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Author Topic: Teach me about Jake Brakes  (Read 4154 times)
DrivingMissLazy
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« Reply #30 on: November 05, 2007, 05:38:45 AM »

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Anyone experienced with a Jake on a standard knows what happens when you forget to switch it off before leaving the driver's seat. (Engine stall, if you are wondering)

I  have only driven a Jake equipped coach with an automatic. Can someone explain why leaving the switch on would cause the engine to stall on a manual tranny equipped coach. At idle speed, the Jake should be inoperative in my experience.

Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
akroyaleagle
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« Reply #31 on: November 05, 2007, 06:19:50 AM »

Richard,
The Jake on an automatic will not function when the torque converter drops out of lockup. Manuals don't have lockup.
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Joe Laird
'78 Eagle
Huron, South Dakota
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« Reply #32 on: November 05, 2007, 06:40:28 AM »

Joe, please excuse a dumb ole redneck hillbilly for not understanding, but my Jakes quit working when the rpm drops down to about 1,000 RPM, (not enough oil pressure to actuate the solenoids). So how could they cause the engine to stall when the idle rpm is in the 500 rpm range. I am assuming the tranny is out of gear and/or the clutch is depressed.
Richard


Richard,
The Jake on an automatic will not function when the torque converter drops out of lockup. Manuals don't have lockup.
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Dallas
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« Reply #33 on: November 05, 2007, 06:49:56 AM »

Richard,

I think your jakes quit working, not because of low oil pressure, but because of a low pressure switch in the transmission.

At 1000 rpm, you should be close to full oil pressure on a DD 2 stroke.

On my NTC 400 BCIV cummins, RTOO 14613, there was a switch that would disengage the jake at low rpm. I know this because the switch went out once and the jake would kill the engine at idle unless the clutch was depressed or there was light pressure on the accelerator pedal.. on a cummins that's about 25psi oil pressure.

IHTH

Dallas
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akroyaleagle
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« Reply #34 on: November 05, 2007, 06:53:41 AM »

Richard, on automatics the Jake only works when the transmission is in lockup. On manuals it works all the time the clutch is engaged. Jakes are more efficient at higher rpms. Yours is probably working at 1000 (If you are in lockup) but is so inefficient it seems it isn't. At 2250 (max no load in my Eagle) the Jake is most efficient and efficiency decreases as the rpm lessens.

Most of us do not drive through towns At 2300 rpm. If you have the correct muffler(s) on the coach the Jake really doesn't make much noise. The laws are to keep unmuffled trucks from waking up the area.

In the Pacific Northwest the log trucks I've seen make a LOT of noise when the Jakes is on. Also many drivers pop them a lot in truck stops. I don't know why except maybe to get noticed.

Modern Jakes have up to six stages of braking. Mine has two. High and Low. I find leaving it on all the time works for me. It doesn't work below about 18mph when the transmission drops out of lockup. Mine works great. Cruise will work as the transmission down shifts in a climb. (It doesn't down shift much with the 8V92). On the descent, remember the cruise is pulling on the fuel lever so the Jake doesn't come on until cruise backs off. On long grades in the west I do turn my cruise off.

We should wire the Jake to the brake lights but I haven't done that. It hasn't gotten high enough on my list of things to do. I think it is a good idea to let the folks following know you are decelerating. The cruise also drops off anytime the brake lights are on. If the brake lights are not functioning, The cruise will try to speed up anytime the brakes are applied. That is not good.

« Last Edit: November 05, 2007, 07:01:24 AM by akroyaleagle » Logged

Joe Laird
'78 Eagle
Huron, South Dakota
DrivingMissLazy
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« Reply #35 on: November 05, 2007, 07:15:32 AM »

It all sounds great, but my Jakes are not wired thru the tranny. And at idle the engine does not stall when the Jakes are turned on. As I recall, the Jake literature also mentions that the Jakes will not operate at idle rpm due to low oil pressure. My oil pressure at idle is about 5 pounds .
Oh well, enough of this. Just one of the mysteries of life I guess.

Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
TomC
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« Reply #36 on: November 05, 2007, 07:51:42 AM »

There is a way of hooking up the Jake so the only switches on it would be the throttle and clutch (and obviously the switch on the dash).  On this type of setup, on an engine that maintains oil pressure at idle, like a Cummins or like the Caterpillar I have in my truck, the Jake can start activating causing the engine to surge and burp with the Jakes trying to work-usually eventually stalling out the engine.  On my truck, the stop solenoid shorted out, so the engine stayed stopped.  I removed the solenoid and to turn off the engine would just turn on the Jake, rev it up to only about 1000 and release the throttle and would stall out the engine.  If the Jake is properly wired, it should also include a switch in the governor so that when it comes down to an idle, it disengages the Jake, then you won't have the problem of Jake activation when idling.  If you have an electronic engine, this feature will be built in.  If you have a Detroit 2 stroke with the Jake switch on the governor, it too is built in-course you also won't have enough oil pressure at idle either.  Only 4 strokers with mechanical injection and not properly wired might have this problem of Jake operation at idle.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #37 on: November 05, 2007, 04:32:22 PM »

Richard,

I've always set my Jakes with the engine running and at operating temp.

Others,

I do not have DDEC in my Eagle but I have driven many tour buses that had Series 60's and B500s and they interacted just like my Eagle with the 8V92 and 740.

My Jake doesn't activate until the cruise drops out when above the set speed.

The cruise doesn't know the Jake is on, it only knows to come on and drop off according to the selected speed.

The Jake doesn't know anything about cruise. It only knows the cruise has released the throttle lever and it should activate. When the cruise pulls the throttle lever, it causes the Jake to think you have given more fuel and it quits.

If your Cruise is hooked up to the linkage somewhere downstream of the throttle lever, change it so it only pulls the fuel arm and not the whole linkage.

The only time I would turn off my Jakes would be when the road is slick as BK pointed out.

My theory was and is, make everything as automatic as possible. None of us will ever get any younger or have better memory.

Hope this helps

As much as I like being giv'n credit when I deserve it, I also feel I should note when it is giv'n to me by mistake! I believe the credit should be giv'n to BW aka Bus Warrior! But many thanks anyway! As it is something I would have said, but since I've been away from the computer it wasn't me this time as this is my first reply on this post!

Now as to the subject of the Jakes stalling an engine at idle, I have seen it as TomC points out on a CAT and also on a Cumapart both installed by backyard mechs. that only used throttle,clutch, & dash switches and eliminated some of the other stuff! I have pulled into a truck stop and got out to start fueling and had the truck start shaking, choking, & smoking b4 the engine violently shut down because I'd forgoten to turn the dash switch for the Jake off! Ya every one else notices too! LOL! Oops that's what happens when you borrow a truck or help a friend out and drive an unfamiliar truck for the first time! And just for the record, NONE of our coaches have Jakes, but my SETRA's have awesome retarders! (speaking of which mom & dad drove an '05 S417 this weekend and LOVED it, and one of the things dad noticed the most was that the retarder would stand you on your nose! and surprisingly did so to him going down Mount Eagle! LOL! {as a side note I'm just glad they finally drove something besides an antique 102A3 for a change! LOL!) Also on my big trucks I had a terrible habit of leaving the Jakes on in fair to great weather, but NEVER left them on if there was even a chance of rain or worse! I did love being able to set the cruise (at speeds we won't mention) out west and letting the truck do the work! Of course we didn't have no sissy (oops I mean auto) tranys either! LOL!  Grin  BK  Grin
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artglass
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« Reply #38 on: November 05, 2007, 04:41:28 PM »

is there solnoids for 24 volts and 12 volt or are they all the same, found a set off of a truck i assume they are for 12 volt.
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akroyaleagle
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« Reply #39 on: November 05, 2007, 05:25:51 PM »

It all sounds great, but my Jakes are not wired thru the tranny. And at idle the engine does not stall when the Jakes are turned on. As I recall, the Jake literature also mentions that the Jakes will not operate at idle rpm due to low oil pressure. My oil pressure at idle is about 5 pounds .
Oh well, enough of this. Just one of the mysteries of life I guess.

Richard


Our Jakes are not wired through the trans.

The only time the Jake should work is when the throttle has no fuel applied and sufficient oil pressure. When parked or below your lockup speed the trans is not in lockup and the trans is disengaged from the drive train so no braking action.

My idling oil pressure is 20-25 and my Jake has never come on at idle.

I am getting older but I try to turn off all unneeded switches so probably don't have it on at idle. I do have it on when driving. I guess that comes from pulling such a large trailer with the Eagle and knowing it may help me keep from rear ending somebody when the suns in my eyes and I'm half asleep.

This thread has turned from a request for info to whatever it has become. I think I will move out of this discussion and try to provide the info requested.

There are 12v and 24 volt solenoids. They do not interchange but you can just change them to the correct ones.
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Joe Laird
'78 Eagle
Huron, South Dakota
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