Auxiliary transmission for heavy haul?

Discussion in 'Heavy Haul Trucking Forum' started by S & W, Jul 13, 2022.

  1. S & W

    S & W Bobtail Member

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    I’m speccing a new truck and was wondering should I go with an auxiliary transmission. It would be a fabco/fatco 3 spd I believe. I’ll be grossing 170k Max . How would the auxiliary benefit me performance wise? How and when do you use them? Is it hard to learn to shift with them? I’m not sure I would actually need one but I would rather have it than to not have it later on should I decide to haul a 13 axle set up
     
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  3. idriveaholden

    idriveaholden Medium Load Member

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    at those weights I don’t think you would benefit or use more then 2 speed. I would still get one if it were me.
    Im not sure about that brand and have never seen anything other then 2 and 4 speeds.
    Just use it when your loaded pulling hills or in a bad lot or whatever at customers

    The lower settings will change your top speed so keep that in mind, and what gear to be in according to your speed will change from what you’re used to.
    I’ve only used a 2 speed a couple times we just got some trucks with them so I need to figure it out too .

    In general say with a 4 speed we would use 4 bobtail
    3 empty 2 loaded 1 for slow speed maneuvering in yards
    It can change with each trucks gearing, engine etc too tho.. and thats dealing with heavier weights
     
    Last edited: Jul 13, 2022
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  4. Oxbow

    Oxbow Road Train Member

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    I have no experience with modern aux. transmissions, just older 5x4 etc., but I do have 2 speed rears @5.29 and 4.1. They can be shifted while moving but typically not used to split gears consistently. As @idriveaholden mentioned they are good for soft ground conditions etc. as well as pulling hills. In the slower gear set they reduce the split of an 18 sp in speed and are generally easier on the drivetrain in tough conditions. I believe that @Rontonio has experience with aux trans in new trucks and perhaps he can shed some light on the benefits, but I would quiz your salesman about the cost and benefits of each as well.
     
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  5. REO6205

    REO6205 Trucker Forum STAFF Staff Member

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    Same here. I'd like to hear more about it. We've used the usual two stick set ups but I've never seen something like the OP describes.
     
  6. idriveaholden

    idriveaholden Medium Load Member

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    Any auxiliary I’ve used YOU CANNOT SHIFT DOWN WHILE MOVING!
    You will split the case in half , surprisingly I’ve seen it happen more then once…

    you can shift the air auxiliaries up while moving but there’s a trick to it and it’s still sketchy to me.
     
  7. REO6205

    REO6205 Trucker Forum STAFF Staff Member

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    Probably a dumb question but how does an auxiliary differ from just a regular browny? We tried out a couple of airshift brownies a few years ago but they were always too slow to shift. Two speed rear ends the same way...too slow and too fragile.
    We had our best luck with 6&4s and straight 18 speeds.
    A lot of our work is off-road.
     
  8. idriveaholden

    idriveaholden Medium Load Member

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    Im not sure. I think they’re the same thing. Just spicer makes most of them now
     
  9. baha

    baha Road Train Member

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    They work well with steep hills where your forced to stop, we had a 2 speed browne in the A/car we used to haul large houses on 2 I beams and when you were going to go to hi gear you were rolling 10 or 15mph and you had to pull the 3ft pipe shifter back fast or the boss was using 4 letter words walking in front telling you witch way to steer as you rolled close to a stop and dropped it into low and tried it again, l tried it with just the truck with the beams on roof rack but it shifted different pulling a house?
     
  10. kranky1

    kranky1 Road Train Member

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    Two of mine I had built with RTO15’s and I yoked 1241 auxiliaries with C ratio sets onto the back of them when they came in. That works ok. Just can’t use deep reduction with the a-box in first unless you have a spare power divider with you.
     
  11. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    Couple years ago I got a call to pull this trailer out of a holler here in WV, and take it to the Freightliner dealer where the truck that normally pulls it was towed to.

    If memory is correct the driver told me the truck had an 18 spd backed up with a 4 spd.

    He had came from out in California with it loaded. Trailer along was 78,000 lbs, and he had pulled it with over 125,000 lbs on it…. Trailer was 12’ wide & 105 feet long.

    I’d much rather have more gears than I need, than not enough when I needed them…..

    FE56DE0F-954D-4A80-82D5-95F3F74D83B0.png 3770B999-6D11-41A2-8588-B27FA95FFD93.png
     
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