Hensley Arrow: How does it REALLY work?
There have been several discussions on this hitch that have become somewhat 'controversial'. I am NOT trying to stir this controversy/bashing back up. Instead, I'd like to see a good, intelligent di...
Forum Discussion
Hensley's new 2005 patent hitch drawings
The new Hensley hitch Patent #6,851,696
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Briefly stated, the invention is a hitch assembly comprising a hitch bar assembly coupled with a hitch receiver of a tow vehicle for transferring pulling and stopping forces to and from the tow vehicle. A hitch box assembly couples with the hitch bar assembly for transferring pulling and stopping forces to and from the hitch bar assembly, the hitch box assembly having a first pivot point. An overcenter latch assembly secures the hitch box assembly to the hitch bar assembly. A front support member pivotally connects to the hitch box assembly at the first pivot point for transferring pulling and stopping forces to and from the hitch box assembly and for pivoting during turns. A strut assembly pivotally connects to the front support member for transferring pulling and stopping forces to and from the front support member wherein the strut assembly can pivot vertically for accommodating uneven roads during driving. Also, the strut assembly includes a second pivot point. A ball mount assembly pivotally connects to the strut assembly at the second pivot point for transferring pulling and stopping forces to and from the strut assembly. The ball mount assembly laterally pivots about the second pivot point within the strut assembly during turns. The ball mount assembly includes a tail tube extending rearwardly. A ball plate assembly attaches to the ball mount assembly for transferring pulling and stopping forces to and from the ball mount assembly. The ball plate assembly includes a hitch ball for removable attachment of the trailer for transferring pulling and stopping forces to and from the trailer. A tail support assembly attaches to a trailer frame and couples with the tail tube whereby the tail support assembly restricts lateral movement of the tail tube and the ball mount assembly so the trailer remains relative to the ball mount assembly at all times. A slide assembly resides within the ball mount assembly such that forces inherent in towing the trailer are not transferred through the slide assembly. The slide assembly slides forwards and backwards to accommodate the change in radial movement of the converging links during turns. Converging links pivotally connect between the hitch box assembly at the first pivot point and the slide assembly whereby the angular position between the first pivot point and slide assembly can be varied. The converging links effectively move the pivot point between the tow vehicle and trailer forward of the hitch assembly. In addition, forces inherent in towing the trailer are not transferred through the converging links. A hanging support assembly attaches to the strut assembly including vertical links pivotally attached to the ball mount assembly for transferring tongue weight from the ball mount assembly through the strut assembly and front support member to the hitch box assembly and hitch bar assembly so tongue weight is not exerted on the converging links or the slide assembly. A jack assembly attaches between the trailer frame and the front support member for distributing tongue weight among tow vehicle wheels and trailer wheels.
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The original hitch Patent #4,722,542
--quote--
Fishtail sway is caused by the large distance between the rear axle of the tow vehicle and the hitch assembly and is aggravated by lateral forces against the vehicle caused by winds or passing vehicles. Previous attempts to solve fishtail sway involve stiffening the connection between tow vehicle and trailer by using various methods of friction. While these methods help some, none completely correct the problem.
Fortunately, in U.S. Pat. No. 4,722,542, hereafter referred to as the "Hensley hitch", the sway problem is effectively corrected by forcing the hitch to turn through converging links that effectively move the pivot point between the tow vehicle and trailer to a point near the rear axle of the tow vehicle. Therefore, this design provides better steering and control of the trailer by eliminating trailer sway. While the converging links do this very well, the gross trailer weight is limited by the size and design of the converging links in '542 because so much of the tongue weight is supported by the converging links. As a result, increasingly heavier tongue weights require larger links, larger bearings, larger spindles, and larger related support systems. Increasing the size of these parts also increases both the hitch weight and the cost of manufacturing. In addition, the Hensley hitch needs workable brakes on the trailer controlled from the tow vehicle. Without trailer brakes or even with surge brakes the converging links tend to move to one side or the other due to the trailer pushing on the hitch assembly when the tow vehicle brakes are applied.
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The new Hensley hitch Patent #6,851,696
--quote--
Briefly stated, the invention is a hitch assembly comprising a hitch bar assembly coupled with a hitch receiver of a tow vehicle for transferring pulling and stopping forces to and from the tow vehicle. A hitch box assembly couples with the hitch bar assembly for transferring pulling and stopping forces to and from the hitch bar assembly, the hitch box assembly having a first pivot point. An overcenter latch assembly secures the hitch box assembly to the hitch bar assembly. A front support member pivotally connects to the hitch box assembly at the first pivot point for transferring pulling and stopping forces to and from the hitch box assembly and for pivoting during turns. A strut assembly pivotally connects to the front support member for transferring pulling and stopping forces to and from the front support member wherein the strut assembly can pivot vertically for accommodating uneven roads during driving. Also, the strut assembly includes a second pivot point. A ball mount assembly pivotally connects to the strut assembly at the second pivot point for transferring pulling and stopping forces to and from the strut assembly. The ball mount assembly laterally pivots about the second pivot point within the strut assembly during turns. The ball mount assembly includes a tail tube extending rearwardly. A ball plate assembly attaches to the ball mount assembly for transferring pulling and stopping forces to and from the ball mount assembly. The ball plate assembly includes a hitch ball for removable attachment of the trailer for transferring pulling and stopping forces to and from the trailer. A tail support assembly attaches to a trailer frame and couples with the tail tube whereby the tail support assembly restricts lateral movement of the tail tube and the ball mount assembly so the trailer remains relative to the ball mount assembly at all times. A slide assembly resides within the ball mount assembly such that forces inherent in towing the trailer are not transferred through the slide assembly. The slide assembly slides forwards and backwards to accommodate the change in radial movement of the converging links during turns. Converging links pivotally connect between the hitch box assembly at the first pivot point and the slide assembly whereby the angular position between the first pivot point and slide assembly can be varied. The converging links effectively move the pivot point between the tow vehicle and trailer forward of the hitch assembly. In addition, forces inherent in towing the trailer are not transferred through the converging links. A hanging support assembly attaches to the strut assembly including vertical links pivotally attached to the ball mount assembly for transferring tongue weight from the ball mount assembly through the strut assembly and front support member to the hitch box assembly and hitch bar assembly so tongue weight is not exerted on the converging links or the slide assembly. A jack assembly attaches between the trailer frame and the front support member for distributing tongue weight among tow vehicle wheels and trailer wheels.
--end quote--
The original hitch Patent #4,722,542
--quote--
Fishtail sway is caused by the large distance between the rear axle of the tow vehicle and the hitch assembly and is aggravated by lateral forces against the vehicle caused by winds or passing vehicles. Previous attempts to solve fishtail sway involve stiffening the connection between tow vehicle and trailer by using various methods of friction. While these methods help some, none completely correct the problem.
Fortunately, in U.S. Pat. No. 4,722,542, hereafter referred to as the "Hensley hitch", the sway problem is effectively corrected by forcing the hitch to turn through converging links that effectively move the pivot point between the tow vehicle and trailer to a point near the rear axle of the tow vehicle. Therefore, this design provides better steering and control of the trailer by eliminating trailer sway. While the converging links do this very well, the gross trailer weight is limited by the size and design of the converging links in '542 because so much of the tongue weight is supported by the converging links. As a result, increasingly heavier tongue weights require larger links, larger bearings, larger spindles, and larger related support systems. Increasing the size of these parts also increases both the hitch weight and the cost of manufacturing. In addition, the Hensley hitch needs workable brakes on the trailer controlled from the tow vehicle. Without trailer brakes or even with surge brakes the converging links tend to move to one side or the other due to the trailer pushing on the hitch assembly when the tow vehicle brakes are applied.
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