Lift axle size and spacing help....

Discussion in 'Ask An Owner Operator' started by baselp82, Dec 4, 2018.

  1. baselp82

    baselp82 Bobtail Member

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    Hey everyone! So hopefully someone can help me out on my current lift axle setup and possibly changing it to better fit my carrying capacity needs on a 26ft straight truck, I have plenty of GVW room on the truck but I am limited in hauling capacity due to bridge laws. I cant seem to find the answers I need anywhere else.

    My current lift axle is a 20,000# axle with a spacing of 9' from center of rear axle on tandems to center of lift axle for a carrying capacity of 42,500#

    I have two questions...

    (1) is my lift axle too big? Can I get away with a smaller capacity axle? My current one is super heavy!

    (2) can I move my lift axle forward for a spacing of 14' for a carrying capacity of 46,500#?

    Thanks in advance!
     
  2. I glide 47

    I glide 47 Heavy Load Member

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    I am not knowing. Interesting question though ,best of luck.
     
    Nothereoften Thanks this.
  3. dirthaller

    dirthaller Medium Load Member

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    Too many variables here. What state(s) are you running in? Is your load divisible or non-divisible?How do you know how heavy your lift axle really is?
    If you’re attempting to bridge #46,500 in 14’, most places I’ve been, will make you have no more than #34,000 of that on your tandems anyway, so, unless it’s loaded perfectly, that gives you no wiggle room on...... say....a #12,000 lift axle.
    I have a hard time believing that a #20,000 non steerable axle is much heavier than a #12,000 steerable.
    Also consider physics. I had a 224” wheelbase Kenworth T800 with the lift mounted @ 9’2” which put me in a 10’ bridge (#43,500). My 260” wheelbase Peterbilt 379 EXHD had the lift axle mounted the same (9’2”). I could pick the weight off the steer axle of the Kenworth by simply adding air pressure to the lift axle. On the pete, it would pick all the weight off the drives.
     
  4. dirthaller

    dirthaller Medium Load Member

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  5. baselp82

    baselp82 Bobtail Member

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    Thanks for the info to consider, and nice rig! I currently run Ohio, PA, and sometimes MI and WV. I haul plate that is almost always 8'x20' so not a lot of room to move the material around on the bed. Honestly not sure how heavy my lift is but compared to other lift axles I see mine is vastly larger and beefier but the weight difference may not be that much. Also my wheel base is 309" I'm really just trying to add another 4000lbs of carrying capacity to get me closer to my gross and it opens a lot of doors for load availability around me. If you know any other ways to do so I'm all ears! Thanks again!
     
  6. dirthaller

    dirthaller Medium Load Member

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    309” center of axle to center of axle? Or 309” wheelbase? The difference is about 27” between the two.
    Either way, you can’t gross more than 60,500 on the whole vehicle, no matter where the axle is located.
    Going from a 12,000 rated steer axle to a 20,000 steer axle will benefit more than the rating or location of a lift axle.
     
  7. dirthaller

    dirthaller Medium Load Member

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    What’s your steer axle rated for?
    Does 60,000 get you where you need to be if you can correct your axle weight/ inner bridge problem?
    What’s the tare weight of your truck?
    How about a photo of this truck?
     
  8. baselp82

    baselp82 Bobtail Member

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    First thanks for the help so far! Here is some more info on the truck and a pic.

    Front axle is a 20k axle, 309" wheelbase is from center of front axle to center of tandems (327" from center of front axle to center of rear axle) GVW on the truck is 66k, empty weight of truck is 27,840lbs. I would like to be able to carry around 38k of payload. I believe with my current setup 34k is my max payload.
     

    Attached Files:

    Ruthless Thanks this.
  9. dirthaller

    dirthaller Medium Load Member

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    Unless the states you run in have different, “grandfathered” (before 1975) bridge laws, you’re stuck.
    You need a longer truck or a lighter truck.
    Moving your lift axle is just going to allow you to axle out the payload you already have easier.
    Those steer tires don’t look like they’re rated for 20,000.
    Unless I’m missing something, your setup looks like it can barely gross 62,500 and that’s with 20,000 worth of rubber on the steers.
    I’d say that in order to gross the 64,000 that you claim, you’d have to move your lift axle forward and get bigger steer tires.
     
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