Page 3 of 8 FirstFirst 12345 ... LastLast
Results 21 to 30 of 78

Thread: Alison Tranny Retarder vs Jake Brake

  1. #21
    Join Date
    Jan 2006
    Location
    Jasper
    Posts
    3,775

    Default

    Peter,

    Marathon must have changed the jake/brake light in the later years. Mine does not operate the brake light and works with cruise control as well.

  2. #22
    Join Date
    Nov 2006
    Location
    Menifee California
    Posts
    994

    Default Brake lights / jake lights

    Tom, my brakes lights come on with the jakes, at least the light on the trailer brake controller comes on, so I assume the brake lights are on!

  3. #23
    Petervs Guest

    Default

    Quote Originally Posted by truk4u View Post
    Peter,

    Marathon must have changed the jake/brake light in the later years. Mine does not operate the brake light and works with cruise control as well.
    Thanks for the further info. My bus has the DDEC II system, and it is not sophisticated enough to allow user programming of the Jake Brake with cruise control, but the later DDEC III and IV are. You just hook up the reader box and set on or off with cruise control as you prefer.

    That points out the one deficiency I see with my set up, while toolig down the interstate and you start descending a little, well, the bus just picks up speed like a ball bearing rolling down a ski jump and before you know it you are doing 85. So, you have to stay alert and kill the cruise on a big downhill. That can be a pain if you are in a place like Interstate 5 in southern Oregon where there are a long series of 10 miles up hill followed by 10 miles downhill. But, clearly, Prevost addressed that on the later busses. Not enough reason to convince me to trade up though.

  4. #24
    Join Date
    Nov 2006
    Location
    Sugar Land, TX
    Posts
    1,307

    Default

    Thanks again guys for all the important information about Jakes and Retarders. I can honestly say I am only half as confused as I was half a week ago. (just kidding)

    Thanks for the info.

    Gary

  5. #25
    Stelan73 Guest

    Default

    Quote Originally Posted by Petervs View Post
    A quick review:

    The bus is moving at some speed and you want to slow down. There are 3 common ways to do this:

    A. The service brakes convert the kinetic energy to heat into the brake hardware by friction of the pads or shoes against the discs or drums.

    B. A Jake brake uses the kinetic energy to compress air, which is then "wasted" out the exhaust system. No heat is generated.

    C. A transmission retarder converts the kinetic energy to heat inside the transmission. The heat must then be removed by the transmission oil cooler. The cooler is a small "radiator" mounted in front of the big radiator and the transmission fluid needs to pass through here a time or two to cool off the transmission, which will take a few minutes or more depending on the outside temperatures and heat load on the transmission.

    All three methods do slow down the bus. Method A and C will eventually reach the point where the heat added by slowing is greater than the heat dissipated by airflow. For a single stop in traffic all will work well. For lots of stops in traffic all will work well for a while, but eventually A and C will begin to reach their limits. For descending a long grade eventually A and C will overheat. B will just keep on working, leaving the service brakes fresh and cool.

    For these reasons I prefer the Jake Brake. Especially if you live and travel mostly in the western states, almost anywhere you go you encounter mountain roads and passes. Knowing the Jake is ready to manage downhill speeds without needing the service brakes at all times is very comforting. You can select most any downhill speed by choosing the gear and setting the Jake on high or low. It is easy, effective, and the system has been trouble free.

    Then there is the issue of some towns and their signs about compression brakes. I have noticed the wording of these signs varies from place to place. Some I have seen say "Unmuffled Compression Brakes Prohibited" , or " Jake Brakes Unlawful in city limits", "Use of Engine Brakes Prohibited" or some such.

    I take the approach that in any kind of emergency, I will use all the braking systems I have no matter the signs in the area. Also, since the Prevost installation IS a muffled engine brake, it is not nearly so loud as what we typically heard on logging trucks, etc in the 1970's when the Jake Brakes came into common use and many of these signs sprang up. I have never heard of anyone getting stopped or ticketed for using the Jake Brake, but I would like to know if it has happened. Anyone?

    Another interesting point, on my 94 the brake taillights come on when the jake brake is working, and when you step on the service brake pedal, the red light on the dash also comes on to indicate that. So, someone behind you might think you are riding the brakes all the way down a long hill when actually you might not have touched them at all. And if you are decelerating into a town that has several speed reductions as you come to the center, while the Jake is working any local policeman will see that you are slowing down and not ignoring his speed limit on purpose. SO far I have never been stopped for that either, and wear and tear on service brakes can be minimized.

    One further note, I have driven both a Series 60 Detroit bus ( mine) and a 8V92 Detroit bus. The Jake effectiveness was noticably more in the Series 60 version when the setting on both was on High.

    As always, comments welcome!

    Peter vS
    94 Marathon XLV

    Peter: Most of the posts I have read are pro jake. If the jake system is preferred by most, why did Prevost go the retarder route on new shells?

  6. #26
    Petervs Guest

    Default

    Quote Originally Posted by Stelan73 View Post
    Peter: Most of the posts I have read are pro jake. If the jake system is preferred by most, why did Prevost go the retarder route on new shells?
    According to the Prevost website, both the Jake brake and the retarder are options on their shells. You can get them either way. I suspect the Jake brake costs more as a factory option.

    http://www.prevostcar.com/cgi-bin/pa...tab=powertrain

    I personally also prefer the Jake brake. Might be nice to have both! The only downside would be cost.

    Peter vS
    94 Marathon XLV

  7. #27
    Join Date
    Jan 2006
    Location
    anytown
    Posts
    8,908

    Default

    I too question why a retarder would be used in place of a Jake.

    It is abundantly clear by the maintenance schedule that Allison considers a retarder equipped transmission so hard on the fluids that change intervals are cut in half.

    There is a real plus for the Jake. When our granson was little when he travelled with us and we went through tunnels he loved hearing the sound of the Jake. He thought that was great.

  8. #28
    dreadnought Guest

    Default

    See my earlier post. The retarder costs more, much more.
    And Peter, The Jake on my Peterbilt is hooked to the cruise. If it can't hold the set cruise speed on a down grade the 1st stage comes on, if that doesn't do the trick the second stage and then the 3rd if needed. All automatically, with no driver input. Towns put up no Jake signs cause Grandma got tired of being blasted out of the bed at 2 AM by "chicken trucks" with straight pipes. My truck has 8" pipes with no mufflers but I've never had a problem cause I know when to behave. Jacobs Engine Brakes have been around for billyuns and billyuns of miles and work, period. I'm telling you, this is all a plot cooked up by Allison to sell trannys.

  9. #29
    Petervs Guest

    Default

    Quote Originally Posted by dreadnought View Post
    See my earlier post. The retarder costs more, much more.
    And Peter, The Jake on my Peterbilt is hooked to the cruise. If it can't hold the set cruise speed on a down grade the 1st stage comes on, if that doesn't do the trick the second stage and then the 3rd if needed. All automatically, with no driver input. Towns put up no Jake signs cause Grandma got tired of being blasted out of the bed at 2 AM by "chicken trucks" with straight pipes. My truck has 8" pipes with no mufflers but I've never had a problem cause I know when to behave. Jacobs Engine Brakes have been around for billyuns and billyuns of miles and work, period. I'm telling you, this is all a plot cooked up by Allison to sell trannys.
    Sure, I agree, but I bet your Peterbuilt is newer than my 1994 with a DDEC II. The later ones do it your way and that would be a great feature to have. But like I said, I do not think I will change coaches for just that.

    Peter VS

  10. #30
    Join Date
    Jan 2006
    Location
    anytown
    Posts
    8,908

    Default

    It seems clear we would like to have a Jake instead of a retarder, but there is a downside to the Jake that nobody has mentioned yet. A Jake works best at higher RPM.

    One thing I have noticed with the retarder is that when it is on and I hit the brakes the retarder aids in stopping power to a noticeable degree. With the Jake, when we got down below about 20 it dropped out and while it wasn't like the coach accelerated, there was a noticeable loss of stopping assistance.

    I guess if it could be done Perter's idea of having both would be the ideal.

Similar Threads

  1. Jake Brake / Trans Retarder
    By utahcamera in forum NEW MEMBER INTRODUCTION
    Replies: 26
    Last Post: 02-17-2013, 07:21 AM
  2. JAKE BRAKE
    By Woody in forum Busted Knuckles and Greasy Jeans
    Replies: 17
    Last Post: 12-05-2009, 06:45 PM
  3. Tranny Trouble
    By bonhall41 in forum Engines, transmissions, axles and wheels
    Replies: 21
    Last Post: 09-05-2008, 03:40 PM
  4. New ZF Tranny Controls
    By Just Plain Jeff in forum Quirks and little known Prevost Information
    Replies: 0
    Last Post: 12-22-2007, 06:03 AM
  5. Jake Brake?
    By rfoster in forum Prevost Shells and Prevost Car Company
    Replies: 7
    Last Post: 06-16-2006, 11:58 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •