towbars and load levelers

[nabstud]

Sam, I understand the concept and understand how throwing the weight to the front is benaficial, what I fail to see is how, given the point where the weight is transfered from the trailer to the tow vehecle, how it can throw the weight, and further, if the trailer is properly loader how there would be enough weight to make any significant difference should some of that weight be transfered to the steer.

The down weight on the ball is pushing down on the rear of the car, rotating the front of the car up - with the "axis of rotation" being the rear wheels.

A weight distributing hitch (what we called "torsion bars" when I was a kid) applies torque to the hitch, effectively rotating the front of the car down - with the "axis of rotation" being somewhere around the towball.

Alternative way to look at it?
Imagine a horizontal line through the trailer's A-frame, extending from the car's rear wheels through to the trailer's wheels. The trailer's ball weight is trying to bend that line down. A weight distributing hitch is trying to bend it in the opposite direction.

like I stated in my first post I havn't seen one, so I am not entirely sure as to what they look like and where the points of contact etc are, but from what I gather this is all at the hitch, which is all behind the rear \ drive axle.

SO

the imginary line explination i get, didn't need that, but it is a good way to explain it so will run with that to try and explain where I have a problem.

so we are all in agreeance that a properly loaded trailer will have X% of the GVM of the trailer or x kilos to a certain max dependant on the vehicle and hitch and allowable towball \ hitch weight forward of the point of ballance.

we can also agree that the tow point is behind the rear axle of the tow vehicle, and when you put weight behind this axis point you will take weight off the front of the vehicle.

we can also agree that this is undesirable, and the best option is to try and share or distribute the weight evenly over the entire vehicle, I think we all know why.

Enter the Load Leveler

So again, I understand why you would want to throw the weight evenly over the tow vehicle, but unless the point of contact of the weight is past the axis, how does it do what we are wanting it to do?

So, given:

-the towball weight pushes the rear of the car down
-the front wheels lift up due to the rear axle being the point of axis,

how does installing a load leveller from the towball, which is further back than the axis point, to the drawbar apply (rotate/redistribute) weight to the front wheels?

EDIT: is the axis of rotation the towball or rear axle?

[BOGAN V8]

You can never tow over the amount the car is rated at. Regardless of what ever you thing is "right" or "safe" or what some bloke in a caravan park told you.

You obviously don't get it.

well that statement is clearly wrong.
of course you can tow over the amount the car is rated at, it happens everyday, hell, just about everytime a 4by gets towed on a car trailer.
consider that your average Landy/patrol will weigh between 2500 and 3000kg and your average car trailer will weigh 600 to 900kg. thats a possible agg weight of 3900kg and no 4by on the market (- F250) can legally tow that weight.
even at 3100kg there are few 4by's that can legally tow that weight.


Saying "You can never tow over the amount the car is rated at" is like saying " You can never remove swaybars and fit beadlocks to a 4x4"

The differance between you and the bloke in the caravan park "giving advice" is that he's not a salesman and he'll tell you what works for him, he's got no reason to lie.

You obviously dont get how wrong you are bout the weights.. apart from the legal side of it.. What bout insurance side of it and the fact that you might kill someone because you could stop your camry towing 3 tonne.. They put towing limits on vehicle for a reason because the car body/chassis can not SAFELY tow anymore than that.... I prey to god that i am never in front of you when your towing.

As you said the guy in the caravan park knows what works for HIM!!! not what works for everyone else and half of them dont know the full legal side of what they are towing

I have seen Camrys, Commodores, Falcons with cracks in the rear end becasue the owners have been towing more than what is allowed for that towbar (1250kg, 1600kg, 2300kg) They all blolt up with different bracing to pull on more parts of the vehicle

Below is a link for people to have a look at as to what one looks like



EDIT by Strange Rover...got rid of the long link

Not saying they are must but they do help with the towing of a (DRAWBAR HEAVY) van trailer or whatever it may be.....

[-Scott-]

An amateur attempt at explaining how these things work. It's simplistic, and probably full of holes.



The thick black bit is a representation of what we called (when I was a kid) the "torsion bar". In reality, the vertical bit is attached to the towbar such that lifting the horizontal part of the torsion bar imparts a torque (rotation) on the towbar.

The chain (red) connects the torsion bar to the a-frame of the trailer, and is under tension. Because the torsion bar is attached to the car, the tension in the chain is pulling the torsion bar up to the trailer (the thick blue arrow), and pulling the trailer down to the torsion bar (the thick green arrow). Let's look at each force separately.

The thick green arrow is producing a torque around the green cross (in the tow ball) which is represented by the green curve. This torque, operating around the same (green) axis, is effectively adding down force over the axle of the trailer. We'll come back to that.

The thick blue arrow is producing torque around the blue cross (hidden where the torsion bar crosses the "tow bar"). This torque, operating around the blue axis, is effectively adding down force over both of the car's axles, but I've only drawn an arrow over the front wheel to minimise confusion.

So, the two torques are adding downforce over the car's front axle, and over the trailer's axle. But the total downforce of the car and trailer combination can only come from the combined weight.

So, if there is (effectively) extra weight over the trailer's axle, but the trailer still weighs the same, there must be less weight on the towball.

If there is (effectively) extra weight over the car's front axle, and less weight over the towball, there must be less weight over the car's rear axle.

So - what did I get wrong?

[Strange Rover]

Enter the Load Leveler

So again, I understand why you would want to throw the weight evenly over the tow vehicle, but unless the point of contact of the weight is past the axis, how does it do what we are wanting it to do?

Its not an easy concept to explain...I think Scott is doing a very good job.

But I can assure you that without a load distribution hitch you can attach a trailer with, say 250kg, ball weight and it will compress the rear suspension by say 2inches and lift the front suspension by say 4 inches....a really bad setup that will handle like crap.

Now if you add a load distribution hitch and really crank it up it will lift the rear of the tow rig up and it will compress the front...you can easily set it up so that even with 250kg ball weight the front suspension compresses and the rear compresses also...the arms in the distribution hitch lever on the rear of the tow rig to put weight n the front suspension.

In effect it even workes better cause when you jump on the brakes ordinarily the trailer brakes will ceate even more ball weight as the trailer tries to rotate forward and tries to lift the front wheels off the ground...with the load hitch when you hit the brakes it will plant the front tyres harder. Same thing when you drive fast through a dip.

With a load distribution hitch it is theoretically possible, if you cranked the arms up hard enough, to completely lift the rear tyres off the ground and only have the whole thing sitting on the front tyres and trailer tyres only...if you can get your head around this concept you should be able to understand how it puts weight forward.

Sam

[CWBYUP]

You obviously dont get how wrong you are bout the weights..

Dont worry Bogan he's from WA. As long as he stays there it won't be our friends or family he kills one day.

Scott

The drawing you have done is what I call a torrsion bar or medium duty weight distribution hitch. Usally used for ball weight of between 82kgs and 130kgs.

The photo Bogan V8 posted is what I call the call the heavy duty one. Ball weights of 100ks up to 280kgs.

You have explained it very well.

I any one is SERIOUSLY interested in using weight distrubution systems I have some Hayman Reese DVD's at work that explain and shows how it all works. I can send it to some one if they could upload it to you tube etc.

Nick

[frp88]

I have the Mini hitch on my 18 foot van and it make a HUGE diffrence to my middie. I think the diffrence is even more due to the wheel base been shorter the normal.

[Tiny]

so it is not really distributing weight to the front or forward of the rear wheels \ axis but rather re distributing the towball weight back to the trailer rather than applying excess weight over the towball. Its safe to say that 200kg over the tow point = far more effective weight due to the lever action and the load leveler allows you to have adequate weight to the front of the trailer for control without that weight being transfered to the tow vehicle with the result of a far better handling combination overall

more simply, less weight over the tow point means less levering action on the tow vehicles meaning the same effective weight is maintained over the steer as it would with no load at all

[Tiny]

With a load distribution hitch it is theoretically possible, if you cranked the arms up hard enough, to completely lift the rear tyres off the ground and only have the whole thing sitting on the front tyres and trailer tyres only...if you can get your head around this concept you should be able to understand how it puts weight forward.

Sam

this would be counterproductive methinks

intereresting thought, someone who did not know how to set one up properly could actually create more problems than the exxcess weight over the tow point would have casued in the first place.

[-Scott-]

Bogan, could you help us out and edit that long link out of your post? Forever scrolling the page sideways is making this thread difficult to follow - well, for me, anyway.

I presume the following pic is the one you were after?


If so, please replace the link in your previous post with the following text:

Code: Select all

[img]http://www.haymanreese.com.au/consumer/products/wdh/wdh.jpg[/img]

Thanks.

[Strange Rover]

so it is not really distributing weight to the front or forward of the rear wheels \ axis but rather re distributing the towball weight back to the trailer rather than applying excess weight over the towball. Its safe to say that 200kg over the tow point = far more effective weight due to the lever action and the load leveler allows you to have adequate weight to the front of the trailer for control without that weight being transfered to the tow vehicle with the result of a far better handling combination overall

more simply, less weight over the tow point means less levering action on the tow vehicles meaning the same effective weight is maintained over the steer as it would with no load at all

I guess it does take weight off the rear tyres and redistributes it onto the front tyres as well as the trailer tyres. End result is the front tyres of the tow rig get planted onto the ground which makes everything so much better.

Sam

[BOGAN V8]

Bogan, could you help us out and edit that long link out of your post? Forever scrolling the page sideways is making this thread difficult to follow - well, for me, anyway.

I presume the following pic is the one you were after?


If so, please replace the link in your previous post with the following text:

Code: Select all

[img]http://www.haymanreese.com.au/consumer/products/wdh/wdh.jpg[/img]

Thanks.

I edited it without clicking a button thanks Sam

[chimpboy]

Do I have this right?

The load leveller acts like a tension spring that tries to make the whole car-trailer system "arch its back" with the towball rising up?

like this exaggerated diagram I made suggests:



Is that right?

I spent a while thinking about them when they were first mentioned and I couldn't really get my head around how they'd work but if I've understood Sam and Scott's descriptions then they are quite clever and I can see how they would help in controlling a heavy trailer. What I couldn't work out was how they moved weight to the front wheels but I can see how now.

How do you crank them up though?

[steel]

Not saying they are must but they do help with the towing of a (DRAWBAR HEAVY) van trailer or whatever it may be.....

LOL after all that you ended up agreeing with me!! LOL

[BOGAN V8]

Do I have this right?

The load leveller acts like a tension spring that tries to make the whole car-trailer system "arch its back" with the towball rising up?

like this exaggerated diagram I made suggests:



Is that right?

I spent a while thinking about them when they were first mentioned and I couldn't really get my head around how they'd work but if I've understood Sam and Scott's descriptions then they are quite clever and I can see how they would help in controlling a heavy trailer. What I couldn't work out was how they moved weight to the front wheels but I can see how now.

How do you crank them up though?

You can adjust them by the head angle and the amount of links used on the chains to give you more torsional force

[BOGAN V8]

Not saying they are must but they do help with the towing of a (DRAWBAR HEAVY) van trailer or whatever it may be.....

LOL after all that you ended up agreeing with me!! LOL

Yeah i did agree on the heavy drawbar opinion as who knows what the Op's drawbar will be, could have tool box full of spares or whatever on it so a WDH would help him out....

[Strange Rover]

Do I have this right?

The load leveller acts like a tension spring that tries to make the whole car-trailer system "arch its back" with the towball rising up?

like this exaggerated diagram I made suggests:



Is that right?

I spent a while thinking about them when they were first mentioned and I couldn't really get my head around how they'd work but if I've understood Sam and Scott's descriptions then they are quite clever and I can see how they would help in controlling a heavy trailer. What I couldn't work out was how they moved weight to the front wheels but I can see how now.

How do you crank them up though?

Yep - thats right.

How to crank them up...you see in the picture how the chain attaches the ends of the bars to the A frame...well the tighter (or shorter) you make the chains the harder the arms lift up (and try to rotate the tow bar) and therefore the more weight the setup takes off the rear tyres. To adjust the chains you rotate the lever thingee down...hook the chain onto whatever link and use a piece of pipe to rotate the lever thingee back up and put the locking clips in.

The arms of hayman reese distribution hitch come in three different stiffnesses (they are made out of spring steel) which are designed for different maximum ball weights...from memory they are 550lb, 750lb and 1000lb ( so 250kg,350kg and 450kg ball weight).

They really are good bits of gear and work incredibly well.

Sam

[KiwiBacon]

Just to throw in an extra complication.

Here in NZ, load distributing hitches are very rare (I've never seen one). Yet the ford rangers here are rated to tow 3,000kg on a braked trailer with a genuine ford towbar.
http://www.ford.co.nz/servlet/ContentSe ... &c=DFYPage

Territory 2300kg, both the 1600kg and 2300kg ratings are for the HD kit including the load leveller (which I've never seen used).
http://www.ford.co.nz/servlet/ContentSe ... &c=DFYPage

[tweak'e]

Just to throw in an extra complication.

Here in NZ, load distributing hitches are very rare (I've never seen one). Yet the ford rangers here are rated to tow 3,000kg on a braked trailer with a genuine ford towbar...........

yeah i've never seen one. i think thats partly due to people being cheap.
2500kg trailer is common size and only has to have override brakes. i don't see many electric brakes here.
i usupect a lot do not have brakes at all !

however stupid thing here is thats its legal to tow 3 ton with a 500kg towbar. the only real requirement is that you can stop withen a certain distance.

however big thing here is most people do not drive vary far.

[KiwiBacon]

however stupid thing here is thats its legal to tow 3 ton with a 500kg towbar. the only real requirement is that you can stop withen a certain distance.

There are no legal requirements for a private passenger vehicle towbar other than looking safe enough to pass a WOF.
It's got to be a commercial vehicle or heavy vehicle before RTCE (road transport certifying engineer) certifications are required. Just listen to the whining of people who need to get theirs certified.

Of course, you're never immune from prosecution if your dumbness causes loss or injury to other people.