Re: [a/s] Hitch adjustment

[Perry Scudder <perryjoe@xxxxxxxxxxxxx>]

Hi folks,
Sense it is Saturday morning and I have time, I am going to do something I don't
normally do. I am going to put in a plug for a product I am really impressed
with - The Hensley Arrow Hitch.

There are three pieces of data that can help lend some credence to what I am
about to try to do. First I have a degree in Technical Engineering, second I
have been towing 20' to 30' travel trailers and boats for 25 years, and third I
just put the first 1000 miles on a 34' Airstream hooked to a 2000 GMC 2500
pickup rated to tow 11,200 pounds with a Hensley Arrow.

If one takes a look at a trailer and tow vehicle moving down the highway, it is
a series of rigid members, pivot points with a hinge in the middle someplace.
The rigid members are the trailer and the tow vehicle. They both have a pivot
point established by their non steerable wheels, this pivot point will cause a
force applied no one side of the pivot to cause the other side of the pivot to
move in the opposite direction. In other words, if you push to the right on the
left rear corner of the trailer the left front corner will move to the left. The
same is true for the two vehicle. We live with these forces every day where we
are towing or not. The forces on the tow vehicle take place all the time, but we
unconsciously correct for them by turning the steering wheel to keep us going
where we want to go.

Picture towing with a conventional hitch and being passed from the rear by a
large object with a huge "bow wake" of air rushing out to the sides. This "bow
wake is just like that of a boat as it moves through the water, and is a BIG
force. This big force first interacts with your rig going down the road by
pushing to the right on the left rear of your trailer, which forces the trailer
to pivot about the wheels and push the front to the left. This force to the left
by the front of the trailer is applied to the hitch point, the "hinge" in the
system. The hinge hinges like it is designed to do and applies a force to the
left on the rear of the tow vehicle. The tow vehicle pivots about the rear
wheels, and causes the vehicle to head to the right. This motion to the right is
unconsciously counteracted by you by turning the steering wheel to the left to
keep you going straight down your lane. Where is the problem? You are going down
your lane even though all these forces are just working out on your rig. NOW,
the "bow wake" of the large object passes the wheels, the "pivot point" of your
trailer, and "boom" all the forces reverse. If you follow all the force reversal
you will find out the forces are pushing the front of your tow vehicle to the
left, and you are steering to the left also to off set the force you had a
second ago before the reversal. BOOM you are in the lane to the left of where
you want to be, and possibly cohabitating with a 18 wheeler.
This small seen that gets played out hundreds of time while traveling through
heavy traffic on an Intrastate, but we hope the "cohabitation" part is never the
ending for the seen.

Now the same seen with a Hensley Arrow Hitch System.
All the same forces come to the play!! The seen starts in the same place, all
the forces start in the same places. The seen is EXACTLY the same, until you
reach the "hinge" point. The Hensley people have engineered the "hinge" out of
the system when motion forces are applied from the trailer side of the "hinge".
Now the side ways force in applied to the member in the system forward of the
trailer wheels, which is now the front half of the trailer and the entire tow
vehicle. This member has two sets of tires trying to be pushed sideways at the
same time, which is not going to take place with the size of forces generated by
a "bow wake". The driver never feels the vehicle being forced out of the
"straight down your lane" position, therefore, does not make any steering
corrections to cause them to be over corrected when the forces shift direction.
The need is not there for making the steering corrections and starting the fish
tailing and getting into trouble. The BIG difference in the elimination of the
"hinge" in the system when motion is started from the trailer end of the system.

The "hinge" is in the system in a big way when movement is started from the tow
vehicle end of the system, which makes the trailer follow very well through
turns. I have found it much easier to back the trailer into tight spots, and in
long straight moves. I have to back 200 feet out of my driveway, sense I don't
have room to turn around and keep out of the landscaping.
I was truly impressed with the lack of any feel of the normal side forces on the
trailer/rig when passed on the Intrastate by large trucks. I was on I-75 through
Tampa 20 miles after hooking to my trailer for the first time. I was also forced
to stay below 55 MPH because I didn't have the truck broken in yet, and had to
stay below 55 MPH for the first 200 miles or risk damage to the new truck. This
put me running at least 20 MPH below the speed of all the truck traffic, which
should have had my knuckles white up to my arm pits. I did not believe the lack
of motion, and got white knuckles any way for the first 10 to 15 truck passings,
but noticed I could not tell I was being passed until the "bow wake" hit the tow
vehicle, which is more stable with the trailer attached and loaded by the weight
through the load leveler portion of the hitch.

There you have my "sermon" on the joy of pulling a Travel trailer with a Hensley
Arrow System, from an engineer's and a long time trailer puller's point of view.

Wake up everyone and hit the "delete" key and move on to the next much more
interesting post.

Thanks for the opportunity, and hope this helps someone understand towing
better,

Joe Scudder
WBCCI # 8624