Sliding Tandems

Discussion in 'Trucking Industry Regulations' started by et1231, Jun 17, 2007.

  1. Libertarian500

    Libertarian500 Light Load Member

    Jun 24, 2007
    Utah, for now
    Wal-Mart trailers (that we pick up) are always butt-heavy. I don't know what it is about their dock people, but I think they must get nervous at the end that they'll run out of space, so they jam everything on. I know they're always loaded right up to the doors too. Wiggy and I work for the same outfit and the Wally World loads we pick up are generally Sam's Club warehouse drops.
  2. DeputyDog

    DeputyDog Bobtail Member

    Oct 21, 2006
    I carry a piece of kids "sidewalk" chalk. When I need to move the tandems, Using the 250# per hole, or 400# per hole formula,depending on the spacing. I then mark the hole that the pin is in now, and under the pin on the tandem, the location of the pin. This is especially helpful when you stop and the pin is between holes. I then figure out how many holes I have to move, and mark the new hole. That way I don't have to count every time I get out to check. The chalk also works on the fifth wheel.
    I sure hope that helps.
  3. DeputyDog

    DeputyDog Bobtail Member

    Oct 21, 2006
    I know that that is a federal exception for the weight, BUT, are the individual states required to allow for the extra weight of the APU?

    I'm not sure that they are since this an "exception" and not a law change.

    Also, most states would strongly resent, and definitely resist, any federal attempt to overwrite the "local" authority. If anyone knows for sure, I would appreciate hearing from you.
  4. jlkklj777

    jlkklj777 20 Year Truckload Veteran

    Oct 1, 2007
    Duncannon, Pa
    A couple of tips I have not seen mentioned are the following;

    Line up the rear trailer axle with the freight inside the trailer. On a uniform load (meaning same product loaded the same front to back) should get you legal.

    Some trailer axles have the mudflaps attached to the back axle and you can use this as a visual guide as well, just line up the mudflaps with the rear of the freight.

    As for bridge laws the distances do vary from state to state but as was stated earlier 41' will get you through just about every state out there. To determine this the distance is measured from the King pin to the centerline of the rear trailer axle.

    Weight adjustments are different based upon the spacing of the holes and the manufacturer. For the trailers I pull the trailer holes equate to 250 lbs per hole and the sliding 5th wheel will adjust 500 lbs per notch.

    Many times there will be no-one around to help you slide your trailer tandem so I will give you some tips on how to "do it yourself" that may save you some time, aggravation, and pulled muscles in your back and shoulders.

    Many older trailers will bind up and make it almost impossible to pull the draw bar for the tandem slide. There is a tool sold in truckstops that is a spring loaded device that attaches to the side of the trailer, a spring with a hook on the end will attach to the draw bar, and the other end of the spring will have a chain attached to it. Pull the chain, stretching the coil spring, and lock the chain in the "draw" position. Then get back in the truck and rock the truck back and forth to break the pins free. The spring will pull the draw bar out simultabeously retracting the locking pins. Exit the cab and remove the device after locking the draw bar in the open, slide position. Then adjust your trailer as needed. Too much weight on the drives? Move the tandem forward to accept more weight. Too much weight on the trailer? Move the trailer tandem further back.

    By the way this tandem tool will cost about 30 bucks and can be seen at many truckstops usually beside metal draw bars for pulling 5th wheel pins.

    For adjusting your 5th wheel be sure to drop your landing gear, release your air slide (pull the pin manually if you do not have an air assist 5th wheel), leave your trailer brakes locked and take the tractor brake off. If you want more weight on the steer axle then back your tractor up (if the truck doesn't move try and rock it or drop your air bags). If you want less weight on the steer axle then pull the tractor forward. Remember each notch or hole will be around 500 lbs so be sure to take note of where you started and where you want to stop.

    BUZZSAW Light Load Member

    Dec 14, 2006

    AND DON"T forget to check the clearance between your tractor mudflaps & landing gear. I don't know how many times I have seen drivers slide their 5th wheel forward (toward the cab) , start off & rip the mudflaps & brackets:biggrin_2555: off their tractor !
  6. techdog68

    techdog68 Bobtail Member

    Apr 29, 2010
    Duluth Georgia
    W = the overall gross weight on any group of two or more consecutive axles to the nearest 500 pounds.
    L = the distance in feet between the outer axles of any group of two or more consecutive axles.
    N = the number of axles in the group under consideration.
    Federal law states that two or more consecutive axles may not exceed the weight computed by the Bridge Formula even though single axles, tandem axles, and gross vehicle weights are within legal limits. As a result, the axle group that includes the entire truck—sometimes called the "outer bridge" group—must comply with the Bridge Formula. Interior combinations of axles, such as the "tractor bridge" (axles 1, 2, and 3) and "trailer bridge" (axles 2, 3, 4, and 5) must also comply with weights computed by the Bridge Formula
    Single Axle: 20,000 pounds
    Tandem Axle: 34,000 pounds
    Gross Vehicle Weight: 80,000 pounds
    Overall vehicle length
    Max length from axle 1 to axle 5 =51'
    max length from axle 2 to axle 5 =35'
    max weight on steer axle 12000 lb
    max weight on axle 2-5 = 1700
    No federal length limit is imposed on most truck tractor-semitrailers operation on the National Network.

    Exception: On the National Network, combination vehicles (truck tractor plus semitrailer or trailer) designed and used specifically to carry automobiles or boats in specially designed racks may not exceed a maximum overall vehicle length of 65 feet, normal 5th wheel, or 75 feet w/ stinger

    Trailer length

    Federal law provides that no state may impose a length limitation of less than 48 feet (or longer if provided for by grandfather rights) on a semitrailer operating in any truck tractor-semitrailer combination on the National Network. (Note: A state may permit longer trailers to operate on its National Network highways.)

    Similarly, federal law provides that no state may impose a length limitation of less than 28 feet on a semitrailer or trailer operating in a truck tractor-semitrailer-trailer (twin-trailer) combination on the National Network.

    Vehicle width

    On the National Network, no state may impose a width limitation of more or less than 102 inches. Safety devices (e.g., mirrors, handholds) necessary for the safe and efficient operation of motor vehicles may not be included in the calculation of width.

    Vehicle height

    No federal vehicle height limit is imposed. State standards range from 13.6 feet to 14.6 feet.
  7. gearrat

    gearrat Light Load Member

    Jan 17, 2010
    #### ready this gave me a headache. i normally set my trailer at california set and i have not had any problems at all when i hit a scale.
  8. CondoCruiser

    CondoCruiser The Legend

    Apr 18, 2010
    Many drivers don't know the steer axle weights refer only to state and county roads. Federal highways it's 20,000 lbs in all states except for MD which is 20,000 or the tire rating which ever is lower. Most steer tires are rated at 6250 lbs each. I haven't slid my fifth wheel since I got me truck and preset it. My truck is heavy and I'm usually around 13,000 on my steers. With a good load it counters my steers down to below 12,000.

    I pull a reefer and if I have a questionable load, I usually don't extend 48ft on my 53ft trailer. I'll set the back of the last pallet about 6" past the center of the back axle. That'll get you pretty close for preweigh. My formula is stupid but it works and I never had to reweigh. I figure the difference from the front and back, divide by 2 and divide by 450 and I'm right on the money. Don't ask me why I don't divide by 900?? I created that formula a long time ago and stuck with it.
    Now I have a load pressure gauge and air slide, spoiled. I don't scale unless I load over 42000. If I'm heavy, I can slide the tandems in both extremes to see my total weight. If it's right, I'll use my mark and go on. I've checked the gauge several times and I'm either right on the mark or one hole off, so I feel compfortable with it now.

    APU's, I have a ThermoKing and we are allowed 400 lbs over with it. .
  9. SLCTrucker

    SLCTrucker Medium Load Member

    Jan 15, 2009
    Salt Lake City UT
    Most trucks are not rated for 13,000 on the steers. Is Yours?
    Mine front end is rated for 12,000 on the axle and tires are rated for 6,250 approx each . (cant remember exactly) but that seems to be the industry standard.
    Just because the state allows more than 12,000 on the steers if the trucks not rated for it, its a real bad idea.

    I see you said most steer tires are rated at 6,250 lbs, how does this allow 13,000 as the tire rating combined will only be 12,500?
    13,000 - 12,500 = 500 over tire rating and I really dont want to put on a axle not rated for it.
  10. CondoCruiser

    CondoCruiser The Legend

    Apr 18, 2010
    Doesn't matter. DOT doesn't care about ratings when it comes to scaling out except for MD. Have you ever seen a steer tire rated at 10,000 lbs? One of them gov't gliches. Haven't got a ticket yet :) You tires ain't gonna blow from 250 overweight each. Ratings are minimums to protect the manufacturer. I won't go over 13,000 and most times I'm around 11,500. Just pointing out the law.
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