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Sooner_Schooner's avatar
Sooner_Schooner
Explorer
Apr 16, 2019

Allison Transmission Question

I'm still confused what it means when your shift control panel has a reading like 6 5 or 6 4. I was climbing a steep grade and it downshifted to 2 4. What does that indicate? I figured I just had gears 1-6, It's an Allison 6 speed.
Class A
  • wolfe10's avatar
    wolfe10
    Explorer
    Apr 16, 2019
    Correct.

    But when climbing (i.e. on the throttle) it will never read 2 4. If you are NOT on the throttle and have the exhaust brake ON and have a 2nd gear pre-select (the gear the transmission sifts toward with the exhaust brake on) that is reasonable.

    It means the transmission will continue to downshift until it reaches second gear and will do so as soon as it can downshift a gear at a time without overspeeding the engine.
  • Sooner_Schooner's avatar
    Sooner_Schooner
    Explorer
    Apr 16, 2019
    Ava wrote:
    The right number is the gear you are currently in. The left number is the gear the trans is heading for. When accelerating the numbers will read from 6 - 1 to 6 - 6. With foot off pedal the trans display will be the same. Left number is the gear it is heading for and right number is the gear you are actually in.


    Thank you sir, that clears it up.
  • Ava's avatar
    Ava
    Explorer
    Apr 16, 2019
    The right number is the gear you are currently in. The left number is the gear the trans is heading for. When accelerating the numbers will read from 6 - 1 to 6 - 6. With foot off pedal the trans display will be the same. Left number is the gear it is heading for and right number is the gear you are actually in.

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