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Thread: Mercedes gearbox settings

  1. #1
    Join Date
    Mar 2008
    Posts
    97

    Default Mercedes gearbox settings

    Hi,

    This is the gearbox control on my automatic Mercedes 1124 AF. As per the picture, I have a the black selector cog that I can turn for the three settings. Initially I had guessed that this was high (2 straight lines), neutral (oval), low(wavy lines) however I can drive equally in all three (so no neutral). The performance in each seems to be the same so doesn't feel like a high / low. I get an air sound when I move the selector between settings so feels like it is moving between them. It has separate controls for the centre and rear diff locks so not thinking its that. Any help appreciated.

    Merc gearbox control.jpg

    Cheers Tobias

  2. #2
    Join Date
    Mar 2008
    Posts
    97

    Default Second picture

    Close up picture

    Merc gearbox control 2.jpg

  3. #3
    Join Date
    Apr 2015
    Location
    Arizona
    Posts
    170
    Toby,

    I have the same in my 917. My manual says what you said. high, neutral, low. Myself, I've never played with it.
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  4. #4
    Join Date
    Oct 2006
    Location
    Anchorage, AK
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    1,381
    I'd guess the high is for flat terrain, the low for hilly terrain to keep it in lower gears longer.
    Charlie

  5. #5
    Join Date
    Feb 2010
    Location
    Essex UK
    Posts
    87
    Hi Toby
    I have the same selector in my 1017a. The two lines are 2 wheel drive. The wavy line is 4 wheel drive and the 0 is no drive which I guess is for when using PTO if you have it. You must only move this when stationary. It takes a few metres for the 4 wheel to kick in and a light on the dash confirms this.
    If you have normal drive in all three positions then I would suggest it's not working correctly. I would start with the air valve onder the cabin on the back of the switch.
    Neil

  6. #6
    Join Date
    Mar 2008
    Posts
    97
    Hi guys,

    thats great thank you. Makes more sense, will have a look why its not going in to neutral. Also haven't seen a light going on for 4x4 so wonder if it is actually engaging.

    Cheers Tobias

  7. #7
    Join Date
    Nov 2012
    Location
    Ontario Canada
    Posts
    669
    The straight lines are high
    oval neutral
    wavy low range
    The truck us full time 4 wheel drive as far as I know. (I have had the 917AF on the hoist changing a bearing, in high moving the input shaft feeds power to the front and rear)
    Sounds like you have a problem if the truck drives the same in all positions. You should have no drive in oval position and low range is very low.
    1993 Mercedes-Benz 917 AF

  8. #8
    Join Date
    Feb 2010
    Location
    Essex UK
    Posts
    87
    Hi Joe.
    My wavy line also selects 4 wheel drive, and lights up the 4wd lamp on the dash.
    I wasn't aware that the 917 was permenant 4wd. This surprises me .

    Toby. Is your vehicle 2 or 4wd or permenant 4wd. It would appear that this selector has slightly different functions depending on whether it's permenant 4wd.

    In my 4wd it lowers the ratio

    Neil
    Last edited by Neil; 07-09-2016 at 06:12 PM.

  9. #9
    Join Date
    Mar 2008
    Posts
    97
    Hi,

    I don't know for certain, I have no paperwork with the truck so figuring it out as I go along. I thought it was permanent 4x4 and certainly other 1124 AF 4x4s seem to be permanent. Looks like in all these scenarios the 0 should be neutral so the fact I still have drive when I'm on that setting is confusing.

    Cheers Tobias

  10. #10
    Join Date
    Feb 2010
    Location
    Essex UK
    Posts
    87
    Toby
    Firstly, the 0 setting is definitely " no drive " so if you have drive in this position it's not working . I would s!tart with the pneumatic valve on the underside of the switch.

    Secondly if your vehicle is 4wd only ( which would surprise me ) then it narrows you options of MOT stations as you can't use a rolling road so you need to check that they can measure the breaking in a different way.

    Joe The AF models were mainly used as fire engines so it really surprised me that yours is 4wd only as this tends to lower the ratio and make them slower. They were fitted with fast axles so that they could get to the fire quickly. It would appear to defeat the object by by trapping them in low ratio.

    I am not doubting the fact, it just surprised me . Note to self, never assume.

    My vehicle is described in the spec as 4x4 but is in fact both.

    Neil

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