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Getting Weighed

Discussion in 'Commercial Snow Removal' started by Mitragorz, Oct 18, 2016.

  1. Mitragorz

    Mitragorz Senior Member
    Messages: 227

    I'm interested to see what the weight is on each of my axles. I don't have a CAT scale or anything like that near me, where I can just drive on and get the readings. So I plan on going to the local scrap dealer, driving the front wheels on, get the weight, put the whole truck on to get total weight, then driving forward and leaving the rear wheels on to get the rear weight.

    The real question: I have a 2-yd spreader in the back, which is going to be unloaded. To get a better guess on the weight obviously I'd just add estimated salt weight to the total, but for the axles... The rear axle seems to be pretty much centered in the bed, biased a little bit towards the front. So maybe a 90/10 weight split towards the rear to get a good final guesstimate? Maybe counted it fully on the rear axle, with the gas spreader motor hanging off the back?

    The truck is a '97 F250HD extended cab, long bed.

    This is the kind of stuff that I think about when I'm stuck in a hotel.
  2. JustJeff

    JustJeff 2000 Club Member
    Messages: 2,243

    There are a lot of words there, but I guess I don't really understand what your question is.
  3. Mitragorz

    Mitragorz Senior Member
    Messages: 227

    The question is about compensating for weighing the truck with an empty spreader as opposed to a full one. I'll have my "empty" axle weights. Figuring my "loaded" axle weight with, say 3000lb in the spreader. Add 500/2500 front/rear? 1000/2000? 0/3000 since the axle is a hair forward of the center of the bed?
  4. seville009

    seville009 Senior Member
    from CNY
    Messages: 801

    It's definitely not going to be zero on the front axle, as the front axle will always carry some of the load. I have no idea how you would compute it, but you're probably not too far off with your 1000/2000 estimate. May be a little less than 1000.
  5. Mitragorz

    Mitragorz Senior Member
    Messages: 227

    For 3,000# it actually would be 100/0 rear/front. You can check my math to see if I screwed something up. It must be because adding that weight moves the truck's CG aft of the midpoint of the wheelbase, essentially lifting the front end.

    I got the truck weighed for $10 at the local scrap yard:

    Front Axle: 5,080# (already over the 4,800# max)
    Rear Axle: 3,180#
    Gross: 8,260#.

    With those numbers, I figured out the CG: 5,080# is 62% of 8,260#, and 3,180# is 38%. That means that at this weight, 62% of the weight is over the front axle and 38% is over the rear. 38% of 155" is 59", meaning that the CG is 59" aft of the front axle.

    I then used simple weight and balance calculations and added 3,000# to an arm of 157" aft of the front wheel (the center of the bed is 148" aft of the front wheel, plus 9" that the spreader sits back from the front wall of the bed) and calculated a new CG of 85". 85" is 55% of 155", meaning that 55% of the weight is now over the rear axle, and 45" over the front. Multiplying those percentages by 11,260# (the new gross weight) gives a rear axle weight of 6,193# and front axle weight of 5,067# Note that the front weight actually DECREASES by 13#.

    Compare 6,193# to the old rear axle weight of 3,180, and you get a difference of 3,013#. Now compare that against the weight added (3000#) and you get 100.4%. Yes, adding the 3,000# actually resulted in a 3,013# increase to the rear (lever effect).

    Compare 5,067 to the old front axle weight of 5,080# and you get a difference of -13#. Compare that to the added weight of 3,000# and you get an increase of -0.4%.

    In conclusion: Of the 3,000# added to the bed, 100.4% was distributed to the rear axle, and -0.4% was distributed to the front.

    Here's the work. It won't let me load attach the PDFs, so here they are in link form:


    The first link is the figuring of the beginning CG.

    The second link is calculating the new CG after adding the weight, and the subsequent calculations to come up with the weight distribution.
  6. Mitragorz

    Mitragorz Senior Member
    Messages: 227

    That last part is incorrect, I think, but I can't edit the post now. The reason the front lifts is because the weight is actually being added aft of the rear axle, albeit only 2". That's what causes the front end to lighten.
  7. SnoFarmer

    SnoFarmer PlowSite Fanatic
    from N,E. MN
    Messages: 9,463

    ktfbgb and FredG like this.
  8. Ramairfreak98ss

    Ramairfreak98ss PlowSite.com Addict
    Messages: 1,930

    Its really hard to "guess" without weighing with the salt.. One of our F550s had a 4 yard salt dog spreader, the FRONT of the spreader barely touched the front portion of the rear axle tires, so MOST of that amount of weight was BEHIND the axle, on a 200" wb truck, it literally felt like it took a TON of weight off the front axle, made it feel unsafe almost. We put that spreader in a newer 9' mason dump F550 and it sits almost centered on the rear axle and drives great. We switched to a new MDX 4.5 yard swenson electric spreader "i know its bigger/heavier", but its 10.5' long, so its like 3ft MORE in front of the rear axle than the other spreader was. Loaded its now way more even, still not sure if it adds any weight to front axle but at least its not taking weight off.

    I've weighted two F550s recently on scale at mulch/soil yard in and out.

    2007 crew cab 12' landscape body steel, 12,350 in "empty load" , 5960lbs front axle, so 6,390 on the back, hopefully is 5,000 when i get a replacement aluminum body installed in the spring. When i leave with 5 yards or dirt/7 yards of mulch etc. with a total weight of anywhere between 18,000-22,000 " i know its 2k over there", the front axle still scales at 5,900-6,600lbs, depending on how forward the load is piled or if piled too far to back etc. Most of these trucks ALL the payload weight is on the rear axle, very little, if any is added to the front. The rear axle is rated for 13,500 i think and i have summer upgraded goodyear 245/70/19.5 tires that hold an additional 800lbs per tire over stock. Winter time i'm sure we're always over fully loaded and with plow, but its cold out and tires can't heat up much even loaded too much. Make sure to run enough PSI too.
  9. Dogplow Dodge

    Dogplow Dodge PlowSite Veteran
    from NJ
    Messages: 3,511

    Ok, no a that you've done all the calculations, what is it that you've achieved in doing so. ? Not trying to be a smart arse, just wondering what all this brain exercises are going to achieve in the end. What is your conclusion, and how will you apply it to your ride.?
  10. FredG

    FredG 2000 Club Member
    Messages: 2,722

    Make sure your DOT #'s are very visible. If you look safe and aren't sagging like some :terribletowel:you probably won't have any issues. I'm not sure what info. you are looking for. Your max GVW is what DOT is concerned with. I got pulled because I was going a short distance and did not have a chain on the excavator boom. :hammerhead:

    My DOT #'s were cut to fit on my 2 front fenders. While I was pulled the cop was going to write me a ticket for no DOT #'s. These #'s are very visible. Get my point?
  11. ktfbgb

    ktfbgb PlowSite.com Addict
    Messages: 1,662

    Man you guys really have it rough. This is all stuff that no out ever has to deal with. Literally. I have never seen, heard, or experienced anyone out here ever being pulled over for weight or proper securing of payload etc. I mean you should see what some of the land scapers and fire wood guys do with their trucks. Like literally front tires bouncing down the road. The cop will wave as they go by if they know them. If you loose something off a trailer load the cops will help you get it off the road and say he next time try thinking about securing stuff better. I couldn't imagine being throat crushed by jack boot cops and over legislation of everything in my life on a daily basis like you guys have to deal with.
  12. FredG

    FredG 2000 Club Member
    Messages: 2,722

    It's all about the Moneys, I would never overload my dumps, The fines are deadly to your money. I will close one eye to a salt truck as long as I look safe. Time to time they got state police in vans with scales and point you in a lot and weight you. Sometimes depending how your truck looks they been known to pull a wheel. They will usually let loaded pickups pass tho.
  13. Mitragorz

    Mitragorz Senior Member
    Messages: 227

    This wasn't for the DOT at all, this was just for my own info.

    I knew that I was closing in on the max front axle weight of 4800#. I wanted to figure out approx. what the truck would be at with 3/4 load of salt in the back. I'm over by about 300#, but that's with a 9' Pro Plus with wings. My regular 8' Pro Plow would keep me just under max front axle weight.

    I already knew that I would be over max GVW (I know, lock me up and throw away the key...) but 2500# over is a little much.

    What did I learn? A bigger truck is in order.
    ktfbgb likes this.