Using Jake Brake in traffic

[MyPrevost]

On high always, but in grades of 6-10%, I use the manual transmission selector to slow down since the Jake is pretty ineffective at those grades … at least in my coach.  My brakes appreciate it…

Tim & Cindy
’01 Marathon H, 696 (Sold)
’14 Jeep GC (Sold)
“Travel with a Purpose”

[MyPrevost]

Don’t understand the ineffective Jake’s. If I’m coming to a slow down stop at say a light on a highway, my jakes will (8V92TA) pull it down until I don’t need the brakes but to do final stop. The High stage slows her down pretty good. Is there agjustments on the jakes that causes the problem. Rode in a Detriot Series 60 years ago in a tractor trailer pulling  a modifed Pulling tractor in a Kentucky 53 foot trailer and that Puppy would sure stop you and man was it loud with straight pipes.

[MyPrevost]

My coach has a retarder as opposed to a jake brake. I had a habit of driving with the retarder fully engaged. My coach developed a over heating problem several years ago. In the process of defining the exact cause of the problem the Prevost tech asked me how I utilized the retarder. He told me driving with the retarder fully engaged could cause overheating. The overheating problem was finally traced to a bad wiring harness. He strongly urged me to drive with the retarder engaged in the top position (lowest degree of engagement) and use my hand to fully engage when needed. Works for me.

2021 Millennium H345
Dave & Jill Brewer
Longwood, FL

Owner of 10 Prevost coaches since late 80’s

[MyPrevost]

Walt,

My jake disengages in 1st gear, only works for 2 – 6. Probably can be adjusted at DD.

Tom & Nancy
7 Prevosts Owned

[MyPrevost]

I think maybe Jakes seem ineffective because they sort of are at lower  RPMs.  In slow traffic it doesn’t appear to do that much. But on a downhill it is super effective at about 2300 rpm. I think too if you have the transmission in economy or performance would change your shift points thus the felt effectiveness of the Jake.

On our bus – over a cross country trip I tried to see if you really got better economy in economy.  Didn’t seem like it for me so I always have it in performance now.  The Jake works like a Tesla in traffic on our bus. Pretty well.

I do wonder though – would Prevost design a braking system that couldn’t lock up the brakes?  If they can lock um up – and we assume in a panic you would apply enough foot pressure – the Jake would be unnecessary.   Right? I’m not fighting here…. Just saying I don’t believe the Jake is make or break in a panic stop.  I think the brake braking power would overrule the Jake braking power if you slowed down at a rate faster than the Jake system does. This is the kinda thing that would be cool to figure out on Myth Busters…

mine really does bang the transmission hard at low speeds (5-10 mph.)  I will have to get that checked out. See bout the 1st gear engagement.

2003 Marathon XLII #827
2017 Wrangler Unlimited
Austin, Texas

[MyPrevost]

Locked brakes are totally ineffective. The maximum braking is at a point just shy of lockup and skilled drivers prior to ABS modulated the braking effort to be at that point. All a Jake or retarder does is use the engine braking or transmission braking to asist with pedal effort by instead of applying motive force to the drve axle it is resisting the driving force.

2300 RPM? Are you letting hills drive your engine? However you are getting 2300 it does not sound good.

Jon and Di 2006 Liberty Elegant Lady, 2021
Jeep Grand Cherokee, 1950 Ford
Knoxville, TN

Owner of three Liberty Coaches since 1990

[MyPrevost]

We have a retarder and I use it often.  Because of the glaciers and where we live, we drive through Chicago often.  I’ve found that in heavy traffic the retarder is an effective way of managing our speed without using the service brakes.

Can a Jake brake be retrofitted to a DD Series 60?

Dick & Cathie Karth
1999 XLV Liberty Elegant Lady #405
Have CDL — Will Travel
Shawano, Wisconsin
Member of the Prevost rescue squad
Owner of one Prevost since 2014 … tries not to make things up

[MyPrevost]

Signs, too many too close, too many political dedications. Soon there will be no more places to install dedicated to … signs. I don’t recall seeing any “No Jake Brake” signs. I have seen “No Engine Brake” signs. These signs are dictated to be installed by political morons that have never experienced driving anything larger than their ultra luxurious passenger car. You can see them almost anywhere cutting off big rigs and buses just because they were talking on a cell phone and almost missed the exit they needed to get where they wanted to go. So yeah, let me just cut across your bow, slow down and then exit. I too ignore the signs, besides where they are posted who in there right mind is going to stop a bus, or big rig, on a two lane road with no shoulder to pull over.

We are being led by a government populated with morons!

Carole & Will Garner “Classic” 1990 Country Coach Conversion
Southern Pines, NC

[MyPrevost]

I leave the Jake brake on in traffic, but leave it off on the highway when it is not necessary.  I don’t like unnecessary downshifts when I go down a slight decline.  Jake brake placement is not good, I would have liked to have it next to the cruise control so it’s easier to put my finger on it by feel.

Per
USAF Retired

 

[MyPrevost]

Per,

Why are you getting a down shift on a slight down grade. Have DD program to follow the selected gear, then just a slight throttle pressure keeps the jake off whether cruise or not.

Tom & Nancy
7 Prevosts Owned

[MyPrevost]

His does that because its programmed to try and get to second as soon as possible and it will try and down shift as soon as the cruise set speed is over or you touch the brake pedal or you let foot of throttle, if you just have it go on in sixth then it will not do that , but if its programmed to try and get to fourth or down it will do that , try 5 or  6 , fourth or down is to jerky it will try and get to fourth as soon as it can
We already tried to tell him that, but he liked it to go to second and that’s why , it’s jerky!!! And that’s why it tries and down shift with a slight decline or when it speeds up in cruise , then it tries and down shifts to second.

Peter Campbell2003 Liberty Elegant LadyW/No-See-Um RivetsWheatland Wyoming Owned three Prevosts since 1995.

[MyPrevost]

A jake or retarder that is not enabled 100% of the time is NOT going to be any help when a panic stop is required.

In a panic stop situation nobody is going to be able to find and push the button to engage either the retarder or jake when the entire focus is on getting stopped so there is no collision. If the jake or retarder is turned off except when needed its only purpose is going to be to get more life out of the brake linings.

Jon and Di 2006 Liberty Elegant Lady, 2021
Jeep Grand Cherokee, 1950 Ford
Knoxville, TN

Owner of three Liberty Coaches since 1990

[MyPrevost]

Tom,

Peter has it pretty much right. I had the transmission programmed to downshift to second when the Jake engages.  The jerkiness is really not that bad.  As far as a panic stop, that is what the service brakes are for.  And yes, it does save on the brake linings–I had to replace the pads on the drive axle already.  I suspect previous owners never used the Jake brake.  If you leave it on all the time and don’t downshift, the Jake is pretty much useless.

Per
USAF Retired

 

[MyPrevost]

The question of how best to operate the Jake brake comes up often. The correct answer is to operate it in a fashion that you feel most comfortable with. Some drivers feel most comfortable by leaving it on high all the time. Others choose to determine when and where it is prudent to engage the Jake brake based on road conditions. Therefore, opinions will vary here. As for myself, I feel comfortable determining when and where I feel it is prudent to engage the Jake brake. Given traffic and road conditions nowadays, my Jake stays on most of the time.

I’ve always wondered that if the intent was to run it on all the time, what have an of/on switch? Now I do understand that a selector switch is necessary to allow selection of the Jake to work on 2,3,4 or 6 cylinders based on it’s being a 2 or 3 stage Jake. I also agree that the switch should have been located by the cruise controls on the left horizional panel. That was where it was located on my prior Wanderlodges and worked well as it was easily found when needed. Also, the on/off switch and the stage selector switch were separate and located side by side.

In my opinion, a 3 stage Jake working on just 2 cylinders is almost worthless anyway, so why bother with that stage. Likewise, a 2 stage Jake working on 3 cylinders doesn’t do much in a panic stop. Consequently, most drivers opt for the Jake to be ran on “high” all the time. The end result in most cases is a rapid decrease in speed each time you let off of the accelerator pedal, so there’s no “coasting” of the bus unless you can consciously find the “feather” position at the top of the accelerator pedal as you slow down.

If you haven’t removed the R76 relay, your brake lights are going on and off like a Christmas tree each time the Jake engages because the Jake operation mimics depressing the brake pedal each time you lift the accelerator pedal. These are just some things regarding the jake operation that everyone should be aware of.

So there is no “correct” way regarding when and how you should run your Jake. Run it like you like it…

Chuck & Tela Millsap2003 Marathon XLII SS #8122016 Jeep Cherokee OverlandArizona

[MyPrevost]

However much or little a jake provides, it is still better than nothing. We never know if we are ever in a situation where just 2 extra feet of stopping distance will mean the difference between a crunch or a miss.

What this discussion is exposing however is perhaps the most significant difference between a jake and a retarder, neither of which is 100% perfect. A retarder with the master switch on, but the force of the retarder in the zero position is always on standby, never applies when coasting unless the driver moves the stalk into one of the six positions, but it always assists with braking directly proportional to the braking force. The down side to a retarder is it does heat the transmission fluid.

The jake however can be used with impunity because no matter what amount of force is selected, and no matter how long that force is applied the jake will never overheat anything. Unfortunately it cannot be on and not always applying itself when coasting downhill with the cruise control on.

Jon and Di 2006 Liberty Elegant Lady, 2021
Jeep Grand Cherokee, 1950 Ford
Knoxville, TN

Owner of three Liberty Coaches since 1990

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