RE: Weight Distribution Hitch?

[Wayfarer]

 
Would someone explain for me the purpose of a weight distribution hitch (I guess that is what " WDH"  stands for?) and why I might need one.  So far, with my Coleman Utah and a basic Sway Bar I haven t had any problems with sway or handling.  I am thinking, however, of moving to a Hybrid such as the Kiwi or Starcraft in the 18  to 21  range and not more than 3,000 dry weight and reading the comments under the Hybrid forums it seems lots of folks are talking of getting/needing them.  What do they do?  Is one needed with a hybrid?  Cost?
 
 Appreciate any enlightenment on the subject.

[Miss-Teri]

 Wayfarer
We have absolutely no sway with ours (I assume the reason is the WDH), but one reason it was a must-have was to lift the back of our van off of the ground.  Without a WDH we wouldn t even be able to tow with all the weight on the tongue.  The weight distribution hitch distributes the weight so it s not localized in that one spot.

[mike4947]

 Wayfarer
A weight distribution hitch acts as a fulcrum and with the use of the spring bars transfers weight from the rear of the tow vehicle to the front of the tow vehicle.
 This of course alleviates the " droop"  TV s can get when the tongue weight is applied to the hitch and in the case where it would overload the rear suspension it transfer some of that weight to the front supension.
 Sway control is not a function of a WDH except in the case of the Reese mini WD350. Other WDH s can have sway control added in the form of a double cam addition or seperate friction sway controls.

[campingboaters]

 Wayfarer
A WDH connects the trailer with the tow vehicle and makes one continuous vehicle.  When you go over a bump, the entire setup goes up and down on the shocks of the TV instead of bouncing up and down at the hitch point.  A WDH levels the trailer with the TV and in doing so, transfers some of the trailer s tongue weight to the front wheels instead of only on the rear of the TV.  
 
 Sway control is something else.  That keeps the trailer from swaying side to side while traveling.  IF a trailer gets swaying side to side enough, it will start to take the TV with it which makes for a VERY dangerous situation.  Without a sway controller, when a tractor trailer passes you (and pushes your trailer and vehicle over from the wind it creates), it could send you into a tailspin.  Not to scare you or anything.
 
 We just upgraded to a hybrid last fall and we are SO glad we got the WDH.  It cost an extra $350, but we feel like our family s safety is worth a lot more than that.  The hybrid tows so much more smoothly than our pop-up did (without a WDH).  
 
 Some of the smaller pop-ups/ larger TV s may not need the WDH and other setups do.  If you start thinking you need to monkey with your rear suspension on your TV, you should first consider a WDH.  It makes a WORLD of difference for towing and saftey IMNSHO (in my not so humble opinion)!  []
 
 

[whitestar505]

 Wayfarer
Wayfarer,
 
    What I am going to tell you has been pass on to me by my dealer when I was going to buy a TT. My TV will tow around 6000 pounds and up to 750 lbs on the tongue. Thats Great but, not flat out. You guessed it, I need a WDH for the TV. Today the manufactures tell you the max you can tow, with or without additional equipment. Mostly with additional equipment. Soooo flat out I might be able to tow 3500 lbs at 350-400 lbs tongue weight. With the WDH a lot more. I understand that it also shifts the weight back and forth as it is riding to maintain a balance between the TV and the TT.
 
  Well, you got all I know.

[AustinBoston]

 Wayfarer
Note:  This is a bit long...
 
 Weight Distributing Hitches (aka Equalizing Hitches) distribute tongue weight from the rear axle to all three axles.
 
 Dead tongue weight (No WDH)
 
 Because the hitch ball is behind the rear axle, it acts as a lever.  Unlike a laod in the truck bed (centered over the axle), weight on the hitch ball actually applies more than the tongue weight to the rear axle.  So if your tongue weight is 400 lbs, the load on the rear axle may be as much as 500 lbs.  Since the total weight of the truck didn t increase, the extra hundred pounds had to come from somewhere.  It came from the front axle, with the weight there being reduced by 100 lbs.  The tongue weight is actually lifting the front axle!
 
 This leads to a number of problems.  First, the rear axle may now be overloaded (even though your tongue weight doesn t exceed the load weight you can put in  the bed of the pickup).  This can cause the rear end of the pickup to squat.  Second, because front axle weight is reduced, front end traction is reduced.  This is probably the worst thing that can happen.  At a time when you need more control because of the trailer, you have less.  Also because of the reduced front end weight, the front end may rise, exaggerating the " squatting"  of the truck.  Your headlights point at tree limbs instead of the road, and your puckup dosen t handle well.
 
 What the WDH does:
 
 A Weight distributing hitch " redistributes"  or " equalizes"  the weight on the tongue between the three axles.  In the situation described above, if a WDH were used and 250 lbs were distributed, then rather than having 500 lbs on the rear axle, there would be closer to 150 lbs.  The weight taken off is distributed to the other two axles.  The 100 lbs subtracted from the front axle would (mostly) be returned, and 125 lbs of tongue weight would be added.  In addition, 125 lbs would be forced back onto the trailer axle.  (The amount on the front axle and on the rear axle will be close to the same.  The exact amount depends on the ratio of the distances of each from the hitch ball.)  So now, instead of having 400 lbs on the hitch (and therefore 500 lbs on the rear axle), you have 400 lbs on the hitch, but it is broken up with 125 lbs one the front axle, 150 lbs on the rear axle, and 125 lbs on the trailer axle.
 
 How the WDH works:
 
 Imagine the handles of a wheelbarrow attached to the back of your pickup.  If you lift those handles, the back of the pickup rises and the front drops.  Weight is removed from the rear axle and added to the front axle.  At the same time, weight is being added to your feet.  Now imagine that instead of you holding up wheelbarrow handles, the trailer frame is holding up steel bars.
 
 This picture would be complete if we only drove on straight, level, smooth roads.  But I know I go over hills and bumps and around corners when towing.  In order to negotiate turns, the bars are mounted on swivels that allow them to swing side to side.  In order to deal with bumps and dips (and to maintain tension), the bars are made of spring steel and are designed to flex up-and-down.
 
 An artifact of the up-and-down flexing of the hitch and side-to-side turning is that the ends of the spring bars need to move back-and-forth.  Many WDH s deal with this movement by attaching the ends of the spring bars with chains.  Others take advantage of it for sway control purposes.
 
 WDH s and sway:
 
 A pure WDH has little impact on sway.  It helps some (but not much) by keeping the tow vehicle s front and rear suspension nearer the center of their normal travel, and they improve the front traction, but many drivers would not notice the difference.
 
 There are several enhancements to WDH s that can help to reduce sway.  A few small WDH s can be used with ordinary sway bars (and most larger ones can).  The Reese Mini-350 has the equivalent of a small sway bar built into it s mechanism.  Larger WDH s can be used with sway bars, but with larger trailers it s better to use dual-cam sway control.  Many have the dual-cam mechanism built in.
 
 I know there is a third (very expensive) approach that is far superior to both friction sway bars and dual-cam, but I can t picture it or remember what it is called.  It s high cost isn t justified for pop-ups.
 
 WDH s and tongue weight.
 
 It would seem that with the tongue weight redistributed, that the trailer now doesn t have enough tongue weight.  After all, we went from a 400 lb tongue to a 150 lb tongue, right?  Well, not quite.  The " 10-15%"  rule is an easily measured compromise.  What really counts is having 60-65% of the total trailer mass forward of the axle.  Since no one has found a reliable way of measuring that, it gets translated to 10%-15% of the trailer s weight on the tongue.  But when using a WDH, the center of mass hasn t moved, even though the weight has.  There is an adjustment, however.  For reasons I admit I don t understand, most WDH s recommend a tongue weight in the 12%-15% range, instead of 10%-15%.  So if your tongue is on the light side, you may need to shift weight forward when you go to a WDH.
 
 High forces.
 
 Because a WDH is trying to apply substantial forces to relatively distant points, the forces at the hitch itself can be huge.  Imagine trying to apply a force of 125 lbs on wheels that may be 15 feet away using a four inch lever!  Mechanical advantage works hard against hitch components.  For this reason, I avoid leaning, stepping over or straddling the WDH when it is hooked up or while connecting it.  Others have attached chains or cables to their spring bars so that they won t sail across the highway should something break.  I ve never heard of an accident from broken hitch components, but I m not taking chances.
 
 Austin

[Civil_War_Buff]

 Wayfarer
AB,
 
 What a great write-up....you sir are such an asset to this site and forum.  You are a literal camping encyclopedia!  
 
 Thanks so much!
 
 Larry

[AustinBoston]

 Civil_War_Buff

ORIGINAL:  Civil_War_Buff
 What a great write-up....you sir are such an asset to this site and forum.  You are a literal camping encyclopedia!  
 

 Naw, you can get anything from an encyclopedia.  I only answer the questions I want to answer (or the ones where I think I m an expert...).
 
 Austin
 

[Wayfarer]

 Wayfarer
I asked for enlightenment and that s what I got.  Thanks, Guys, for all your help.  Excellent treatise from Austin Boston!
 
 Wayfarer