Is adding an engine brake an option and how much would it cost?
What year U320? You (should) have a hydraulic transmission retarder. You want to add a compression release engine brake (Jake brake)?
Yes, if you are asking that an engine compression brake can be added to a Cummins M engine it can be done. An expensive engine upgrade plus wiring to the front. Contact your Cummins dealer with your engine serial number.
But, like Chuck, I have to ask WHY?
Once you have a Jake, the question is answered.
Pierce
Pierce,
I am also a big fan of engine compression brakes-- excellent braking HP without adding heat to the transmission.
BUT, not sure I could rationalize adding it to a coach already fit with at transmission retarder.
Heard that same statement about a retarder,sounds almost like your spending $10 to save $5.
Understand that but if the budget allows, it's great. Not just heat to the retarder but added complexity and maintenance down the road. I just leave the Jake on all the time and don't even think about it. But we live in the mountains. Would have the retarder light on all the time here.
Pierce
I see alot of signs in towns saying no engine brake allowed,never saw one for a retarder.
I have no experience with an engine compression brake, but I've read that those with exprience with both prefer the Allison retarder. Any comments from those with experience with both?
Have had "jake" brakes in 3 coaches, two on 2 strokes and one on a Series 60. Compression brakes generally only have 1,2 or 3 stages, unlike the multiple ones on a retarder. Jakes are more dependant on engine speed, but as Pierce says, you can just leave them on all the time and not worry about transmission temps. I made the mistake of putting a resonator on the coach with the series 60, sounded like a machine gun with the jake on.
I've had all three (Pac, Compression, Retarder). The retarder is the best but a two or three speed Jake is pretty sweet. Both? Go for it!
jor
The 11 liter m11 engines displacement limits its jake brake abilities somewhat. My Cummins shops foreman/owner showed me a jake assembly that was off of a crane trucks engine. Used parts seem to be about a CB. Really had considered it as an adjunct in serious down grades to add another reserve method of braking.
So far enough reserve in up to spec brakes and the retarder barely so I understand the interest.
I'm in the market for a 320 and when I get one I have been thinking about adding a Jake brake. I drive in the mountains all the time and with the engine brake I don't have to worry about heat. I like the idea of both for the highway and for town the retarder.
Should have said that we had a retarder on one fire truck with a six speed Allison. With almost 10,000 lbs of water and fuel, it was pretty easy to have the warning light turn on when going out of town on campaign fires. Worked slick around town.
Pierce
I prefer a jake break: I'll jump in and provide my 2 cents on jake brakes - 98% of our fire truck fleet (approx 400 rigs) use a jake brake or a similar engine brake. My own experience of driving fire engines with jakes for 30 years is that they work great, no heat build-up, minimal downtime, and maintenance. While I have less than 4 months driving my FT with a Retarder - I prefer a jake brake.
I find myself having to really match engine speed, trans selection, brake pedal force, and retarder temps on my FT when descending hills to find a comfortable braking speed and the trans can quickly go from 198* to 250* in less than 30 seconds of hard retarder application - making me have to worry about too many inputs and variables to not damage my trans and also be safe. Which lead to distractions when driving.
But I will admit that when my DW drives our FT - I think that the simplicity of having the retarder switch turned on offers greater safety for her not having to fiddle with the jake - but then again she is not doing the mountain driving.
This is only my own opinion based on personal experience.
The disk brakes are somewhat cold blooded especially if the coach has not been driven recently. Rotors I think get surface rust on them. Need to be warmed up and deglazed before they can be relied upon if really needed.
Hence the factories wider adoption of the retarder versus only the 6v92 U300's originally.
Especially as the D2 seems to slowly lose pressure from oil buildup in the valving, at least in my case.
Adjusting the D2 to the max of 130/110 gives much stronger braking. Lessening the need for the retarders input.
The brakes obviously have a certain limit of heat absorption as does the retarder.
As Wolfe mentions downshifting the engine/trans increases the natural ability of a four stroke engine to hold back any vehicle.
Helps. Mixing the retardation and the brakes and keeping the revs up maximizes their abilities.
Driving hard like I am used to doing and living where everywhere out of our area involves hills I tend to be probably closer to the coaches limits.
Trained a lot of customers of the coaches actual limits versus they got concerned(panicked) if the temp gauge moved off its nominal minimum position.
The jake addition I put on similar displacement marquis with 3176 cats made the coach a true up and down interstate grades at 65 at 37,000 pound combined with both heels in front on the drivers seat.
2,4 or 6 cylinder jake panel on the left drivers wall(which was hollow to allow this placement) allowed the driver to control their downhill speed.
The 8,3 can have an exhaust brake if the engine has the correct valve springs which I think all the Foretravels have oem.
Which actually worked fairly well if you kept up the motors revs.
Rocky Mountains and high loads and increased speed users might consider the m11 jake option. I have.
The cat marquis had an optional after delivery customer preference software update available that allowed the jake to work with cruise control.
Like my 97's retarder. Works with the cruise. Marvelous.
If I added a jake it would have to be able to operate separately from the retarder and work on cruise control.
If possible....
Pipe dreams so far but the idea is there
Is this discussion confusing 'engine compression braking' and 'exhaust braking'?
'Jake'obs Company makes both types and both could be called 'engine Jake brakes'
Cities sometimes outlaw engine compression Jake brakes because of the brap brap sound from compressed air being released at the top of the compression stroke.. I don't think cities outlaw exhaust Jake brakes.
How an engine brake works | Jacobs Vehicle Systems (https://www.jacobsvehiclesystems.com/parts-service-support/how-an-engine-brake-works)
Exhaust Brakes | Jacobs Vehicle Systems (https://www.jacobsvehiclesystems.com/technologies/exhaust-brakes)
The original question was one of the above vs 'transmission braking'
An engine brake also known as a Jake break pops a valve open before top dead center on the compression stroke to eliminate the rebound of the compresson created. Where as an exhaust brake works like a potato shoved up the tailpipe. Exhaust brakes are not as efficient as a Jake brake but are cheaper to build and install and don't add excessive noise.
The question was adding an engine brake to a U320 which would have the retarder already installed.
Believe Jacobs Brake Technology filed for a patent on the engine compression brake, to be called a "Jake brake" to differentiate it from the Jacobs exhaust brake. As you say, big difference between "jake brake" and "exhaust brake" even though both are made by Jacobs.
When people ask me how I like our exhaust brake, I tell them "It's not a retarder, and it's not a Jake, but it's better than nothing!"
We've crossed the Rockies 3 times pulling 4000 pounds of towd, and lived to tell about it.
4th gear at 45-50 mph (about 2400 rpm) is the sweet spot for descending a steep grade with our exhaust brake. :thumbsup:
Jacobs invented the Jake Brake many years ago but installed on Detroits and Cummins starting in 1961. Jacobs Vehicle Systems now produces the Jake Brake as well is using their name for an advantage in marketing the exhaust brake that restricts the exhaust system rather than utilizing the compression stroke and then releasing the compressed air near the top of the compression stroke.
https://www.youtube.com/watch?v=HkfjCJClWVA
Our U300 does not make a lot of noise but if we had a resonator on it, it would probably wake the dead. Modern Jake Brakes in the latest trucks do not make any additional noise. Ours just makes the Emmy winning 2 cycle noise if you open the driver's window in a tunnel.
I have to agree with Pibutler in that with the Jake switched on, there is nothing to fiddle with, in fact, I don't notice that it's on. In the taller gears on Interstate downgrades, it keeps the speed about perfect and when the smaller highways are steeper, I just drop a gear and use both the normal engine braking at higher RPM and the Jake as the higher the RPM is, the better it works.
Heading down to Lake Tahoe over Donner Pass on I-80, I shift down to third (four speed) and only have to use the service brakes perhaps three times for just several seconds on the way down. Jacobs did his first trial on what is now I-50 at Lake Tahoe.
Anything that will aid the service brakes to allow a safe grade decent is great but Jakes are my favorite of the bunch.
Pierce
Thanks everyone for your help. I am sorry for not getting back to you so late but I was having a hard time getting on the forum due to username and password. Issue. Any pointers for a newbie driving in the mountains with a retarder?
Be conservative and treat the retarder as a secondary/supplemental aid to the service brakes. Overuse can cause the transmission fluid to overheat and a warning light to come on. Shift the transmission to lower gears to descend grades. The Interstates are not usually that steep but the mountain two lane roads can be steep and with cars behind, you may feel pressure to go faster. Use turnouts and let traffic go past. After a few downgrades, you will feel more confident.
Go easy on retarder operation in the rain and especially snow. Once the rear end comes loose on a downhill, it may not be possible to catch it.
I frequently drove a fire truck with 10,000 lbs of water and diesel. It had drum brakes and the retarder was a welcome addition. We had a six speed Allison so used the transmission and retarder as much as possible to keep the speed down but I did have the big yellow retarder light come on several times when we were in a hurry.
Pierce
We push 7% downhills often: I figure my intended speed before the grade and let the six speed gear down them hit the Pac Brake and toggle on/off as needed. Only have to use the main brakes for pokie RVs w/toads or semis. Works perfect! ^.^d Brett moved the shifting console and mounted the Pac Brake switch below. My hand reaches it without taking my eyes off the road!
When this link first started up I was in the process of buying a U320 and thought a Jake would be nice. Now that I have a U320 I am
looking for a good used Jake so I can install it in the spring. I love the retarder but on the long grades I would have to slow down
and with the Jake I wouldn't, as it won't over heat.
Our coach doesn't have a jake brake, retarder or exhaust bake and it has the 4 speed allison that doesn't lock up until high in 3rd gear so using the engine for added braking is fairly pointless.
We're heading to Hungry Horse Montana to spend the summer so if you hear of a motorhome careening off the side of a mountain and exploding into a giant fireball, you'll know why! Hahaha!
(Hannah & Tyler) already looked into exhaust brakes. (Thread linked below, Reply #64) Didn't have any luck.
94 U280 Pac Brake Switch (https://www.foreforums.com/index.php?topic=35880.msg353107#msg353107)
The secret is to monitor transmission temperature, since the retarder basically turns momentum into HEAT.
On long grades, use the transmission selector to keep engine RPM toward the upper end of it speed range. That will keep the water pump and therefore heat dissipation up.
So, both retarder and transmission selector need to be used in combination on long grades.
I think that if you find yourself a hill, stop, and engage 1st with the selector, you'll find that engine braking isn't pointless.
Descending long steep grades without a Jacob's brake is simply a matter of keeping your vehicle speed below your brakes ability to dissipate heat. If you're bored, you're probably safe.
Cummins QuickServe Online (https://quickserve.cummins.com/info/qsol/products/newparts/jacobs_md_nondodge.html)
Has anyone used the Jacobs exhaust brake on their motorhome? If so how much did it cost?
Steven,
With the M engine in your U320, you currently have a TRANSMISSION RETARDER.
You can check with Pacbrake, but suspect you could add an EXHAUST BRAKE.
You could also check with Cummins about adding an ENGINE COMPRESSION BRAKE (aka Jake brake) which is more effective than an exhaust brake.
What is your objective/why do you want to move away from/add to the transmission retarder.
Steven, The retarder in your tranny is the strongest way to brake a coach, an engine Jake brake is the second best and exhaust brake (never used by trucks) brings up the rear. I have several folks in my area that can address any tranny issue including the retarder.
While a transmission retarder is a very effective way of slowing a coach on a downgrade, it has it's downsides with increased initial cost, complexity, additional cost of overhaul, overheating transmission fluid, etc. In other words, with a retarder, you pay to play.
Having driven both retarders and Jakes, I much prefer the Jake. Living in the mountains, I think I can speak with more than armchair authority in saying that I leave ours on all the time. It works very well on our steep mountain terrain and with the stock exhaust system, the noise level is never a problem plus it is maintenance free. Nothing worst than being half way down a grade and having the big orange fluid overheat light come on.
How many OTR big rigs have retarders, not Jakes?
Pierce
Pierce, I agree there are issues to deal with using a retarder, but it is still the strongest for an automatic transmission equiped vehicle. Nearly all over the road trucks are manual transmission equiped making the Jake a much better fit and no retarder heating issues to deal with.
Auto transmission equiped fire trucks will have a retarter most times.
I have been shown the jake parts for a m11 at my local Cummins dealer. They had the parts off on a bench.
My research showed used eBay parts were around a thousand dollars plus another thousand to fifteen hundred for the install depending on what's needed for time and materials.
Afterwards I had the factory muffler removed and a jones 5050XL resonator installed.
My thoughts are that without the restrictive muffler the jake might be too noisy.
In a trade off I picked the resonator and the reduced hydraulic pump power loss by changing the over done factory selected fan controller. Used 60 hp as the motor got to operating temperature.
Major difference in the drive with the resonator and the less power losing fan controller. More low rpm power. Much less downshifting. Better mpg by 1 to 1.5.
Temp gauge the same. Source engineering in Oregon has the better fan controller.
My m11 also needed the valves and injectors adjusted and the cam position sensor upgraded and the ambient air pressure sensor upgraded. Both of those Cummins parts were inexpensive.
You could hear the engine misfiring from the partially oil soaked cam position sensor standing behind the coach with the engine idling. Shop manager heard it when he walked behind the coach.
New jake parts were $2,500 range I think when I had looked.
Fully rebuilt brakes and a 110/130 D2 valve in the air system added considerable additional braking with the higher pressure and the brakes ability to not overheat was greatly improved.
With the stronger brakes and the potentially noisier exhaust I put the jake idea on the back burner for a while.
Love to find a jake and resonator are not particularly noisy as I might reconsider the idea.
Hope this helps.
But if we live in the mountains, use the Jake all the time here and on trips with toad, and find it works really well, why would we add the complexity and other problems? Almost every trip sees the coach over Donner Summit on I-80. Do you live in the mountains? No offense intended.
Pierce
Well just from 40 years in the truck and equipment repair trade, a Jake will be noisy with a resonator. As you know a resonator will just take the harshness out of it. My little ISC has a 4" straight pipe. It is LOUD when pulling hard. Enough so that if you are next to traffic barricades you will close to drivers window. At some point I'll install a resonator to help take the bite out of it.
Thanks guys for the feedback, I will check with Cummins and see if I can afford to do it.
Steve
I have both; a retarder and a Jacobs Compression Brake, compliments of the PO.
My retarder and cruise control quit on Friday. The Jake was great.
Tim
Tim your coach info would make the info much more valuable?