Does overly biased tandem weight add drag?

It matters not.

Gross weight versus a mountain, you have 4 forces. Horsepower, torque for forward versus total vehicle weight modified by wind conditions, traction problems if any and the specifications of the tractor. There are thousands of combinations of ratios etc. (God help us all when they begin to make variable infinite transmissions big enough to take class 8 duties...)

And there is the drag that is created by the passage of the vehicle through the earth's atmosphere, severity of the upgrade and the tires contact with the pavement and so on.

It does not matter where you put the weight.

I say this...

I absolutely hated the 20 foot seacan with 60K in the box. The #### thing will lay down on a simple 35 mph curve if you let it.

The Ravens would allow 40000 pounds on the back spread axles. It still meets bridge law. It ran the same as it would at 34 and 34 etc on tandems. In fact if you piled too much on the tractor drives more than what they are built for total weight at the factory then you will hurt the tractor.

Anything else is down to behavior on the road which varies in small ways not worth mentioning here.

 

I agree with him. I prefer the drives to be heavier than the trailer. Not because of fuel savings, but because of handling issues. It may not mean much on dry road, but on wet and slick roads, you don’t want the tail wagging the dog. And traction is much better when you have weight on your drives.

 

I'm no expert but I would think having more weight on the drives on slick conditions would allow less slippage when using the jakes. That's my guess again I'm no expert.

 

I think with a closed tandem trailer more weight on the drives feels like the truck pulls better, don't know about fuel mileage. I will say with my spread I prefer it to be 2-3K heaver than the tandems (great ride) but I do feel as though the truck won't pull as strong. I used to pull a lot of local van loads of stamped steel in baskets and they'd always be loaded a little different every time, I always knew when to much weight was back of the trailer truck did not pull as strong. So I tend to agree it does effect how the truck pulls. I honestly never gave a thought to fuel mileage.

 

Well the analogy you wrote had some flaws. You said something about the dad pulling the kids wagon. Thing is if dad was heavier he probably got stronger from holding his weight but the lighter person pulling heavier kids is weaker. In the case of the truck power is the same regardless because an engine can only put out a certain amount of force.

Fuel pushes the pistons which turn the crank goes to the tranny then diff, amount of fuel used depends on the amount of force needed to pull. Amount of force needed depends on weight, resistance, velocity, and traction. I think the only thing that being heavier on one side does is affect stability.

 

The physics its sound. Basically its easier to carry weight than it is to pull it. Just don't take it to extremes and load the truck axles to max while the trailer axles have very little load on them.

 

But if a truck puts that much torque out, is it loosing efficiency when the suspension expands due to light weight on drives compared to what it's pulling? Is that energy expanding into the suspension and not the driveline? IDK if that makes any sense, it kinda does in my head.