How much does an empty 3-axle Mack Kentucky coal truck weigh?

Discussion in 'Tanker, Bulk and Dump Trucking Forum' started by Mike Murphy, Jun 19, 2017.

  1. Mike Murphy

    Mike Murphy Bobtail Member

    Apr 28, 2014
    Hello -

    By way of introduction, I am a research engineer at the University of Texas - Center for Transportation Research. I have posted questions on the Truckers Forum before and have received very helpful information. This past legislative session, 2 new truck size and weight bills were passed increasing international ocean shipping container truck and milk tank truck Gross Vehicle Weights using information provided by our research team to the State Legislators sponsoring these bills.

    I now am working on a question regarding 'drag force' which is related to truck skid distance and pavement roughness (friction). Drag force (measured when the pavement is dry) is not the measurement that a pavement engineer typically uses when determining whether pavements have enough roughness for the volume and types of traffic being carried on a given route - we used Skid Number which is measured by a skid truck and trailer which conducts testing by spraying water on the pavement and then locking the test tire. Thus, Skid Number is related to wet pavement conditions whereas Drag Force is used by law enforcement and others and is based on dry weather conditions.

    Sorry for all the details, but now to my question: I have been reading research conducted using various types of vocational trucks including a Kentucky 3-axle coal truck. The report provides skid distances at different truck Gross Vehicle Weights including empty weight (though no number was actually given) and loaded weights: 57,840 lbs, 98,280 lbs and 120,680 lbs. However, again, no number was given for the empty weight. This is a Mack, 3-axle coal truck - can someone give me an idea of the typical empty weight of this type truck? I am surprised that a 3-axle truck can carry up to 120,680 lbs - the report indicates that the manufacturer's allowable axle weight specs were 20,000 lbs steer axle, 65,000 lbs tandem axle.

    Any help you can give will be appreciated.

    Thanks very much,
    Mike Murphy
    University of Texas at Austin
    Center for Transportation Research
  2. cnsper

    cnsper Road Train Member

    Feb 28, 2014
    No idea but I want to say t he Western Star 6900 runs 80-85k empty.
  3. passingthru69

    passingthru69 Road Train Member

    Hope someone can help him
    I remember back on some things he posted about. He is kinda on our side guys on weights and measure issues.
    Hope you get your answer.
    Mike, try a Google search for a coal hauling company in W.Va or Ky.
    After they laugh, tell them you are for real and they might be able to help you.
    Alot will factor on the size of the dump body and if Aluminum or Steel box
    Length of the unit etc.
    Again good luck in your research
  4. Cat sdp

    Cat sdp . .

    Apr 8, 2012
    Orion's Belt
    I would guess 40,000 maybe..., box might be aluminum but the truck is gonna be heavy spec on steroids..,

    Hope someone can give you a real answer
  5. BKLusk64

    BKLusk64 Light Load Member

    Nov 17, 2012
    KY, WV and VA coal haulers always loaded more that the GVWR of the trucks. I think the typical 3 axle coal trucks were mainly set up for off road, but did see some on highway travel. Most were geared to run out top speed of 50 to 60 mph, with some being slower. As best i recall they were hauling 35 tons =+/-. If you need more information I can give you a contact at a Western Star dealer in WV.
  6. ErieMcDreary

    ErieMcDreary Light Load Member

    Dec 4, 2016
    Erie PA
    I'll try to help out, but a call to KY DOT might be able to answer more questions, especially if you can talk to an older or retired trooper, or someone who used to drive one. You could try Hanks Truck Forum, it seems a lot of older drivers are on there.
    Here's the laws 603 KAR 5:066. Weight (mass) limits for trucks.
    It seems you're refering to highway trucks, but I believe those extreme weights are no longer legal. The 65,000 rear axle weights you cited are per axle, total of 130,000 plus 20,000 front, but coal OWNED the state legislature for decades, law enforcement looked the other way and allowed them to run very heavy. They also used much larger, heavier duty tires, which will alter your skid resistance. The 40,000 empty weight is probably pretty close, they were built very heavy, and the Mack model# is DM800. Up here in PA, tri-axle (actually 4 axle) trucks are allowed to weigh 73,280, and typically haul about 46,000, so empty weight is around 27,000, but those are light duty trucks compared to those coalbuckets.
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