Skip to main content ↑ ↓
Topic: Two stage Jake brake? (Read 1462 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Two stage Jake brake?

Yahoo Message Number: 10829
We just returned from a trip that covered Wolf Creek Pass, Slumgullion Pass, Spring Creek Pass and more. The coach did fine as did the Jake brake. The question is---The Jake brake is supposed to be a two stage (3 & 6) brake but I could not tell the difference between the two switch positions. Does anyone out there have a Jake that actually has a noteable difference in the two positons? Lyle, 04 Intrigue 11740

Re: Two stage Jake brake?

Reply #1 –
Yahoo Message Number: 10830
I've found that you feel the second stage only if you are in a lower gear.
My transmission is set up to 'seek 4th gear' on the ECM Jake signal. I feel better

if I'm in 3rd gear (or lower) in most cases. I plan to get the Allison folks to

program the transmission to seek 3rd on the next maint visit.

Sounds like your having a fun trip!

JimC

2002 Intrigue 11446

Re: Two stage Jake brake?

Reply #2 –
Yahoo Message Number: 10831
Lyle:

I, too, came through Wolf Creek Pass on July 12 heading in an easterly direction. In fact, I saw a coach which looked just like mine west of the pass heading west. Could that have been you?
With respect to the Jake brake, I can certainly feel the difference between the two stages. When I use the second stage, the Allison shifts down to 4th once the coach is going slow enough to do it. Negotiating some of Wolf Creek Pass got a bit steep and I manually shifted to 3rd and even 2nd briefly. Rarely did I need to use the foot brake and then only to help slow it so it could downshift.
The first stage is OK for slow moving level traffic, but I agree it is not that noticeable when it engages. It does have some effect though. Got to be careful not to engage it if going too fast as you approach high rpms quickly.
I read somewhere that originally the Allison would shift to 3rd vice 4th when the Jake brake was engaged, but this was too aggressive for a lot of people. Hence it was reprogrammed to down shift to 4th. I think I might have read that in one of the Destination magazines.

Chuck

03 Intrigue 11673

Re: Two stage Jake brake?

Reply #3 –
Yahoo Message Number: 10841
Quote
Quote from: cpenque@a...
Chuck,

Thanks for the input. First---no that wasn't me on Wolf Creek Pass. We came through there on July 16. Now, about the Jake. My tranny is programmed to seek 2nd gear when the Jake is engaged. Of course it will only drop to a gear that is acceptable on RPMs and then work its way down. You should have no fear about watching your RPM before engaging the Jake since the Cummins (do you have Cummins?)will not over rev. It will jump up a gear if the RPM gets too high. Further, the two stage Jake initiates a different number of cylinders, as I understand it, for each of the two stages. At least that's what I think it is supposed to do. Three on stage one and six on stage two.
If that is the case there should be a huge difference between the stages. Does anyone have a different view? Sure would like to understand this a bit better.
Lyle, 04 Intrigue 11740
Lyle:
> I, too, came through Wolf Creek Pass on July 12 heading in an easterly > direction. In fact, I saw a coach which looked just like mine west of the pass

heading west. Could that have been you? > > With respect to the Jake brake, I can certainly feel the difference between

the two stages. When I use the second stage, the Allison shifts down to 4th

once the coach is going slow enough to do it. Negotiating some of Wolf Creek

Pass got a bit steep and I manually shifted to 3rd and even 2nd briefly.

Rarely did I need to use the foot brake and then only to help slow it so it could
downshift.
> The first stage is OK for slow moving level traffic, but I agree it is not

that noticeable when it engages. It does have some effect though.
Got to be

careful not to engage it if going too fast as you approach high rpms quickly.
> I read somewhere that originally the Allison would shift to 3rd vice 4th

when the Jake brake was engaged, but this was too aggressive for a lot of

people. Hence it was reprogrammed to down shift to 4th. I think I might have read

that in one of the Destination magazines.

Chuck

03 Intrigue 11673

Re: Two stage Jake brake?

Reply #4 –
Yahoo Message Number: 10844
Lyle, if you have Cummins, you may not have a Jake brake. You might have a Jacobs brake [not the same as a Jake] or a Pac brake. I don't know this as gospel only repeating what was told to us in a diesel engine class at Life on Wheels.
The instructor indicated that the CAT engine "usually" has the Jake brake. I have a CAT in my coach and it has a 3 stage Jake and the tranny is programmed to go to 4th.
Just info repeated as I heard it!
Larry

'99 Affinity

Re: Two stage Jake brake?

Reply #5 –
Yahoo Message Number: 10852
Lyle;

My 2003 Intrigue has a Cummins 400 ISL engine with an internal 2- stage Jake brake. Older model Cummins engines (which ones I'm not sure) used a external Pac brake, but the ISL definately has an internal 2-stage Jake.

There is definately a difference between stage 1 (3 cylinder braking) and stage 2 (6 cylinder braking). It is most easily noticed when traveling down a long mountain grade in a lower gear.
On our trip back home from Junction City, we traveled over the Rockies and went down many long mountain grades. I'd usually shift into 3rd gear at the top of the hill with the Stage 1 Jake brake on. Then as we went down the hill, I'd toggle to Stage 2 if I felt like I needed to slow down a bit more. Then when I'd get going too slowly, I'd flip back to Stage 1 and coast up to a slightly higher speed. Just flipping back and forth between Stage 1 and Stage 2 provided the perfect level of control I needed to maintain a comfortable speed without the use of my service brakes.

Also, note I said that it is always best to set your gear selection at the TOP of the hill before starting your descent. Select a gear that you know for certain will be low enough at the TOP of the hill (usually 3rd but sometimes even 2nd may be required on very steep and curvy declines). If you wait to select the correct gear half way down the mountain, your Cummins computer may prevent the downshift to prevent engine damage. Then you'll be forced to use the service brakes to slow down while going down a steep hill faster than you'd like. Using service brakes should always be a last resort since proper selection of gear at the TOP of the hill and proper use of your Jake will always give you the control you need.
If your service brakes overheat and the Cummins computer prevents a downshift, then your stuck in a very difficult situation flying down the mountain with no brakes and no Jake! Also, note that the Jake does not engage in 1st gear, so forget about that option for super slow and steep descents - you'll have to use 2nd gear and Stage 2 Jake and maybe even your service brakes too.

And, don't be afraid to use a lower gear to get more Jake braking effect. The computers that control the engine and transmission will not shift to a lower gear if it shift will cause over-revving or any engine damage. Upshifting is never a problem if you're in a gear that is too slow.

My transmission automatically SELECTs 4th gear when the Jake is engaged. Often, I will then manually SELECT 2nd gear if I want maximum Jake braking to save my service brakes (like when approaching a red light or at the bottom of an exit ramp). The engine and transmission computers will then SHIFT down automatically to a lower gear as the coach slows down. Remember - just because you SELECT a gear does not mean that the transmission will SHIFT to that gear. It will only do so when it can do so without damage to the engine. That's why I emphasize the words SELECT and SHIFT.

This can be easily demonstrated by an example that may save your life. When traveling back over the Rockies, I crested a hill and proceeded down the other side. There were no markings to indicate a steep decline so I didn't bother to downshift at the top of the hill. After I crested the top and started down, I realized I was going to fast, so I flipped on the Jake. The LED showed that 4th gear was SELECTED, but to my BIG surprise, the engine did NOT DOWNSHIFT and the Jake did NOT engage. The reason, I was going too fast. After applying the service brakes, the Jake did engage and the transmission downshifted to 4th. I then SELECTed 3rd gear, but it would not downSHIFT because I was still going too fast. After further application of the service brakes, it did downSHIFT to 3rd gear. I then toggled between Stage 1 and 2 to safely control my speed down the long grade.

I hope this information sharing helps you and others who read this.

Kindest regards,
Robert Kumza
2003 Intrigue

Re: Two stage Jake brake?

Reply #6 –
Yahoo Message Number: 10857
Quote from: rvrobert2003"
r />]
Robert,

Thanks for the input. I understand well your treatise on hill driving as I live in New Mexico and travel the Rockies often. The difference in our two coachs is that my Allison is programed to select 2nd gear when the Jake is on and there is only idle fuel flow to the engine.
Thus, anytime I apply Jake I don't have to worry about selecting the proper gear, it will chose the lowest gear possible all the way down to 2nd. Of course, at times that is too slow so then I manually select gears and Jake when needed. Now, the problem is that I cannot detect any difference in the two Jake switch positions. I have studied the schematics and talked to CC. So far my conclusion is that my coach may have been wired for only a single stage Jake. There is suppossed to be a 87 type relay aft of the switch to control which stage is in operation. So far I cannot find such a relay anywhere.
If anyone knows where this relay is I sure would appreciate some feedback. If there is one it could be inop or it could just be wired wrong. CC admits that Cummins has had some wiring problems on this issue but that would entail pulling the head---hope that does not have to be done.
Thanks again,

Lyle, 04 Intrigue 11740

Re: Two stage Jake brake?

Reply #7 –
Yahoo Message Number: 10866
Lyle,

There should definitely be a big difference in the two positions.
Which engine do you have? Since you have an '04, I would assume you have the 400HP Cummins ISL. With out Caterpillar, we have a three- stage, working two, four, or all six cylinders, and there is a big difference between each stage. The Jake comes on with the throttle all the way off, so I've found I can "feather" the throttle to leave the transmission in the low gear selected, but add a little throttle to turn the Jake on and off depending on need. If you have a true Jake, and there is no difference, there is something wrong. I suppose you know that if your cruise is on, the Jake won't engage unless you step on the brake, right? The tranny will downshift, but the Jake won't engage.
Per

95 Affinity

Quote from: Lyle Wetherholt
> We just returned from a trip that covered Wolf Creek Pass,

Slumgullion

Quote
Pass, Spring Creek Pass and more. The coach did fine as did the

Jake

Quote
brake. The question is---The Jake brake is supposed to be a two

stage

Quote
(3 & 6) brake but I could not tell the difference between the two > switch positions. Does anyone out there have a Jake that actually

has

Re: Two stage Jake brake?

Reply #8 –
Yahoo Message Number: 10873
Yes, sir. The up position will hold my coach at 55 on a 6% grade in 4th gear. The down position is only good for about 4%. TWI 11731 42" Ovation.
I have done Wolf Creek, but going down into Lake City must have been a real challenge. Third or second gear?

Re: Two stage Jake brake?

Reply #9 –
Yahoo Message Number: 10876
Quote from: totenard"
r />]
Per,

Thanks for the input. Yep, it is a Cummins 400hp. Nope, no difference in switch positions. CC told me where to look for an 87 type relay that initiates the Jake stages but guess what--no relay to be found. Either it is hidden or they didn't wire one in.
Lyle, 04 Intrigue

Re: Two stage Jake brake?

Reply #10 –
Yahoo Message Number: 10877
Quote from: C. Marshall"
r />]
C. Marshall,

2nd gear on several occassions. We were headed south on that leg of our trip so the Lake City portion was a climb from Gunnison. But Slumgullion gave us some 2nd gear operation as did Wolf Creek. BTW, for anyone headed that way Wolf Creek is under construction and long delays are not uncommon. One lane in some places and rough road.
Lyle, 04 Intrigue 11740

Quote
Yes, sir. The up position will hold my coach at 55 on a 6% grade in 4th > gear. The down position is only good for about 4%. TWI 11731 42"

Ovation.

Quote
I have done Wolf Creek, but going down into Lake City must have been

a real
 

Re: Two stage Jake brake?

Reply #11 –
Yahoo Message Number: 10879
A good rule of thumb when going down a hill is to use the same gear you used coming up. thats where I start when decending.

Bill G 2005 Magna #6425 just took delivery