We just drove across the northern U.S. and we noticed that many heavy dump trucks have totally different axle arrangements than here in western Canada. Most dump trucks here have a single steering axle and two drive axles. Some trucks we saw south of the border had two additional carrying axles in the middle. Does this vary State to State? How much can single truck carry with this setup?
there are some 6 axle dump trucks down here ... I think they say 80,000# on the door most common is the standard 3 axle a few companies run 4 axles
In SC off the interstates a dumptruck is simple: 2 axles = 35,000 lbs gross 3 axles = 50,000 4 axles = 70,000 5 axles or more = 80,000 On the interstate we have to follow federal bridge formula, which is not simple
I am pretty sure there are 50 different weight rules for the 50 states. Federal bridge law is different yet.
I am not sure if all 50 states are different from the others but there are a lot of combinations. Illinois does not recognize lift axles of any kind. You run tandums or tractor trailer dumps. Here in Wisconsin the maximum GW for a quad axle dump which means two drives, two lift axles and one steer axle is 73,000 pounds. You have to have the right axle spread to do this also. We also have tri axle dumps which is two drives, one lift axle and one steer axle. Depending upon the spacing there gross is in the 64,500 pound range. Big problem there is if you load far enough foreword to have the drives legal the lift axle is over. Load far enough to the rear so the lift axle is legal and the drives are over.
Does that mean certain trucks are okay on local roads but illegal for the interstate?
Definitely, see my post #3
Sorry, I mean shouldn't a freeway be capable of handling heavier load than a city street?
It's Government, you'll only get a headache looking at it logicaly
My 200" wheelbase tractors with 24' trailers are legal for 80,000 lbs off the interstate in SC but only about 68,000 lbs on the interstate in SC, or anywhere in NC
It doesn't have anything to do with the actual road but with the bridges. Its called federal bridge law, and any roads funded by federal money like interstate highways have to comply. But a lot of states like the NW states, Washington, Oregon, Idaho, etc. have adopted the bridge law for all roads. If you go back east, you will se states that are grandfathered for one reason or another with all kinds of truck setups a lot heavier than what is allowed by bridge law. Link to the Washington State bridge law chart. http://www.wsdot.wa.gov/NR/rdonlyres/46A25D5A-FE56-46BE-AEC6-47CB4BEC072D/0/Legal_Weight.pdf And then there are states that allow or do not allow lift axles, etc. In the NW we are allowed up to 10,000 lbs per lift axle as long as the total setup does not exceed bridge law or tire weight limits. You go back east and you will see tri drive trucks instead of a tandem with a lift axle, etc. And then you have California which has another set of rules, which I still don't understand. For a dump and pup they usually are only setup for 80,000 with no lift axles while in the NW we can haul 105,500. The norm here used to be a 4 axle truck and a 4 axle pup, but this has changed the last few years to a 5 axle truck and a 3 axle pup.