Cat and weigh scale question

I get weighed every day or every other day ...
I set the parking brakes every time. I am on a scale with a ramp and a huge sign that says set your brakes.

Talking to the scale tech at that scale, he said it does not matter if the brakes are set or not when weighing the truck, the motion is what matters,

 

Air adds weight? What about snow, or if you have to pee... I don't know, I'm typically weighed when rolling, so maybe that would be most accurate by comparison, why did they set it up to make us stop for a cat scale?

 

Thank you...I'm not one to argue with these veteran drivers, but the whole thing sounds asinine to me...simple physics. It should not make any difference weather the truck is on, off, brakes set, or air bags full or empty. If the entire vehicle is positioned on the scale the way it's supposed to be...stopped on a scale or rolling like some DOT scales.

 

If I pull my yellow knob thing out, It only sets my drive brakes, my steer And trailer axles are free to roll, shouldn't be any binding going on.

 

Apparently you know the word physics but are not at all schooled in physics.

Raising or lowering ride height makes changes to weight on each corner of the vehicle. Even in F1 simulators I can see a difference in lap times with as little as a 2 millimeter change in front or rear ride height. When I raced RC cars I would see a difference in lap times with a millimeter of change. (not bragging that I was that good of a driver, but I was)

Just like moving tandems fore and aft to balance a trailer, dropping the air in the trailer suspension or tractor will change the balance and transfer weight.

Mikeeee

 

I understand the weight balance shift...it's a simple fulcrum effect. I was referring to the total gross weight of the vehicle being affected. I don't understand how a stationary object on a scale can become heavier or lighter based on the suspension or brakes...if I stood on my bathroom scale and lift 1 foot up with my weight balanced, the weight doesn't change. If I crouch down it stays the same also. I can't change the weight reading unless I shift some weight off the scale, or pull myself downward with the assistance of an outside object...how could a combination vehicle change it's total weight under those same circumstances???

 

You don't have steer brakes in your rig? What are you driving?

Mikeeee

 

Fulcrum is not the best analogy. Fulcrum uses a middle-ish grounded point in regards to leverage of weight on each end subject to length on each side from said point.

But yes. If you are not having an issue with tandem length and related drive/tandem weights then it does not matter what you do with your brakes when you only want a gross reading.

Mikeeee

 

I'm sorry, I'm better at describing a fat guy at a Buffett, but I'll try...
If I only pull the yellow knob out, only my drive axles are locked up, my steers and trailer axles are free, no brake pads against the drums.
But, I only pull my red knob when I'm parked for a while. Or switching trailers..