Shifting with Jake brakes on.

Discussion in 'Ask An Owner Operator' started by D16, Mar 31, 2008.

  1. ziggystyles

    ziggystyles Road Train Member

    Well Im trying, but no matter how far I get my head in there, I still can't see things your way.
     
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  3. broncrider

    broncrider Road Train Member

    anyone here know what ears are for???
    they are handle pull yer head outta yer rear

    hopefully that is enuff directions for certian folks
     
  4. broncrider

    broncrider Road Train Member

    ziggy....

    if you are not pressing on the throttle, no fuel is being sent thru the injectors.....
    you see the injectors are a hydraulic/electric combo....a small seliniod gets input from the ecm, that got its signal from the long skinny pedel on the right


    hence no throttle pressure/ no fuel



    wheres that pete tech at???
    im sure his info will be much better than my half forgotton stuff
     
  5. MedicineMan

    MedicineMan Road Train Member

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    Woodville, TX
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    not to mention the engine fan turning on doesn't use fuel unles you are under load. In an engine braking situation it's creating more drag which helps slow things even more while the injectors are shut off. even on a mechanical you aren't using any more fuel then you would at an idle.
    that's my favorite one right there:biggrin_25521: (i love this new smiley too! lol)
     
  6. ziggystyles

    ziggystyles Road Train Member

    Correct me if Im wrong...but the diesel engines work on compression. Compressing the fuel, making it go boom and such, pushing the piston down, creating a revolution. Even with no throttle being applied, fuel is going through the injectors to keep the engine running.
    Now I knwo when the jakes are on, the injector is turned off and doesnt toss out fuel into that cylinder...but the engine needs the fuel to stay running.
     
  7. broncrider

    broncrider Road Train Member

    i dont remember the exact way it was tought to me but basicly, as long as the wheels are turning and its in gear....the crankshaft wil continue to rotate at a speed matching the input shaft of the tranny, which matches the output shaft, in turn the drivelines and finaly tires ( geared down of course)

    and the jacobs system does work off compression, but it alters the exhuast valve timing to get maximum retardation

    no fuel is used at any time during commpression braking, until you hit the throttle
     
  8. scfanman

    scfanman Bobtail Member

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    Mar 31, 2008
    Fullerton,ca.
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    This correct.
    Also,because the compression is released at the top,any fuel present does not fire.
     
  9. Angrypntballr

    Angrypntballr Bobtail Member

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    Apr 17, 2008
    Hereford,Tx
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    Jakes Always sound better on cold winter nights! I love that noise!!!
     
  10. Angrypntballr

    Angrypntballr Bobtail Member

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    Apr 17, 2008
    Hereford,Tx
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    Especially with straights!!!
     
  11. drive55cat

    drive55cat Medium Load Member

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    Mar 3, 2007
    Pa
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    I dunno 'bout all this technical stuff but I do know that on a triaxle dump truck, the game is a lot different, after 'bout two weeks with this truck I have learned much more 'bout the truck engine operation in relation to the jakes. And it is faster learning 'cause it's local and a lot of stop and go, I used to wonder what guys meant when they said" watch your speed and listen to the sound of the engine". I have learned to shift much better, including downshifting, a common mistake I was making, if it don't drop in gear, get your RPM's up. It's not that so much as the speed you are going, as soon as I started watching the speed, instead of the tach, things improved right away. In this eight speed the only one I have a little trouble with is 5th to 4th. Jakes to slow down and be more effective, keep it in a lower gear and at higher RPM's, then when you let off the gas, it slows rapidly. I reccomend triaxle to all starting out as it gives you a better idea of how the whole system is designed to work.
     
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