Coasting trucks, what's the point??

Discussion in 'Motor Carrier Questions - The Inside Scoop' started by Dave1837, May 9, 2021.

  1. Dave1837

    Dave1837 Road Train Member

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    Lately this has became a pet peeve of mine, trucks coasting downhill. Pass them going up, they ride side by side with you going down so you slow down and get behind them, THEN THEY SLOW DOWN!! My question is, does it really make a difference coasting in neutral down a hill as opposed to coasting in gear? Or coasting at 650 RPMs as opposed to 1500? I can't see the difference being that extreme as there is no load on the engine either way
     
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  3. Judge

    Judge Road Train Member

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    Call the companies, that’s the way the auto shifts are programmed, they’ll let off the pedal near the top, and gain speed on the downhill side.
    Call all major truck manufacturers first, then all major companies second and let them know how you feel about their system/trucks.
     
  4. Doealex

    Doealex Medium Load Member

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    My guess is it could be a new eco feature in newer auto trans trucks. One of my 15 Volvo trucks has eco-roll auto transmission; when cruise control with eco-roll active after rolling for a few seconds computer switches transmission to neutral, leaving the super quiet cab completely quiet. Scared me the first time I used it; I don't use it because I think it will lead to premature wear of the transmission; few cents savings on fuel are not worth it to me. Besides, I don't use cruise control driving through hills. Drivers who use it probably trying to get fuel savings bonuses, mega trucking companies like it because they will dump their trucks as soon as the transmission warranty expires, and they need those tiny fuel savings to show their investors how fuel efficient their fleet is in order to fleece them even more.
     
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  5. Dave1837

    Dave1837 Road Train Member

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    Yeah, I'll get right on that LOL!!
     
  6. Judge

    Judge Road Train Member

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    I’ll quote this.
    653790C5-2804-48B1-BC01-DFEF49DE5911.jpeg
     
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  7. Dave1837

    Dave1837 Road Train Member

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    Unless that person is a truck driver, then your voice doesn't count
     
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  8. Doealex

    Doealex Medium Load Member

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    Or call Greta Thunberg, maybe you'll get your name mentioned in one of her featured tirades.
     
    Last edited: May 9, 2021
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  9. God prefers Diesels

    God prefers Diesels Road Train Member

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    Maybe they're trying to make a run at the next hill.
     
  10. AModelCat

    AModelCat Road Train Member

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    Logic says coasting at idle will burn more fuel than coasting in gear:

    Coasting in neutral, the injectors will be squirting in fuel to maintain idle RPM.

    Coasting in gear, no fuel should be injected. Desired RPM would be idle speed but the drivetrain will be pushing the engine, maintaining RPM above idle speed. The ECM wants the engine at the desired idle speed so it should not be injecting fuel.

    Only advantage I could see is if the gain in momentum from coasting helps you pull the next hill easier.
     
  11. God prefers Diesels

    God prefers Diesels Road Train Member

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    I'd think they'd save more money staying in gear and saving their service brakes. And what happens when the truck hits a speed high enough that the engine can no longer rev enough to achieve gear mesh? Does the computer decide to put it back in gear before that happens, or does the truck run away?
     
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