Moving sliding 5th wheel
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Inkeper
Well-Known Member
It took 100 pounds off the trailer. Adding fuel puts weight on both my steers and drives pretty much equal.
Tim
U.S.Constitution
And how far forward did you move it to get 1200 pounds?
Duck
Sarcastic remark goes here
There's no way that sliding your 5th wheel can possibly affect your trailer axle weights. That 100 lbs is a scale variance.
At free scales like at shippers, and a couple times when I had an oddly loaded trailer & had to reweigh at a Cat scale, I've seen my gross weight change by up to 100 lbs, which I know is impossible if not for a scale error.
Rigjockey
In Gord we trust!
Why would it not. If you shifted weight forward it has to come from somewhere. The weight from the trailer would be minimal, It still exists.
Duck
Sarcastic remark goes here
You're not sliding the king pin on the trailer. You're just changing where it rests on the truck. Therefore the fore/aft position of the 5th wheel doesn't have any effect on the trailer axle weights.
When you move the 5th wheel forward, weight is transferred from the drive axles to the steers.
Rigjockey
In Gord we trust!
I beg to differ. When you slide the fifth wheel, It in fact changes the position of the kingpin. over the drives.
Duck
Sarcastic remark goes here
The king pin doesn't move like the tandems do. It's welded in one place.
When the 5th wheel moves, the king pin doesn't move, relative to the trailer. The king pin would have to move relative to the loaded trailer in order to have any effect on the trailer axle weights.
The 5th wheel pivots on it's own little axis, ya' know how it tips back when you're un-hooked? It pivots so you can start the tractor up a sharp incline without breaking the king pin off. With the 5th wheel locked around the king pin, the weight of the front half of the trailer is applied to the tractor at that pivot point. And because it pivots, all that can happen when you move the thing forward is weight will be transferred to the steers. It's physically impossible for the trailer axle weights to change even the weight of a feather.
I think you're just having a hard time understanding the explanation from reading words on a screen. I'm the same way most of the time. I need to see diagrams or animations before it "clicks" in my head if I can't see something in real life.
Rigjockey
In Gord we trust!
I still beg to differ. The teeter totter effect. If the weight is pushed forward it has to take weight off from the aft.It has to
Rigjockey
In Gord we trust!
Really Scooterdude. Sliding the fifth wheel does not change the position over the drives. Has the kingpin not been moved forward at all over the drives.
Duck
Sarcastic remark goes here
Yeah you're gonna need an animation or something. If you were right here in front of me I'd take some scraps of wood & some bricks & a bathroom scale or something for a little physics demonstration.
Think about this though. On the rear of the trailer, the load is supported by the tandems that slide relative to the trailer. But on the front, the load is supported by a stationary king pin. Even though the 5th wheel moves, the part of the trailer that holds the weight doesn't move relative to the trailer. It only moves relative to the tractor's axles. So it moves weight between the tractor's axles.
Yes the king pin moves relative to the tractor's axles, but it's not moving the king pin relative to the trailer, which would be the only way to affect the trailer's axle weights without sliding the tandems.Really Scooterdude. Sliding the fifth wheel does not change the position over the drives. Has the kingpin not been moved forward at all over the drives.
Rigjockey
In Gord we trust!
I never said it moves the kingpin relative to the trailer. It moves it over the drives. Add weight to the steers and drives, It has to come from some where. Are you saying that if you shift 200 lbs over the drives, The tandems weight on the trailer will still stay the same.
Duck
Sarcastic remark goes here
If it puts 200 lbs on the steers, it takes 200 lbs off the drives. The only way to add weight to BOTH the steers & drives (without adding fuel or freight) is to move the trailer tandems back but we're not talking about moving the trailer axles, just the 5th wheel.
Yes.
Rigjockey
In Gord we trust!
Excellent comment! Thank you for your participation, Very informative. Scooter.
Duck
Sarcastic remark goes here
I don't have any tattoos.
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