while in gear but be careful as the car becomes hard to control when letting off abruptly. Electric throttle cars don't let you do that so it feels like they have no braking, some guys swap to a throttle cable for more control over the throttle for driving and braking.
I love the Jake brake sound!
Jake brake and the air horns are the only reason I drove Big rig in the 1990's
Thank you for this very informative video.
I’ve always wanted to know this.
I do know that jakes are loud because by owning a 379 flat top pete with 425 cat with 8" pipe it will rattle windows and is even loud inside the cab of the truck.. I suffer from hearing loss due to the constant exhaust noise of the truck because the pipes are just behind both doors and driving for 8-10hrs for over 25yrs has caused that but wouldn't change it because I enjoyed driving I'm retired now but loved every mile I drove
The Jake is a life saver. my 500hp Detroit made 547hp in jake mode. I could put it in 10 and cruise down I-17 at a perfect 75mph and neve touch the brakes
love the sound of loud Jakes!
What makes this brake so loud? I would think the muffler would be able to quiet it down but obviously not.
You are extremely well spoken. 👍
As one of those engineers that developed Jake or Jacobs brakes for different engines, I would like to add the need to cool the fuel injector tips when using the "Jake".
We have come a long way to provide effective braking without the noise, so some of the "use of engine brake" restrictions aren't as necessary as before. ...If a driver uses a Jake, but nobody uses it, is that against the law???
Although the IndiCom2 may not show a ton of INDICATED braking from a diesel engine, there are still a lot of parasitic losses to make engine braking effective, even without a Jake. One example is a Horton clutched fan producing 84hp of engine "braking" at redline.
Exhaust brakes from a throttle valve or a VNT are bad ideas, due to camshaft damage due to no follow conditions and up to 5 exhaust valve bounce events.
...And then there are the aquatarders. Those are amazing.
I have nearly died a few times on I70 when testing various engine brakes. Runaway lanes were not available for me. The uniformed say that engineers are not that smart or don't have their CDLs. There are some smart engineers out there. You can see us going back and forth on I70 and all over Denver. Look for the INCA cables...
Did you ever do any testing on Mack's Dynatard system or Caterpillars brakesaver? Not much info about them online anymore
I did not.
When I drove bus, the city buses had retarders (painfully effective) and the road buses had Jake’s, with wildly varying effect, the Detroit 60’s that usually were quite formidable, and the ISX 13’s which could often hardly be bothered. Strange how much variation in use they can have.
Great point. You had good experiences that few OTR drivers had a chance to get with the retarders.
We easily had the opportunity to "outclass" the competition with a terribly effective compression brake. Advanced timing that would burn fuel on the compression stroke was so effective ...so effective that we could make the drive axle(s) unstable. Stability control (or the lack of stability control) put a limit on how effective we could make a Jake. That was more restrictive than meeting noise requirements. This ain't the 90's anymore.
The passenger bus drivers get some pretty cool technology that a normal driver may never see. It sounds crazy, but the bus engines were sooooo much more difficult to design for. A bus version of a diesel engine is so much more intense. The on-off-idle cycles of a bus destroy an otherwise normal diesel engine ...especially in mountain cities. ...And then there are the experiences of being hickacked in Columbia or Mexico while validating the bus engines. I lost 4 close friends that were taken hostage. A close female engineer had something even worse happen to her when validating a truck in South Africa. This work is dangerous. Truck drivers are 2X more likely to die on the job, compared to cops. Bus drivers have it pretty tough.
Ok, great explanation. Now, how is the exhaust valve timing changed?
I used to live near a highway when I was a kid... I miss this sound so much.
I love that YT has been around long enough that any random thoughts I have like how Jake Breaks work I know someone has made a video about it. Probably lots of people making lots of videos about it. 😂
Funny, I have never heard of a "jake brake"..🤔 In Sweden we use exhaust brakes, that just shuts down the exhaust flow from the engine and let the engine just compress it's own exhaust over and over again. Very effective brakes and it's controlled by a big valve driven by a aircylinder on the exhaust pipe, and when you touch the brake pedal it activates or you can activate it with a button, but it shuts down below 1100rpm..
The video at 4:02 completely misrepresents how the compression brake consumes energy. It is understandable why so many commenters don't grasp the concept.
When air pressure is increased, it consumes energy, and it's temperature rises. When air pressure is reduced, it dissipates energy, and it's temperature drops. A coasting diesel engine will inhale air, compress and heat it, then that heated and compressed air will push the piston back down. As the piston goes back down, the pressure and temperature of the air in the cylinder will drop, returning nearly all of the energy back to the piston. It's similar to bouncing on a spring, it keeps returning the energy. This is why the air flowing through a diesel engine doesn't create much retarding force while coasting under closed throttle.
The video incorrectly shows the exhaust valve opening as soon as the piston starts to rise, expelling the fresh air through the entire upstroke. With the open exhaust valve venting, the air in the video never has a chance to become compressed during the compression stroke, so a negligible amount of energy would be consumed through compression.
In reality, both valves stay closed as the piston rises on the compression stroke, and energy is transferred from the piston into heat and pressure of the air through compression. Then the exhaust valve opens when the piston is near the top (much later than shown in the video) expelling the compressed and heated air before it has a chance to push the piston back down, preventing that energy from being transferred back into the piston. The distance the exhaust valve opens, and the duration of the opening cycle, is very small compared to the way the valve acts on the regular exhaust stroke. When the piston is almost done rising, and under high compression, a very brief and tiny exhaust valve opening is all that's needed to let the heated air escape before it has a chance to return that heat and pressure back to the piston.
Excess kinetic energy (in the form of speed) and excess potential energy (in the form of elevation) is normally absorbed by converting it into heat by the foundation brakes through friction, and then dissipating that heat to the atmosphere. In order for a compression brake to share some of the retarding force, it must have a way to gather and dissipate heat. The compression brake puts heat into the atmosphere by capturing the heat of the compression stroke, and immediately routing it into the exhaust system. Some of the heat of compression is absorbed by the engine block and cylinder head, transferred to the coolant, and then dissipated to the atmosphere by the radiator.
*The video never shows how the engine gathers the energy through compression.*
The video also doesn't mention that the retarding force provided by a diesel compression brake is proportional to the RPM of the engine. The faster a diesel engine is turning, the more cycles each cylinder goes through in a given amount of time. The more air that can be inhaled, the more air that can be compressed, the more heat that can be absorbed and dissipated, and therefore the greater the retarding force.
The video also says a gasoline engine provides more retarding force because it uses a throttle body. This is a misleading statement. The air-to-fuel ratio in a gasoline engine needs to stay within a fairly narrow range. A gasoline engine uses the least amount of gasoline while at idle. A tiny amount of air is allowed to pass through a gasoline engine at idle, the rest is blocked by an air valve. As more throttle increases fuel flow, the air valve will partially open to allow more air to enter the engine, keeping the air-to-fuel ratio nearly constant. At full throttle, the air valve will be completely open.
A compression brake similar to what is used on a diesel engine would be ineffective on a gasoline engine. At closed throttle, very little air flows through a gasoline engine, so there would be very little air available to compress and absorb energy.
Some comments suggest putting an air valve on the intake of a diesel engine to provide retarding force. If that would be effective, then everybody would do it that way, as it would be very inexpensive to do. But restricting intake air offers almost no retarding force. It takes much more energy to create high pressure than it does to create vacuum in a small space in a fraction of a second.
Pretty awesome! I got to work as an applications engineer in their plant in Connecticut!
I can't agree that diesels don't have any engine braking without an exhaust brake. I use engine braking all the time in my manual transmission 5.9 cummins. The engine braking come from all of that diesel compression ratio. It's not like having an exhaust brake but trust me, its there and I have used it to slow down trailers for years now.
Agreed but people complaining
about Jake's but there important
Jake brakes are the favourite toy of cowboys driving through towns
Gotta love the sound of the Jake!!!
Can you do an explanation of the mack version of braking,because it dont work half as well?
Hello!! I have a peterbilt 335 with the paccar x6 engine with engine brake, my question is my transmission sometimes fails and the scanner showed low voltage but we couldn't find the problem, whenever the transmission fails the jake brake doesn't work either. Have you had any experience like that?
A lot of towns have ordinances outlawing engine braking.
Good explanation, but -- on the question of why Jake Brakes aren't need on diesel cars -- I would add something. In cars, you can pump the brakes for downhill slowing, which tends to mitigate brake heating. In a truck with air brakes, every time you take your foot off the brake pedal, you vent some of your compressed air to the atmosphere, and if you pump the brakes enough (called "fanning"), you'll run out of compressed air.
You can always tell a rookie trucker, they are always the one that leaves the Jake brake on while driving through Cities, towns and Metro areas 🤪
Or he's just a menace to society 😎
I love the sound of the Jake Brake.
How does it effect engine and transmission 'life. these are more expensive than brake pads?
We motor home drivers are mostly amateurs about our machines, and we frequently are towing a car behind our coach. Fifth wheel style RV trailers have another different set of problems. It would be interesting to see an overview of the various brake systems employed by RV. My RV, for example, is a 40 foot coach, towing a Chevy SUV, with an added braking system for the towed car, brand name Air Force One. It works great, but don't ask me to explain how it works! And the coach has an electric switch to engage "engine braking," same story.
I'm sure they might come in handy in extreme situations, but drivers around here - a sparsely populated rural area - just LOVE to use them as they go by. No reason - we're on a gentle slope, not a hill, no turns... just being annoying because they can.
I drive a 2021 Peterbilt 567 with a Cummins X15 (2017 X3) with an exhaust brake instead of a Jake brake. Our mechanic says most all new trucks have exhaust brakes instead of Jake brakes. The decibel difference between full engine brake and full throttle is nearly indistinguishable. If I had to choose one I would say that the exhaust brake is slightly quieter. Funny part is the exhaust brake is also made by Jacobs. So, by the same naming convention you can also call it a Jake brake :-)
No , jason the new isx-x15 have a jake brake -(engine brake) but with all the particulate filter they are more muffled down you don't hear the normal noise & yes the variable geometry turbo does restrict the exhaust
Is one potential downside of using a Jake Brake increased wear on the valves? I have to imagine having that exhaust valve pushing into the highly compressed air when the piston is at TDC isn’t great for the valve assembly.
Wear is very minimal.