[A/S] Lane Changes (Was: Sad News)

["Maurice Riggins" <maurice.riggins@xxxxxxxxxxxxxxxx>]

Lane changes CAN INITIATE SWAY!  Especially with a conventional hitch.

Let's look at the mechanics of what happens when you are going down 
the road and a person or animal steps into it from the right side and 
you crank the steering wheel to the left hard.  The front of the tow 
vehicle moves left with respect to the rear axle and the tail moves 
right with respect to it.

With a conventional hitch, when you turn left, the trailer first 
turns right toward what you are trying to avoid, then with further 
forward motion, gets pulled back across the straight line of former 
travel to the left. In essense, it has made the bottom half of an S 
turn that can initiate sway, and at the same time has gotten closer 
to what you are trying to avoid.

With a Pullrite hitch, pivoting at the rear axle, the trailer remains 
in forward motion until the tow vehicle rear axle begins moving left 
of the straight line of former travel. Regardless of how hard the 
swerve, the trailer remains in a straight line until time to turn 
left.

With a Hensley, the front of the hitch moves to the right with the 
rear bumper of the tow vehicle, while the rear of the hitch stays 
with the trailer in a straight line (that's how a Hensley turns), but 
if the swerve of the tow vehicle is severe enough, the rear can 
travel more to the right than the hitch does when turning, and there 
can be a little of the trailer turning right before left, it's just 
reduced considerably from that of the conventional hitch.

When you straighten out in the left lane,

With a conventional hitch, the pendulum (trailer) still swinging to 
the left will overshoot the tow vehicle's path and then get back 
behind it. Even with a friction or dual-cam sway control, it may 
oscillate a few times, decreasing each time, but using the lever arm 
of the distance behind the tow vehicle rear axle to yaw it back and 
forth in the opposite direction from the trailer.  This is probably 
what happened to Tony.

With a Pullrite hitch, the trailer will also overshoot the tow 
vehicle's path and may oscillate a few times as above, but this has 
absolutely no effect on yawing the tow vehicle, which remains stable 
as a rock in a straight line.

With a Hensley, as the trailer approaches the straight line path of 
the tow vehicle, the link bars prevent it from overshooting. It may 
move the whole rig, in a straight line, over in the lane to a path 
parallel to the tow vehicle's straightline path, but it doesn't 
oppose the vehicle operator from steering to the right to prevent 
this.

This is why the Hensley does so well running S curves through the 
cones.

--
Maurice
WBCCI 5446