Downshifting without revving up the engine?

Discussion in 'Experienced Truckers' Advice' started by expedite_it, Oct 28, 2021.

  1. expedite_it

    expedite_it Medium Load Member

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    Even though I have 7 years of trucking experience, I recently had to go out in a truck with a trainer because I started a job at a new trucking company. My trainer at my new trucking company is named Ed. Ed has a truck with a standard transmission. I asked Ed how much RPM's I need to rev up the truck's engine on a downshift. Ed responded that he does not rev up the engine at all on a downshift. He just said that he downshifts at 1100 RPM's without revving up the engine. During my trainer's shift, I noticed that he does indeed downshift without revving up the engine. When my trainer downshifted without revving up the engine, he did not grind the gears. I should have paid more attention to the cadence of Ed's downshifts.

    When I was first trained on how to drive a semi-truck with a standard transmission, my trainer's name was/is Keith. Keith taught me that i can start a downshift at any RPMs, but I just have to rev up the engine 400 RPM's more than whatever the RPM's were when I started the downshift. When I did team driving on trucks with standard transmissions, all my teammates would rev up the engine when doing a downshift. Keith, me, and my teammates could all downshift while revving up the engine without grinding the gears. However, when I tried to downshift the way that Ed downshifted (without revving up the engine), I would grind the gears badly and fail to get the truck into the lower gear. Another thing that I noticed is that when Ed slowed down, Ed would not downshift from one gear to the next like I do. If I am in 10th gear and if I need to slow down, I will downshift from 10th to 9th to 8th to 7th to 6th and so on until I get to 3rd gear or have to put my foot on the clutch and stop. Ed would skip many gears when he downshifted. Ed might downshift from 10th gear to 6th gear.

    Are you all familiar with the technique of downshifting without revving up the engine?

    I know that a lot of drivers nowadays drive automatics. However, if you drive a standard transmission, or if you used to drive a standard transmission, did you rev up the engine when you did a downshift?

    How was Ed able to downshift without revving up the engine?

    Was Ed able to downshift without revving up the engine BECAUSE he skipped gears when he downshifted? Is that how Ed was able to downshift without revving up the engine?

    If you downshift from, say, 10th to 9th gear without revving up the engine, do you have to shift faster than you would if you revved up the engine or slower than you would if you revved up the engine?
     
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  3. flightwatch

    flightwatch Road Train Member

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    Ummmm...that's impossible unless going uphill. You have to match the engine rpm to the lower gears rpm, or you'll grind...unless it's a synchronized transmission.
     
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  4. expedite_it

    expedite_it Medium Load Member

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    Ed downshifted without revving up the engine on flat ground. I saw it countless times with my own eyes. Well, Ed called it downshifting. Maybe what Ed was doing was not what you or me would call downshifting, but maybe what Ed was doing was gear recovery. Do you think that the fact that Ed was downshifting from 10th gear to, say, 6th gear would explain how Ed could "downshift" without revving up the engine?

    Or maybe it was a synchronized transmission, whatever that means.

    P.S. I think that the quote in your signature line was first spoken or written by Abraham Lincoln.
     
  5. special-k

    special-k Road Train Member

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    He was letting the truck slow down enough that the road speed matched the trans speed at idle. Practice it and you'll figure it out. Best way to practice it would be to pull it out of gear as your coasting up to a stop light and put it in low gear just as it's getting to the proper gear. It will fall into gear at idle around 5 mph. Practice it enough and you can do it at other speeds too. You have to know the speeds/rpm you go in all the gears though so it'll take time lol
     
  6. Cattleman84

    Cattleman84 Road Train Member

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    It sounds like he is double clutching... I cant do it that well but I have seen old timers do it without reving the engine at all.

    Here's a video...
     
  7. expedite_it

    expedite_it Medium Load Member

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    The transmission speed at idle is approximately 600 RPM's. He only slowed down until the RPM's reached 1100.
     
  8. God prefers Diesels

    God prefers Diesels Road Train Member

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    Beat me to it. I will sometimes kick it out of sixth, hit low range, and as soon as I get to 4mph, I can drop it right in third at idle. This is how you drive when you're too lazy to fix your range syncro, even after you bought said syncro a few months ago.
     
  9. Dave1837

    Dave1837 Heavy Load Member

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    Sounds like a synchronized trans. What kind of truck and transmission was it?
     
  10. God prefers Diesels

    God prefers Diesels Road Train Member

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    So he's in gear slowing down. Once he gets to 1,100 rpm, he's able to get it into the next lower gear without touching the throttle? If so, then as soon as he achieves gear mesh, does the engine jump several hundred RPM?

    One time I was shifting from 4th to 5th. (don't tell anyone I told you this, because it's embarrassing) Anyways, I accidentally pulled up the range selector right at the same time. Shifted from 4th to 10th, and it went in just as smooth as silk. What followed was not so smooth...
     
  11. OldeSkool

    OldeSkool Road Train Member

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    My question exactly. If the RPMs don’t go up, then the engine brake is worthless. So why would anyone do that?

    Most of us don’t admit what all happens during shifting, but thanks for the story. It made for a good laugh.
     
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