While Weight Distributing Hitches are widely used/recommended and serve at the useful purpose of assisting the tow-vehicle maintain somewhat-equal weights on it’s own axles on Level Ground….I don’t like them….and I don’t use them.
Here’s why:
Under ordinary, non-towing conditions, the tow-vehicle are not expected to carry equal weights among all axles. The truck, in its design, its anticipated that weights are not equally shared by the axles…. Nothing New here.
A WDH “stiffens” the axle-combination across all axles, two-vehicle And trailer.
At first this appears desireable. It works to prevent an unloaded steering-axle (loss of steering authority) and it prevents overload of rear axle (due to undesirable excess tongue-weight). It also helps counter headlamp-beams from blinding oncoming drivers….due to excess cargo and/or tongue wt.
It does this by re-distributing the load using a system of spirngs and shackles to impart a “twist”…. transferring loads and strain upon the tow-vehicle hitch and frame.
The result is a more-level tow-vehicle throughout the trip.
The thing I hate about it is: The ride, and the torture it placed upon the tow vehicle. This is not a problem for vehicles designed for it. I’m not convinced they are so-designed.
The truck has it’s tow-limitations specified.
1-There’s a stated maximum towing capacity: This is the amount of total or gross weight of the trailer.
That should never be exceeded for tow-vehicle structural and braking limitations.
2-There’s a stated maximum tongue-weight: This is the amount of weight for which the tow vehicles structure and frame is designed.
Trailers should also be largely self-supporting, I.E., they should be within their own limitations of cargo and gross weight … and they should have that weight so-distributed upon the trailer to “balance” properly…with the result that 10-15% of that weight should rest upon the hitch. This helps prevent “sway” and assures that the tongue weight is well placed upon the tow-vehicle’s hitch-point for tow-vehicle control of the trailer.
The WDH can mask excess tongue weight and it’s unfortunate, but most users are not conflicted by this improper trailer loading when a WDH levels out the combination.
WDH’s are commonly used to “mask” an improper tow-vehicle-and-trailer weight-combination. However, even if that is carefully considered and is not allowed to occur, it is troublesome.
The most egregious problem I personally have with WDH’s are that they “make rigid” the combination and prevent “fliex” between the Toe-Vehicle (TV) and trailer.
Imagine this:
You are driving thru or across a “swale”…. a low-area. If you are using a WDH…. the TV frame is made-rigid with the trailer … and the TV steer-axle is momentarily made “light” …and then the rear axle made-light (reducing traction) ….and the TV Frame is highly-stressed throughout.
Imagine also that you are approaching a raised Rail-Road crossing:
As the TV approaches the embankment, the steer axle becomes more-heavily-loaded while the rear/traction axle is Un-loaded…and the Combined Gross Wt is transferred thru the frames to the TV steer axle and the trailer axles…. and does this by stressing the TV Frame via the WDH.
Would we accept a trailer that stiffens our combination laterally?… where the hitch used a transfer-mechanism to pre-load the TV frame in a plan to prevent or resist turning left/right ?
That is what the WDH does longitudinally. It prevents the combo from being able to “flex” vertically. (This is why a WDH seems to make the ride in the TV harsher.)
So a WDH has the effect of constantly varying the load and the authority of the steer and the traction axles of the TV. And it does that by using the Frame and Hitch of the TV to force the combo to behave as One-Long-Assembly.
My usual “tow” is a 5K lb Airstream. When we participated in the Airstream Club activities, it was a common recommendation from others that we get/use a WDH.
In actual fact, one of our closer club-friends actually GAVE us one.
It sits on the concrete floor in the corner of the hangar.
I’ve come to believe, that in some cases, trailer salesmen upsell customers on WDH with the full knowledge that users commonly exceed the towing-capacity of their TV’s using the larger trailer they’re selling.
Even if that is not the case, it’s an additional sales-item they push, …when in fact the customer is encouraged to believe they are increasing some “safety margin”…. Not True if one realizes that WDH will frequently reduce steering authority and reduce TV traction on uneven roadways. (while decreasing ride-comfort and increasing vehicle structural-strain.)
The answer (in my opinion) is to adhere to tow-capacities and hitch/tongue weight limits using an ordinary ball hitch.
If the trailer places the tow vehicle in an unacceptable attitude when connected…. and you want to tow that thing anyway…. Reduce the cargo wt. ..and/or… get a larger, more-capable tow-vehicle.
IMO
