Exhaust Brake?

[Capt.Marion]

While I do not know much of anything about Multifuel Diesels in Deuces, Deuces in general, or life, for that matter, I was wondering if anyone had considered rigging up an exhaust brake on their deuce...

I did some googling to educate myself, and was surprised to see that diesels do not have any engine braking abilities (without a jake brake or exhaust brake). That would explain why the diesel tractor does not slow down going down the hill w/o using the brakes! (I love figuring out things, especially the stupid simple ones). I figured it might be supplemental to have something other than the brakes and friction to help slow down your truck, without the apparently large amounts of modifications necessary for a jake brake.

Just curious if anyone had ever wasted a bit of brainpower on this.


-Ken

 

[Recovry4x4]

Read this one for starters. http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=13110
Then read this one for everything you need to know. http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=3465

 

[cranetruck]

......and was surprised to see that diesels do not have any engine braking abilities (without a jake brake or exhaust brake)......

There is always a small amount of engine braking power in the diesel, not much, but you have to keep the engine rpm as high as possible, since there is a multiplier effect. This is why you must keep the road speed low when going downhill. Some long hills have speed limits going down (for trucks) for this reason for those who don't believe.

There are also other "driveline" braking systems, electric and the hydraulic, which is built into the transmission (Allison automatics, for example). The hydraulic is actually more effective than the jake brake and silent to boot. The exhaust brake is least effective, but cost the least...I spent less than $100 on my system, using junk parts.
The exhaust brake also has a side benefit, by closing it off (at idle), the engine warm-up time is reduced.

 

[Trango]

I also put an exhaust brake on my deuce. Granted, I am using a different engine (and I actually have a wastegate in parallel with my Pacbrake to keep backpressure low, a requirement on the 320, but the location is the same.

I haven't written it up, but it is on the stack, just next to the rearview mirror.

 

[saddamsnightmare]

January 27th, 2008.

Dear Capt. Marion:

If you read the -10 operators manual for the M44 series, you will find that the Multifuel engine was and is very sensitive to overspeeding, and the manual specifically states that the engine is not used to hold or slow the truck without watching the rpm's. It also states that one should descend the hill in one gear lower then you came up it, to better control the truck. I rather doubt that a stock multifuel could handle an exhaust brake without ill effects, and from my days in West Virginia, the Jake or engine brake is universally hated by municipalities due to the EXCESSIVE noise. Here in Texas both local towns that I pass through daily forbid the use of an exhaust brake in the town limits, subject to fines. They ain't too fond of the M35's stack bark, but there's little they can do about it as it is grandfathered by it's age. Pity no one has tried a hybrid diesel-electric-battery drive, as one could use the motors for dynamic braking and recharge the batteries at every stop (or at least assist the engine to do so).
The army experimented, I believe, back in the 1960's with a ConDec modified duece with electric motors in each hub and a diesel electric drive as an experiment, and I'm am sure Mr. Doyle will pull that rabbit out of his very large magician's top hat. Food for thought....

Sincerely,

Kyle F. McGrogan
1963 Mercedes Benz Unimog S404.114 (Swiss)
1971 Kaiser Jeep M35A2 Wo/W "Saddam's Nightmare" Vietnam and Desert Storm Veteran Deuce.

 

[Jones]

Another benefit in retarder braking; be it exhaust, drive-line, dynamic braking or in-the-transmission retarders is that it saves on wheel brake heat build-up/fade, wear & tear. And probably most important-- cutting back on the possibility of depleting your air from repeated applications.

 

[oifvet]

O.K. I'm going to have to ask... What is it about diesel engines that they do not, "brake?" Is it something having to do with high compression? This is an area that I'm lacking in knowledge. I understand how a Jacob works. Just stuck on this, "multiplier effect." Thanks in advance for the education, whomever it comes from.

 

[cranetruck]

Okay, very simply, engine braking is a result of resistance to the piston movement.
In a gasoline (ignition) type engine, the throttle resists the "sucktion" of air into the combustion chamber, thus creating an "engine brake" effect. The diesel is always wide open (=has no throttle) and there is very little resisting the piston movement.
By placing a butterfly valve in the exhaust pipe, resistance is created by making it harder for the engine to exhaust. The back pressure created in the exhaust system can be 20 to 50 psi and the higher the rpm, the more times this action takes place (=multiplier effect).
Note: Never use the exhaust brake when engine is powered by fuel, only when it is driven by the rolling force, like going down hill (foot off the pedal).
The braking HP can be calculated based on rpm and exhaust back pressure.

The electric or hydraulic type driveline braking works on a different principle. They both convert the energy absorbed into heat, which must be dissipated. The hydraulic type needs a good transmission fluid cooler, for example.

 

[m-35tom]

you can put a butterfly valve in the intake and have about the same effect as a gas engine, (with a blow off valve) but the multifuel has no valve stem seals. when using a exhaust restricter you should have a switch on the throttle that prevents it actuating except when the ip is at idle setting. was a jake ever made for engines with external ip's?? it simply opens the exhaust valve just after injection takes place so that the compression stroke is wasted.

 

[cranetruck]

you can put a butterfly valve in the intake and have about the same effect as a gas engine.....

Looked in to it one time and don't think it would be as effective (limited by the max vacuum that could be had, one atmosphere? which would translate into 14 psi), but it would provide for a way to shut down a runaway engine.

 

[m139h2otruck]

Not to hi-jack this thread, but I did see a Detroit engine run-away in reverse one day at a jobsite when I was just a kid (35 years!! ago). The trucker jumped the clutch and the engine coughed and rolled backwards and kept running. The emergency butterfly on the intake housing to the blower didn't work because the blower was pushing exhaust out the air filter and just blowing the flapper open. Our mechinic was just as calm as anything and just said in a normal voice "let the clutch out and stall it". The driver was so flustered he tried every trick he could think of except for that. After a few minutes he stalled the truck and restarted it like nothing happened. Great fun when you are 19 and everything is "new".

 

[majortom]

i have duel jakes on my ten ton. really loud, way cool. be very carefull about back pressure after the turbo, the exhast brake can make the turbo stop too fast damaging the thrust bearing.

 

[rivired]

so can we get any input from the more knowledgeable about if a stock multifuel in good working order can handle the pressures ect ect of a common exaust brake?

 

[cranetruck]

I limit the exhaust back pressure to about 35 lb since there are no real guide lines to go by. It gives me about 50 hp of braking power for high RPMs....

 

[reloader64]

I clicked on the links in post #2, and I get the "page not found" thing

Scott

 

[cranetruck]

Try this one:

http://www.steelsoldiers.com/showthread.php?t=3255&highlight=exhaust+brake

 

[Hammer]

I thought we would be limited to #25 of back pressure by our exhaust springs?

 

[cranetruck]

I thought we would be limited to #25 of back pressure by our exhaust springs?

Hmmm...more like 60-70 lb...might check on it again to make sure....

 

[Hammer]

I just remember looking up the kit for our trucks, and it showed 25 lbs. I know that this number is almost always based on the the closed spring pressure on the exhaust valves.
This was one of the reasons I wasn't in TOO big of a hurry to run an exhaust brake.
Any brake would be good, but at only 25#, that will not provide a lot of braking hp.

Now, if we really could run 60 lbs, WOOHOO. It would provide substantially more braking, and would be worth a lot more to me.

 

[cranetruck]

There are lots of numbers out there, need to check the multifuel engine specifically, here is one example:
" An engine brake relies on exhaust back pressure to slow down the truck. An engine brake will not harm the Cummins ISB 5.9L engine. One limitation, however, is that the engine brake must be designed to limit maximum exhaust back pressure to 60 psi or less in order to prevent the other exhaust valves from being forced open by exhaust back pressure. The brake manufacturers have a precise orifice in the plate that covers the exhaust flow to prevent pressure above the 60 psi limit."