Question for drivers in automatics

Discussion in 'Experienced Truckers' Advice' started by nmill, May 31, 2020.

  1. Brandt

    Brandt Road Train Member

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    Shifting gears down or up has no affect on slowing a truck. It not like car engine and it will slow you down. So shifting gear in automatic has no affect, if you not using any engine brake.

    People are forgetting if the trailer starts to slide and come around you and jackknife going downhill you have to apply power and pull the trailer. Because that's the only way to save yourself. That means with automatic transmission you don't want it in manual mode. Because you won't be able to pull the trailer without shifting gears manually. The automatic can shift gears faster and better in automatic mode. So your have a better chance of saving yourself and the truck and trailer
     
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  3. Trucking in Tennessee

    Trucking in Tennessee Road Train Member

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    Total BS. First, most companies disable manual shifting. The exhaust brakes on your modern trucks are amazing. They have 3 different levels. You will get slowed down.....safely. Now the old jakes...I have no idea. Fortunately I never had to use one of those noisy things.
     
  4. jammer910Z

    jammer910Z Road Train Member

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    Yes. Put it in manual if you can.
    If you leave it in Econ (IMO) it tends to over rev when it down shifts and I like to be in control.
    The key is to start down the hill at the correct speed and in the correct gear so you don't have to burn em up trying to get it under control.
    That Jake is your friend, but you need to know how to do it without it because someday you may have to in an emergency and that's no time to learn on the fly.

    Learn now.
    Do half a hill. Then put the Jake on and finish it.
    Use your opportunities to learn.
     
    T.Rucker Thanks this.
  5. mustang190

    mustang190 Road Train Member

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    Bottom line,,, get rid of the automatic.
    Never had those problems with that 13 or 18 speed stick. :cool:
     
  6. nredfor88

    nredfor88 Heavy Load Member

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    Just as important, or maybe more so, is the weight of the load when descending. A 45K load requires a lot more speed control than a 20K load.

    I drive a Cascadia with the Detroit DT12 that has the manual mode disabled, and I'm typically hauling heavy loads. I've found there are a couple options that have worked for me.

    If the conditions are really bad with snow and ice, the DT12 has descent mode. It holds the current gear and will not shift as long as the speed is below 30 MPH and RPMs are kept below 2200 and above 800. Then use snub braking as needed.

    If it's rainy or maybe some slush, but not bad enough to go below 30, there really is no choice but to use the jake setting 1, or maybe 2. Just need to be careful engaging it.

    An auto without manual mode in the winter mountains kind of sucks, but it's doable. It would be nice if there was a way to activate descent mode at a higher speed.
     
    nmill Thanks this.
  7. Trucking in Tennessee

    Trucking in Tennessee Road Train Member

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    I go down Mounteagle all the time. I can engage high braking (position 3) at 45 mph. It takes the RPM to 2200 but it will slow the truck down.
     
    D.Tibbitt Thanks this.
  8. Brandt

    Brandt Road Train Member

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    You can use Descent mode at any speed on the DT-12. That's what so nice you can go downhill even faster then old manual transmission if you let the computers do their job and bring the RPMs to 2200.

    Running the engine brake in snow or ice or slipper roads is bad idea. Remember the differentials will put all that engine brake power to tires with the least amount of tracking. Once you make the tires spin or lose traction. That set of tires will want to lead and come to the front. So your starting your own jackknife. Your better off no engine brake and using the regular brakes.
     
    Flankenfurter Thanks this.
  9. nmill

    nmill Light Load Member

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    Just to let you guys know I'm in a manual now doing local in a very flat area, I was just wondering. Thanks for the replies.
     
  10. nredfor88

    nredfor88 Heavy Load Member

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    Yeah, I use 3 as well in the rain. I generalized to much and was thinking of the slipperier conditions.

    Every condition requires an appropriate response with speed, jake use, and braking. These are learned reactions.
     
  11. nredfor88

    nredfor88 Heavy Load Member

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    I was not aware it can be used at any speed. Is that a programming option that companies change? I’ll give it some experimentation.
     
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