Exhaust Brake Use

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Tom:

I talked to a couple of FCOC members who have installed the Brakeswitch. They reccommended calling Hawkes if you have questions.
 
Note that he doesn't actually have a Jacobs brand brake and is using the term "jake brake" generically.  The Cummins ISL 400 has an optional 2 stage compression brake from Cummins and may have its own variety of controls and operating procedures. I have no idea what "2 stage means either. 

Anybody out there have an ISL 400 with the brake option?
 
RV Roamer said:
I have no idea what "2 stage means either. 
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In the case of a "REAL" engine brake, they come in both 2 and 3 stage models. A 2 stage will use either 3 or 6 cylinders  for the braking and a 3 stage will use 2, 4, or 6 cylinders, for different amounts of braking. My CAT 3176 has a two stage JAKE,  CAT publishes curves which show the braking horsepower at different engine RPMs. My unit will apply the equivalent of 190 HP retarding power at 1600 rpms when braking with all 6 cylinders,which  does drag you back quit noticeably.

Chet18013
 
I don't know of any Monaco owners that have installed one but you might check on either the Monaco list or the Diesel-RV list on Yahoo.

Every one I have met that has one, likes it.

Homer is a good source but in my case, he was wrong.? I had to figure it out on my own.? Not a big problem but I needed the chassis schematics for it to be able to do it.? I found all the connections I needed in the dash so did not have to wire through the firewall etc.? ?A little tricky but it made a real clean installation.? VBG
 
Thanks Jim. I'll do more research and think on it. Meanwhile, I had Monaco install the foot pedal for the Pac Brake while we were at the FMCA rally. I was actually on my way back to the parts trailer to return it when I ran into Jerry Fitzgerald and he convinced me to keep it.

The pedal operates in parallel with the rocker switch on the side, which eliminates one distraction for the driver. Haven't been on any significant downgrades since it was installed, so our only indications that it's working are the light in the rocker switch illuminates and the cruise control disengages.

I hope it's not a placebo  :(
 
RV Roamer said:
Note that he doesn't actually have a Jacobs brand brake and is using the term "jake brake" generically.  The Cummins ISL 400 has an optional 2 stage compression brake from Cummins and may have its own variety of controls and operating procedures. I have no idea what "2 stage means either. 

Anybody out there have an ISL 400 with the brake option?
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Gary

As I've mentioned to Keith I have the same power train as on his Newmar Mountain Aire; Cummins ISL-400 engine with Cummins engine compression brake and the Allison 3000MH transmission all on a Spartan Mountain Master GT chassis.

There is only one driver control put on the coach, a 3 position rocker with "High", "Low" and off positions. The High position utilizes all 6 engine cylinders in the compression braking, the Low position only uses 3. Standard from the Spartan factory is seeking to 4th gear when the brake is engaged, the cruise control continues to work if on. If the cruise speed is exceeded, such as on a downhill, the compression braking and downshifting will be activated. Once the cruise speed is reached again, the cruise takes over, the compression braking is released and 6th gear is targeted again. All without intervention by the driver.
 
The verdict is in for the PacBrake foot pedal that JerryF convinced me to have installed - it's a keeper!

Today I got to drive the coach for several hours, including over Tehachapi Pass (long downgrades), which gave me the opportunity to compare between PacBrake usage with the regular rocker switch and usage with the foot pedal. The foot pedal wins hands down. Pros of the foot pedal:

  • No distraction for the driver, trying to find the switch and no delay while s/he finds it. The pedal is right there by the driver's left foot.
  • The PacBrake is operational only for as long as light pressure is maintained on the pedal. So the driver determines if, when and for how long the PacBrake is applied. When the rocker switch is on, the brake comes on as soon as zero accelerator position is detected and the only thing the driver can do to release it is to press the gas pedal.
  • With a little practice, it's possible to choose which gear to stay in when descending a grade. With the rocker switch, 'zero accelerator' immediately requests 2nd gear. I realize the Allison won't downshift until it's safe to do so, but the driver has no say in which gear is requested or selected.
  • Also with a little practice, it's possible to control the amount of exhaust braking in normal traffic, avoiding the lurching that's present when the rocker switch is left on.
  • All the above are achieved without needing to depress the service brake pedal, even momentarily.

A big thanks to Jerry for convincing me to keep the pedal when I was on my way to the Monaco parts trailer in Pomona to return it. Also thanks to Ardra for convincing Chris it was worth trying.
 
Tom

I find the brake switch falls easily to hand without any searching. I switch mine off and on (did the same with our Damon). This makes it easy to turn off the brake effect without having to feed the fuel pedal. Whenever the Pac-Brake is activated, it "searches" for 2nd gear, does not shift to second. It will downshift to 5th, then 4th, then 3rd first.
 
We are with you Bernie.  We have no distraction finding the switch and prefer it to a foot pedal.  Guess it is just a matter of personal preference.
 
Even if you can find it easily, I cannot imagine switching the rocker switch on and off continuously, which is what the foor pedal is designed for. I'm not talking about occasional switching, but pressing it on and off several times as required on the same long grade. I'd rather keep two hands on the wheel - much safer.

BTW my rocker switch still works - one of my requirements when I had Monaco install the foot pedal was that I would have the option of using either one. That's how I was able to make repeated comparisons of the two.
 
I don't have any idea why one would find the need to switch the Pac brake on and off continuously.  We don't find that need.  Just another case of personal preference.
 
Tom said:
Even if you can find it easily, I cannot imagine switching the rocker switch on and off continuously, which is what the foor pedal is designed for. I'm not talking about occasional switching, but pressing it on and off several times as required on the same long grade. I'd rather keep two hands on the wheel - much safer.
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Tom

As I said, I find the rocker in a very natural location and it just falls to hand. Very easy to work.
 
Tom said:
Even if you can find it easily, I cannot imagine switching the rocker switch on and off continuously, which is what the floor pedal is designed for. I'm not talking about occasional switching, but pressing it on and off several times as required on the same long grade. I'd rather keep two hands on the wheel - much safer.
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Tom,

There is no need to switch the Pac Brake off on a long down grade.  Just apply a slight pressure to the accelerator and the Pac Brake will slack off a little.  Or, leave the cruise control on and let the computers do all the work.  The parameters for the interaction of the cruise control and the Pac Brake can be set to your preference with software available from Cummins.

Phil
 
I was sceptical too when Jerry first told me about it, but he convinced me to try it and I reserved judgement. I'm glad Jerry was persistent. Having the opportunity to try them side by side for several hours yesterday made me a believer.

BTW I'm not trying to convince anyone of anything in this discussion; I'm merely reporting the results of something I previously said I was going to try.

Bernie, maybe Monaco mounts their switches in a different position. Our friends who recently order a new coach specified a different position for the switch to avoid the need to "find" it.

Since Jerry has had experience using the foot pedal with both a Pac Brake and a Jake Brake, maybe he could give us a rundown at Moab. Heck, he might even let us drive his coach on one of the off-road trips that has lots of steep down grades  ;D
 
Phil said:
Tom,

There is no need to switch the Pac Brake off on a long down grade.? Just apply a slight pressure to the accelerator and the Pac Brake will slack off a little.? Or, leave the cruise control on and let the computers do all the work.? The parameters for the interaction of the cruise control and the Pac Brake can be set to your preference with software available from Cummins.

Phil
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That is the way ours is set up in addition to the switch being located in a very comfortable position.
 
As I said, I'm not trying to convince anyone of anything, merely reporting results. Save judgement until you've tried them side by side on the same coach as I did for several hours yesterday; Then report the results.

There is a noticable difference between the two methods of applying the Pac Brake. On our coach, leaving the the rocker switch on, the only time the Pac Brake will come on is at zero accelerator position and it shuts off with depressing the gas pedal. The result, when combined with the down/upshifting, can be a bit lumpy. The foot pedal allows the driver more control over when the PB is applied and, in my tests yesterday, allows for smoother braking.
 
Tom said:
There is a noticable difference between the two methods of applying the Pac Brake. On our coach, leaving the the rocker switch on, the only time the Pac Brake will come on is at zero accelerator position and it shuts off with depressing the gas pedal. The result, when combined with the down/upshifting, can be a bit lumpy.
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Tom,

Try leaving the cruise control on and the Pac Brake switch on during a down hill run. 

I drove a lot of miles with the Monaco foot switch before I decided that I did not like it.

Phil
 
Depending on how it's wired, some exhaust brakes, like ours, turn off the cruise control as soon as they actuate.  We have to manually turn it back on when it's wanted again.
 
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