Jacob's Brake
07-19-2009, 09:40 PM
#1
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Jacob's Brake
I understand a Jake Brake brakes the motor and while watching Ice Road Truckers a question arose in my head. They say you shouldn't hit brakes while going down hills etc. etc. MY QUESTION:
What does a Jake Brake actually slow down, and why not just use it to slow down going down the whole hill instead of in short bursts?
Really off topic I hope I found the right place to post haah!
Brandon
What does a Jake Brake actually slow down, and why not just use it to slow down going down the whole hill instead of in short bursts?
Really off topic I hope I found the right place to post haah!
Brandon
07-20-2009, 04:20 AM
#2
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A Jake actually changes the timing of the exhaust valves opening. So lets say on a compression stroke when the piston is coming up to TDC there would be combustion/ignition of the fuel forcing the piston down creating power to transfer to the wheels via drivetrain right ? A jake opens the exhaust valves early so there is virtually no power transfered to the piston to create the downward force. Removing power from the engine conversely removing power from the wheels. In a crude explanation that's how it works.
07-21-2009, 08:58 AM
#6
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ok, so lets see if i get it
by having another soleniod keep the exhaust valve open, no power is produced to the wheels, but by the engine still turning, it acts as a brake to the wheels?
by having another soleniod keep the exhaust valve open, no power is produced to the wheels, but by the engine still turning, it acts as a brake to the wheels?
07-21-2009, 09:37 AM
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Ya pretty much it. The engine is still running just like it normally would but with no power being made the motor slows.
08-19-2009, 09:42 AM
#8
thinkin with me dipstick
yay! jake brake, lets bend some pushrods!
slows the motor down, which slows the entire drivetrain... makes the truck really loud too - i'm sure you've seen one of these
slows the motor down, which slows the entire drivetrain... makes the truck really loud too - i'm sure you've seen one of these
03-31-2010, 03:12 PM
#10
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They also use exhaust brakes. They act just like a gas engine with a manual trans when you either let off the gas or downshift. The "motors' reducing speed" brakes the speed.
I use them full time, on my dodge cummins diesels.
Saves the braking system components and increases the required service intervals by 100-150% We went 240K miles without anything being done to brakes on a dually.
I use them full time, on my dodge cummins diesels.
Saves the braking system components and increases the required service intervals by 100-150% We went 240K miles without anything being done to brakes on a dually.
03-31-2010, 04:06 PM
#11
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The reason you don't use them all the time on an icy hill is they will actually stall the engine and lock up the drivers. You then jacknife. The worst sound you'll ever hear from a desiel on an icy hill is silence. You can use them all the way down a hill that has good traction, also most jakes have a hi and lo setting for different load and road conditions. I like retarders better, they use engine oil pumped into a impeller system setup at the back of the engine and they will not lock up but do heat the oil up on a long hill.
05-27-2010, 04:42 AM
#12
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I also like retarders there at least quieter but....at least all the retarders I have seen all work off the transmission not the engine.
05-27-2010, 04:48 AM
#13
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06-19-2010, 08:38 PM
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The hydraulic brake retarders are a whole different animal. Engine hydraulic retarders are mounted on the engine. The Caterpillar Brake Saver is the most popular retarder in this class. This retarder operates on the torque converter principle.
In a normal torque converter, vanes on the input housing (which is attached to the engine crankshaft) transmit power through the fluid coupling to the output shaft vanes of the torque converter, which is connected to the input shaft of the transmission. The hydraulic retarder transmits power from the rotor vanes (which are attached to the engine crankshaft) to the retarder housing vanes (which are attached to the engine block or bellhousing). This produces a hydraulic drag which absorbs vehicle motion energy while activated.To activate the hydraulic retarder, oil is pumped into the housing, and the housing vanes exert drag due to the swirling oil, upon the rotor vanes. To stop the retarder action, simply drain the chamber, which uncouples the two vanes.
The retarder oil pressure supply is delivered from a secondary section of the engine oil pump. The oil used for the retarder comes from the oil sump of the engine, which must therefore have a larger capacity. This section of the oil pump is entirely separate from the engine lubrication section of the oil pump. This oil pump pressure can be modulated before it reaches the retarder housing. More oil pressure in the retarder housing means more retarding action. Less oil pressure results in less retarding action. While the oil is pressurized within the retarder housing, it is constantly being circulated through the oil cooler and back into the oil sump. This is required to remove the heat generated by the retarder friction.
This retarder has a BrakeSaver control valve which regulates the retarder action once it is activated. This control valve in conjunction with a driver control handle, will set a specific retarder action. As the engine slows in RPM due to the retarding action, the BrakeSaver control valve automatically increases the oil pressure in the retarder housing, which keeps the braking action constant as the pumping action of the retarder vanes decreases.
The retarder control valve also provides a proportioning valve function. The driver control handle will set the retarder force desired, when in manual mode, but while in auto mode, the driver's release of both the throttle and the clutch pedal, will apply maximum retarder action automatically. The proportioning valve uses the larger of these two pressures to control the retarding action.
As required with the above retarders, engine RPM must be kept high for the most retarder effect
06-20-2010, 08:11 AM
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http://www.svfd.net/SVFD%20Files/Art...0It%20Work.pdf
06-20-2010, 07:49 PM
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Allison trannies are Automatics and are very rarly used in hyway tractors.
I've owned a couple of hyway tractors (Pete's) with Cat 3406 engines and the brake saver retarder and as described in the artical I posted they are on the engines.
Heavy constructon equipment have automatics and have the tranny retarders not hyway trucks. Right now I'm in the Horn Basin gas feilds in northern BC and I spend 12 hrs a day 7 days a week in a Volvo A30 Rock Truck so I know from direct experince with both kinds of retarders.
Here's a hill that I've used the retarder on hundreds of times.
I've owned a couple of hyway tractors (Pete's) with Cat 3406 engines and the brake saver retarder and as described in the artical I posted they are on the engines.
Heavy constructon equipment have automatics and have the tranny retarders not hyway trucks. Right now I'm in the Horn Basin gas feilds in northern BC and I spend 12 hrs a day 7 days a week in a Volvo A30 Rock Truck so I know from direct experince with both kinds of retarders.
Here's a hill that I've used the retarder on hundreds of times.
Last edited by toad490; 06-20-2010 at 08:22 PM.
06-21-2010, 05:24 AM
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Al right now lookie here. I never said that there wasnt a retarder mounted on the engine I just said I never seen one. You, on the other hand said there was no such thing as a transmission retarder I say bull ****. First off I never said anything about automatic or manual shift your right Allision only makes automatics and......your point? I repair fire trucks (I say again, fire TRUCKS). Our older pumpers which are mounted on Ford chassies have transmission retarders, no bull. Some of them use what is call a telma which is a drive line retarder, works llike on the same principle as a alternater the magnetic field is what caused the braking action. Exactly whats in over the road trucks or heavy equipment well I dont really care I'm not going to bump heads with you. Have a nice day
Last edited by sweeperking; 06-21-2010 at 06:01 AM. Reason: spelling mistakes
06-21-2010, 07:42 PM
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Well if there's a question on repairing fire trucks we know who to go too. Your knowledge of hyway trucks and heavy equipment obviously dosn't come from any direct experince and is inaccurate, and seeing the OP is on hyway trucks {and you brought up heavy equipment} what was your point and in calling into question my saying how they work on hyway tractors, bearing in mind the OP was on hyway tractors?
06-22-2010, 08:23 AM
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Your knowledge of hyway trucks and heavy equipment obviously dosn't come from any direct experince and is inaccurate, and seeing the OP is on hyway trucks {and you brought up heavy equipment} what was your point and in calling into question my saying how they work on hyway tractors, bearing in mind the OP was on hyway tractors?
06-22-2010, 09:02 AM
#20
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wow. i never heard of transmission brakes before i read this,(learned a new thing) heard of engine/exaust brakes, im not getting in the middle cuz i have no clue,
06-25-2010, 08:43 PM
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Lets review your posts.
So you've seen very few retarders, that we now know.
Did you not read the artical on the brake saver or are you really that dense?
No I'm not, I drive them for a living and heavy construction epuipment have auto tranny's and if you will stop and think {don't hurt yourself} about it an engine retarder would do no good with an auto, they have to have a tranny retarder.
Yes you did read your post, see the second quote.
Yes I do, the internet is full of guys like you.
LOL, You'd better stick to disco!!
No there on the transmissionf
No I'm not, I drive them for a living and heavy construction epuipment have auto tranny's and if you will stop and think {don't hurt yourself} about it an engine retarder would do no good with an auto, they have to have a tranny retarder.
Originally Posted by ;48441
I never said that there wasnt a retarder mounted on the engine
Yes I do, the internet is full of guys like you.
LOL, You'd better stick to disco!!
Last edited by toad490; 06-25-2010 at 08:58 PM.
06-25-2010, 08:52 PM
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So you've seen very few retarders, that we now know.
Did you not read the artical on the brake saver or are you really that dense?
No I'm not, heavy construction epuipment have auto tranny's and if you will stop and think {don't hurt yourself} about it an engine retarder would do no good with an auto, they have to have a tranny retarder.
Yes you did read your post, see the second quote.
Yes I do, the internet is full of guys like you.
LOL, You'd better stick to disco!!
Did you not read the artical on the brake saver or are you really that dense?
No I'm not, heavy construction epuipment have auto tranny's and if you will stop and think {don't hurt yourself} about it an engine retarder would do no good with an auto, they have to have a tranny retarder.
Yes you did read your post, see the second quote.
Yes I do, the internet is full of guys like you.
LOL, You'd better stick to disco!!
Wow toad, how long did it take for you to think of all this? Nothing better to do in life huh. Grow up dude, or should I say dudette.
06-25-2010, 09:08 PM
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Last edited by toad490; 06-25-2010 at 09:17 PM.
06-26-2010, 09:52 AM
#26
Administrator with a large ban hammer !
So far it just seems to be a heated discussion, i see nothing here that a little research can't settle... (goes back to listening to Donna Summer record)
06-26-2010, 07:03 PM
#27
Admin
Well said.... minus the Donna Summer record part (lol 
).
Everyone has different experiences that may not jive with what someone else has run across. Doesn't mean one person is more right than another, just means there is more out there that we have not seen/heard about.
).Everyone has different experiences that may not jive with what someone else has run across. Doesn't mean one person is more right than another, just means there is more out there that we have not seen/heard about.
06-27-2010, 12:59 PM
#28
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All I know about a Jake brake is I turn the switch on in my motohome and when I let off the go pedal the engine goes BURRRRRRRRRR and the bus slows down...
I could not tell you if it works on the tranny or the engine..... And really don't care as long as it works...
Looks like to me that both of you all know a hell of a lot more about this than I do... But one thing I can tell you is that I bet both of you are right in your statements..... My Grandfather told me once that its a mighty wide road that has only one lane...... So, using his logic I bet you both are right... Where I see a problem is the name calling and personel attacks... We can have dis-agreements and different opinions and that is what makes this forum so good.... Different experiences and opinions from us all... I suggest we keep the discussion on the subject and leave the name calling to the school kids while they are on their playground... JMO......
I could not tell you if it works on the tranny or the engine..... And really don't care as long as it works...
Looks like to me that both of you all know a hell of a lot more about this than I do... But one thing I can tell you is that I bet both of you are right in your statements..... My Grandfather told me once that its a mighty wide road that has only one lane...... So, using his logic I bet you both are right... Where I see a problem is the name calling and personel attacks... We can have dis-agreements and different opinions and that is what makes this forum so good.... Different experiences and opinions from us all... I suggest we keep the discussion on the subject and leave the name calling to the school kids while they are on their playground... JMO......
07-27-2010, 06:52 AM
#29
Wow, I just found this thread. I thought you guys only got this heated at me!
I don't know much of anything about Jake brakes so I did get some knowledge from this.
Hey Mr. 340, turn up the Donna Summers!
I don't know much of anything about Jake brakes so I did get some knowledge from this.
Hey Mr. 340, turn up the Donna Summers!
