over GVWR question
- Thread starter dancorn
- Start date
It's way more complicated than that. The stopping won't be linear, because the kinetic energy of the two weights will not be linear. Whether you are overweight or underweight is irrelevant, as the distance is inversely proportional (assuming all other things are equal, including the overweight vehicle's ability to properly perform when overweight). If the weight is the same but the speed increased, doubling the speed quadruples the stopping distance. The same is true for mass, where if the speed is the same and only the mass gets doubled, the stopping distance is also quadrupled.
When you go from 6000 pounds to 9000 pounds, and increase of 50%, your stopping distance doubles, or is 200%. If you go from 6000 pounds to 12,000 pounds, an increase of 100%, your stopping distance quadruples, or is 400%.
A weight increase of 7.5% is minimal with regards to stopping distance, and even without doing the math, it's in the additional 10% range, plus or minus 5% for the speeds we travel (between 30 MPH and 75 MPH, anyway). Because of the increased kinetic energy at high speeds, the higher speeds like 65MPH and above will be more closer to the 15% further range, and the lower the speeds below 45MPH and it'll be closer to the 5% range. But 10% across the board is not a bad think to keep in mind.
So, if it takes you three car lengths to stop at 60 MPH, then it'll take you 3.3 car lengths with the extra weight.
Distance to stop, d = 0.5 * mass * velocity^2 / F
But that doesn't take into account braking pressure applied by the driver, temperature and pressure of the tires, the kinetic coefficient of the road, whether the road grade is slightly up or down hill, stuff like that.
When you go from 6000 pounds to 9000 pounds, and increase of 50%, your stopping distance doubles, or is 200%. If you go from 6000 pounds to 12,000 pounds, an increase of 100%, your stopping distance quadruples, or is 400%.
A weight increase of 7.5% is minimal with regards to stopping distance, and even without doing the math, it's in the additional 10% range, plus or minus 5% for the speeds we travel (between 30 MPH and 75 MPH, anyway). Because of the increased kinetic energy at high speeds, the higher speeds like 65MPH and above will be more closer to the 15% further range, and the lower the speeds below 45MPH and it'll be closer to the 5% range. But 10% across the board is not a bad think to keep in mind.
So, if it takes you three car lengths to stop at 60 MPH, then it'll take you 3.3 car lengths with the extra weight.
Distance to stop, d = 0.5 * mass * velocity^2 / F
But that doesn't take into account braking pressure applied by the driver, temperature and pressure of the tires, the kinetic coefficient of the road, whether the road grade is slightly up or down hill, stuff like that.
chefdennis
Veteran Expediter
Aren't you glad youa sked!?!? One thing to keep in mind when posting here, we do have more then one intelliual geniuses (yea i had to lookk it up and it could be genii also) here...but good job Turtle!!
rodeojunkie
Seasoned Expediter
It also doesn't take into account the fact that the braking system probably cannot expel the extra heat generated by over working the brakes by trying to stop the over weight vehicle. If it is a one time stop, they won't retain as much heat but if is repeated stopping the brakes might not adequately cool down between applications.
Exactly. A tractor-trailer or a straight truck that's overweight by 700 pounds probably won't see much of a change in vehicle handling and performance, particularly by the brakes and suspension, but with a cargo van, 700 pounds over could change things dramatically.
rodeojunkie
Seasoned Expediter
Depending on the distribution of that extra weight it could have a drastic affect on the performance of the vehicle. When braking, the majority of the work is done by the front brakes and unless most of that excess weight is behind the rear axle it will amplify the affect on the front brakes. Why do you think car manufacturers try their best to get a 50/50 weight distribution in vehicles they produce?
shadow7663
Expert Expediter
Fantastic answer and it's 100% true. Exactly how I would have answered this question....
LOL. Everyone just calls us "dumb truck drivers"
nightcreacher
Veteran Expediter
We are dumb truck drivers.Being in a tractor trailer and taking a load that makes you 100 lbs over gross,or in a cv that makes you 100 lbs over gross.The fine for being over gross wont even come close to the little difference in revenue you have generated hauling that load.
Shadowpanda
Seasoned Expediter
Perhaps you have purely academic reasons for asking this. If not...well don't run heavy. Get yourself and everything you take on the road with you, fill the tanks, go scale. Subtract that from your GVWR and you know your useful payload, and there is then never an excuse for being heavy. Showing up at a DOT scale overweight is just asking for them to turn you upside down and shake you till they find something else wrong to write a ticket for also.
In 10 years NEVER....not even a roadside...nothing...
60MPH
Expert Expediter
In some states it is not so bad like Va. It is only .05 cents a pound plus 25.00 civil fee and 20.00 processing fee and a 2.00 weighing fee. so for 100 pounds over the total fine would be $47.00. If it was a really good paying load then 47.00 ain't all that much.
I should clarify and state that the above statement would be true for vans operating in a NON CMV fashion.
If you were hauling a placarded amount of haz mat then they might try to ding you with points due to the new csa rules. And that in the long run will cost you more if you are in the habit of breaking rules and racking up points.
Jefferson3000
Expert Expediter
It's kind of like the guy running 2-3 sets of log books. It just ain't worth what you think you've gained.
nightcreacher
Veteran Expediter
there is also a miss use of equipment ticket that goes with the over weight