Weight distributing hitch

Submitted: Wednesday, May 25, 2005 at 10:41
ThreadID: 23287 Views:2144 Replies:6 FollowUps:3
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Does anyone know of a way of working out the weight transfer caused by the use of a weight distribution hitch? For example, say a trailer has an ATM of 1100kg including a ball weight of 100kg, how can you calculate the weight that is transferred to the towing vehicle's front wheels when a WDH is used?

I realise it will vary depending on the settings of the WDH, but is there a way of measuring the change in ball weight that results from different settings?
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Reply By: Wizard1 - Wednesday, May 25, 2005 at 11:54

Wednesday, May 25, 2005 at 11:54
I would contact Hayman Reese........

03 9702 9222 or

www.haymanreese.com.au
AnswerID: 112771

Reply By: Homebrewer - Wednesday, May 25, 2005 at 12:28

Wednesday, May 25, 2005 at 12:28
DerekH,
One way of working out what weight is transfered, is to use a weighbridge.Put the front wheels on the weighbridge take a reading, then engage weight distribution hitch, and take another reading. Do the same for the rear wheels,ei with and without hitch engaged, then put the trailer wheels on the weighbridge, and take another 2 readings. That will tell you how much weight has been transfered to the front wheels, how much to the trailer wheels and how fom the towball.This is best done with the trailer packed, as the ballweight may differ on an empty trailer.....I'm sure there is a more simple, so I await the responce of others.
The way I set my WDH, is to measure the distance from the front mudgard arch to the ground without the van on, and then, with the van on, adjust the hitch to bring front gard measurement back to where it was.
I hope this is of some help...Pete...
AnswerID: 112776

Reply By: Member - Ross P (NSW) - Wednesday, May 25, 2005 at 14:23

Wednesday, May 25, 2005 at 14:23
Now I could be wrong and if so I know you will be gentle if I am...

I think I have read some where that while you distribute the weight the actual weight on the ball doesn't change.

If I'm right maybe someone can give us a mathematical explanation.
AnswerID: 112810

Follow Up By: Member -Dodger - Wednesday, May 25, 2005 at 17:27

Wednesday, May 25, 2005 at 17:27
Correct,
All the weight distrubition hitch does is, distribute the weight to the front wheels using a fulcrum effect. The ball weight remains the same.
I used to have a handle on life, but it broke.

Cheers Dodg.

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FollowupID: 368994

Reply By: cmilton54 - Wednesday, May 25, 2005 at 19:57

Wednesday, May 25, 2005 at 19:57
Measure ball hight unhooked, hookup and tension hayman reese bars so ball hight is same as unhooked
AnswerID: 112869

Follow Up By: blackmax11 - Thursday, May 26, 2005 at 13:15

Thursday, May 26, 2005 at 13:15
Sounds sensible to me. Is it done with the vehicle loaded or empty?
Regards
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FollowupID: 369166

Reply By: cmilton54 - Friday, May 27, 2005 at 10:19

Friday, May 27, 2005 at 10:19
Blackmax11
Will not matter if loaded or empty as long as measurement is taken then done at same time.
AnswerID: 113158

Reply By: gottabjoaken - Friday, May 27, 2005 at 12:01

Friday, May 27, 2005 at 12:01
Technically you will find that the weight carried by the tow vehicle will be reduced, because the leverage effect will transfer some weight back to the trailer's wheels.

Put the tow vehicle only on the weighbridge.
Then attach the van and see the additional weight. = Static, level, stand-alone tow ball weight of the trailer
Then set up the WDH.
My guess is that the combined weight of the vehicle and static ball weight will drop a small amount.

But this is irrelevant. It does not permit you to exceed the declared capacity limit of the vehicle.

When the manufacturer states a figure as permitted, this is the static, stand-alone ball weight of the trailer. This figure has been chosen with the knowledge that the actual weight being carried by the vehicle is dynamic during towing. And even when they specify use of a WDH, then still the static, stand-alone ball weight of the trailer is what they will consider in declaring the limit.

They have also probably considered a specific tow bar design and distance of the ball from the rear axle, so any extended tongue would also impact the carrying capacity of the vehicle.

Suspension movements, angles from the horizontal, accelleration and braking all constantly vary the actual weight being borne by the towball.

So best to know that you are inside the limit quoted, and not be too keen to be "on the line". I can't see why so much effort seems to be taken to stretch the simple rules and find justifications for it.

What we have to do is work on the manufacturers to do either what Nissan do and declare a table of tow ball weights according to what other load is in the vehicle, or to declare a tow ball weight factor that must be used to include the tow ball weight in the total load calculation.

Either way, getting manufacturers to change is only likely to happen by having the grounds to sue them!!!!!

my tuppence worth!

Ken
AnswerID: 113167

Follow Up By: pjchris - Friday, May 27, 2005 at 16:26

Friday, May 27, 2005 at 16:26
In the Mitsubish Pajero manual there is agraph of ball weight versus vehicle payload that clearly shows how the vehicle payload decreases as the weight on the ball increases.

This graph has two different lines, one where the allowed actual payload is equal to the maximum vehicle payload minus the weight on the ball and another which is used when you have a weight distributing hitch. this secon one is lower and the actual allowed vehicle payload is the maximum vehicle payload minus half the ball weight (Might be 2/3, I will read it tonight).

So using a weight distributing hitch allows higher vehicle payloads for a given ball weight than without the hitch.

Hope that's clear...

Peter
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FollowupID: 369350

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