Trailer swing while backing and position of tandems?

Because if it were to pivot at any other point it would require dragging the tires and the weight of the trailer across the ground and would require a lot more energy than simply rolling the tires. Plus it would require energy being applied at two points thus making it a much more complex process. If you took two bulldozers and pushed on opposite corners of the trailer and in opposite directions then it might result in a pivot point other than where the tires come in contact with the ground.

But that would not be a very efficient method of repositioning a trailer so instead of fighting the natural pivot point, you use it.

 

Good point.

Please respond to my post #40 on this thread. You could probably make some pithy remarks about that.

 

I’m kind of getting that feeling myself.

 

I have a hard time understanding why the trailer needs to have a pivot point at all.

 

Totally depends on the natural pivot point between the ice and the bottom of the trailer. Since we don’t know where this might occur, it would be harder to determine swing.

which is why having a pivot point of the tandems make backing and pulling out much easier because we know where the trailer will pivot.

 

The fact that you admit that you don't know where this "natural pivot point" would occur on a trailer without tandems shows that understanding this at the deep level that I am trying to understand it is not the most simple thing in the world.

 

https://www.amazon.com/General-Tool...ocphy=9012040&hvtargid=pla-613485899672&psc=1

Look at this protractor, but ignore the angle that it reads. Consider the bar as your trailer, and the point where the bar connects to the plate is your tandem position. The small end of the bar that reads the angle is your tail swing, the long end is being moved by the tractor. If you slide your tandems, it changes the length and alters the amount of tail swing you get.

If you really want to understand it, think of it as an advanced math problem combined with physics. The angle created between the truck and trailer dictates how the trailer is going to react. A 45 degree angle is going to create a balanced arc that will move forward(or backwards) and pivot equally. Anything between 45 and 90 degrees is going to pivot more than move. This is where the tail swing happens. At 90 degrees, the trailer will stop moving and will only pivot, which is how the protractor behaves when you spin it.

 

It doesn’t “need” one… if it’s sitting in place it doesn’t have or need a pivot point.

It’s only when one moves the trailer that physics comes into place and creates the natural pivot point. We use that naturally occurring pivot point to control the trailer movement and train new drivers what to expect when physics kick in.

 

LMFAO. I can guarantee you I understand this. I just set up a battery and an ink pen as a truck and trailer. Told my wife where the tandems were on the ink pen, and asked her what the tail would do when I drove the battery this direction. She said: "It will swing this way." And then gave me a look like why are you asking me such a stupid question.

Wrong. Dragging a trailer on ice with no tires just means the trailer will pivot at the first place that catches friction. It's the same thing as backing a spread axle without a dump valve. It's constantly changing which axle it pivots on base on terrain changes, and friction changes.

You're thinking this is all a "deep difficult concept", because you can't wrap your head around how obvious it is. And I know you aren't trolling, because I've seen other questions you ask. So if all of this is just a troll, then my hat is off to you for playing the long game.