Exhaust Brake on an M35A2

[rustystud]

Modern diesel engine DO put unburnt fuel directly into the exhaust, be it into the pipe just past the outlet of the turbo via separate injector or via 5th injection (dosing) cycle when the exhaust valve is open and evacuating the cylinder of the burnt gasses, That is how the catalyst starts the reaction needed to get the DPF inlet to the required temp to turn the soot to ash, don't care if it is Cat, Cummins, Navistar, Volvo, Mack, Isusu, Deere, Ford, VW, they ALL hydrocarbon dose the aftertreatment to start the process.

The above switch completes a circuit when the throttle is released (at idle position) that allows DC voltage to energize the EB solenoids, it doesn't shut fuel off, drive by wire engines use the TPS to send that signal.

View attachment Scan0205.pdfView attachment Scan0206.pdf

Again there is a grain of truth to your statement, but the reality is something different. The system your describing is the "Lean NOx catalyst" system. It is only used on a very few engines. The most common is the "SCR" system which uses the "urea" solution. That is the stuff you must add to almost every modern diesel engine on the road today. Your comment about the switch is also misleading. Of course the engines ECM controls the fuel but it receives the signal to shut-off from the Jake brake. So I have a question for you Mr. Wagner. Have you ever actually worked on a Jake brake system ? I can assure you I have, plenty of times. So again I'm speaking from personal experience here. If you can provide technical proof that I'm full of "Sh!t" then I will graciously admit I'm wrong to the whole Steel Soldiers community. As they say "the ball is in your court" .

 

[Floridianson]

Don't think anyone is attacking your name. I will say on the picture you posted on my M920 and M915 where it says fuel pump switch maybe it should say PT throttle linkage micro switch for the older stuff we are working on. Though the PT is a fuel pump it might not be clear to someone that does not know and they might think there is a different fuel pump that cuts off the fuel. My PT just returns to idle and switch is closed on my older model engines.

 

[WillWagner]

No, never worked on one, Just a bumpkin behind a keyboard. I just read alot

 

[cbrTodd]

Again there is a grain of truth to your statement, but the reality is something different. The system your describing is the "Lean NOx catalyst" system...

I realize that I have no dog in this fight (and that this derails this thread a bit further off topic), and I mean no disrespect to anyone involved, but WillWagner is correct in his statement that modern diesels dose hydrocarbons into the exhaust stream for DPF regeneration purposes. In circumstances where the exhaust gases aren't hot enough to start the oxidation reaction in the DOC and DPF, hydrocarbons are injected into the exhaust stream to increase the temperature. It is most commonly used for stationary regen purposes for the DPF.

As WillWagner said, sometimes this is done with an external hydrocarbon doser at the outlet of the turbine, and sometimes it is done by pulsing the injectors during the exhaust stroke to send unburnt hydrocarbons downstream to the DOC. On the engines that I have been involved with as a product development engineer, 11-15 liter sized engines used an external doser after the turbine, and 6-9 liter sized engines used in-cylinder methods. My point is that this strategy is critical to EPA 2007, EPA 2010, and EPA 2013 certified engines (and newer ones, but I have not worked specifically with those as I have the ones mentioned). This is not an antiquated technology - it's still in use on new product being produced today.

Take a look through the linked Peterbilt owner's manual if you'd like.

http://www.peterbilt.com/resources/...ftertreatment Systems - Operator's Manual.pdf

 

[red]

I realize that I have no dog in this fight (and that this derails this thread a bit further off topic), and I mean no disrespect to anyone involved, but WillWagner is correct in his statement that modern diesels dose hydrocarbons into the exhaust stream for DPF regeneration purposes. In circumstances where the exhaust gases aren't hot enough to start the oxidation reaction in the DOC and DPF, hydrocarbons are injected into the exhaust stream to increase the temperature. It is most commonly used for stationary regen purposes for the DPF.

As WillWagner said, sometimes this is done with an external hydrocarbon doser at the outlet of the turbine, and sometimes it is done by pulsing the injectors during the exhaust stroke to send unburnt hydrocarbons downstream to the DOC. On the engines that I have been involved with as a product development engineer, 11-15 liter sized engines used an external doser after the turbine, and 6-9 liter sized engines used in-cylinder methods. My point is that this strategy is critical to EPA 2007, EPA 2010, and EPA 2013 certified engines (and newer ones, but I have not worked specifically with those as I have the ones mentioned). This is not an antiquated technology - it's still in use on new product being produced today.

Take a look through the linked Peterbilt owner's manual if you'd like.

View attachment 686676 http://www.peterbilt.com/resources/...ftertreatment Systems - Operator's Manual.pdf

Although technically correct on some models, that's not what the original disagreement was about. It was a redirect. Disagreement was about fuel being shut off to the cylinders while the Jake brakes are active. Which is correct, fuel is not injected into the cylinders during Jake brake operation. There's no temperature concerns for the injectors at that time because it's "relatively cool" in the cylinder without the fuel to be ignited and no lubrication concerns because the pump is still flowing fuel (still lubricated) but the injectors are not moving (no lube needed at that time), so the fuel is sent out through the return line.

As for a butterfly valve exhaust brake on the multifuel, it's been proven to work fine. That setup has been used for decades on other mechanical injected engines with no ill effects to the engine. The idle amount of fuel being injected into the cylinders when using a exhaust brake is still compressed and ignited, the reason why it was never as effective as Jakes on mechanical engines. With newer electronic fuel injection the injectors can be programmed not to open which keeps the fuel flowing through the pump/rail so the pump stays lubricated while the fuel stays out of the cylinder.

 

[rustystud]

Although technically correct on some models, that's not what the original disagreement was about. It was a redirect. Disagreement was about fuel being shut off to the cylinders while the Jake brakes are active. Which is correct, fuel is not injected into the cylinders during Jake brake operation. There's no temperature concerns for the injectors at that time because it's "relatively cool" in the cylinder without the fuel to be ignited and no lubrication concerns because the pump is still flowing fuel (still lubricated) but the injectors are not moving (no lube needed at that time), so the fuel is sent out through the return line.

As for a butterfly valve exhaust brake on the multifuel, it's been proven to work fine. That setup has been used for decades on other mechanical injected engines with no ill effects to the engine. The idle amount of fuel being injected into the cylinders when using a exhaust brake is still compressed and ignited, the reason why it was never as effective as Jakes on mechanical engines. With newer electronic fuel injection the injectors can be programmed not to open which keeps the fuel flowing through the pump/rail so the pump stays lubricated while the fuel stays out of the cylinder.

YES !!! Finally someone see's what I'm saying. I did call "Cummins Northwest" today and my friend said to call the Tech department at 800-286-6467 . They also verified what I have been saying (in fact they said why in the world would you add fuel when your trying to "slow down" the truck ? ) but to get an actual document I need a specific engine serial number so they can print it out. So does anyone have a Cummins engine that they can post the serial number here ? It must have the "engine brake" on it.

 

[rustystud]

I realize that I have no dog in this fight (and that this derails this thread a bit further off topic), and I mean no disrespect to anyone involved, but WillWagner is correct in his statement that modern diesels dose hydrocarbons into the exhaust stream for DPF regeneration purposes. In circumstances where the exhaust gases aren't hot enough to start the oxidation reaction in the DOC and DPF, hydrocarbons are injected into the exhaust stream to increase the temperature. It is most commonly used for stationary regen purposes for the DPF.

As WillWagner said, sometimes this is done with an external hydrocarbon doser at the outlet of the turbine, and sometimes it is done by pulsing the injectors during the exhaust stroke to send unburnt hydrocarbons downstream to the DOC. On the engines that I have been involved with as a product development engineer, 11-15 liter sized engines used an external doser after the turbine, and 6-9 liter sized engines used in-cylinder methods. My point is that this strategy is critical to EPA 2007, EPA 2010, and EPA 2013 certified engines (and newer ones, but I have not worked specifically with those as I have the ones mentioned). This is not an antiquated technology - it's still in use on new product being produced today.

Take a look through the linked Peterbilt owner's manual if you'd like.

View attachment 686676 http://www.peterbilt.com/resources/...ftertreatment Systems - Operator's Manual.pdf

We are not talking about "Regeneration" . That is a totally separate subject. Also all the Cummins engines with the "common Rail" injection use the "SCR" system. Again I'll post proof of what I'm saying. This is from the Cummins Service Manual.

View attachment Scan0207.pdf

 

[rustystud]

Don't think anyone is attacking your name. I will say on the picture you posted on my M920 and M915 where it says fuel pump switch maybe it should say PT throttle linkage micro switch for the older stuff we are working on. Though the PT is a fuel pump it might not be clear to someone that does not know and they might think there is a different fuel pump that cuts off the fuel. My PT just returns to idle and switch is closed on my older model engines.

Floridianson I know your just trying to keep the peace here and I respect that, as I also respect you and your knowledge of these military vehicles. But I was slandered when I was told I'm spreading false or "FUD" information. Especially coming from a "Moderator" . If it was from some other member that didn't know his A$$ from a hole in the ground I would just set him straight and be done with it. But from a "Moderator" that is something else entirely. I do know Mr. Wagner has knowledge and has helped this community a lot, that is why that comment of his is so egregious. Now I know I will not be receiving any apology over this as that is not Mr. Wagners style. So having proved my point I am done posting here.

 

[doghead]

https://youtu.be/H8OxKx6zKkQ

 

[rustystud]

https://youtu.be/H8OxKx6zKkQ

Really ?!?!

 

[Floridianson]

[QUOTE=red; Disagreement was about fuel being shut off to the cylinders while the Jake brakes are active. Which is correct, fuel is not injected into the cylinders during Jake brake operation.

In the later model computer engines that can control the injectors maybe you should say to keep things correct. Though this thread went down hill fast I learned more about the newer systems. I say lets tar and feather plym49 for asking the question that started the down hill quiet riot.

 

[Jbulach]

..... So having proved my point i am done posting here.

fud

 

[Floridianson]

O crap someone lock this thread.

 

[Jbulach]

O crap someone lock this thread.

Why should another interesting thread be lost, due to sensitive people going off on tangents and throwing tantrums???

Maybe it needs cleaned up a little, but the OP doesn't deserve to have it locked...

 

[red]

Depends on which mechanical engine and model Jake brake. I won't tar and feather someone for asking questions, we all learn somehow. I have a problem with people that won't own up to their mistakes, rather throw out an insult and try to change the conversation which is exactly what lead to this. We get enough of that **** from liberals, no need for it during technical discussions.

 

[Floridianson]

Jake brakes open the exhaust valves just before top dead center allowing all that compressed air to exit out the exhaust. It also stops the fuel. So each time the piston is coming up to top dead center the engine is compressing all that air which requires HP and then just letting it go. It can really bring a heavy loaded trucks speed down fast but it is "loud" !!!
An Exhaust brake is just a flap that partially or almost totally closes off the exhaust from the turbo which causes the engine to slow down. In the newer trucks it also shuts-off the fuel with a signal to the ECM.

Read this again and this is where I feel if Rusty would have said about the jakes that the newer models cut off the fuel. He said the exhaust brake does in the last line not the top line. I had to read the whole thread a couple of times and at first I thought we were just dealing with the motors that are in our older model military trucks. What we most do around here. Then everything switched to the newer stuff and I learned somethings. As I posted our /my older M920 M916 M915 had mechanical PT's and they do not shut off the fuel when jake is used the PT is at idle fuel. Funny how something so simple can cause this mess.
The tar and feather was a joke trying to misdirect the whole thing. Yes we live for questions.

 

[rustystud]

Read this again and this is where I feel if Rusty would have said about the jakes that the newer models cut off the fuel. He said the exhaust brake does in the last line not the top line. I had to read the whole thread a couple of times and at first I thought we were just dealing with the motors that are in our older model military trucks. What we most do around here. Then everything switched to the newer stuff and I learned somethings. As I posted our /my older M920 M916 M915 had mechanical PT's and they do not shut off the fuel when jake is used. Funny how something so simple can cause this mess.
The tar and feather was a joke trying to misdirect the whole thing. Yes we live for questions.

OK, maybe I should have led with the last sentence. I thought it made perfect sense when I wrote it. I do get your joke. It was funny !

 

[Floridianson]

Nothing to worry about and just keep on getting up Greg you and Will have lots to offer. I have to think things through three times before I type and sometimes I still don't get my thoughts right in print.
You guys are the mechanics I got away from trying to keep up with all the new stuff in 1990. I got into real estate and I should have stayed there. Now I have more trucks than brains and just remember some tricks.

 

[Another Ahab]

OK, maybe I should have led with the last sentence. I thought it made perfect sense when I wrote it. I do get your joke. It was funny !

That humor is greatly appreciated!

Because the thread here was starting to get like when the Past, the Present, and the Future all walked into a bar at the same time...

It was getting Tense.

 

[rustystud]

Why should another interesting thread be lost, due to sensitive people going off on tangents and throwing tantrums???

Maybe it needs cleaned up a little, but the OP doesn't deserve to have it locked...

I can only surmise that you don't like me much . The feeling is mutual I'm sure.