Towing my 3023 w/kia sedona

[Denny_A]

Originally Posted by rickst29

"Tongue Weight" appears to the vehicle as both torque (not just "dead weight&quot on the two axles. .........snip......

.....a whole bunch of arm waving.

The attched pic shows that when the spring bars of the WDH are cinched to the trailer frame, they apply a DOWN force on the frame. The amount of down force xferred to the trailer axle is proportional to the spring bar length and distance from ball to trailer wheels.

The torque created at the hitch, beneath the ball, applies a CCW rotational moment. The moment, in turn transfer downforce to the front axle of the TV. The down force on the front axle results in an unloading of the rear axle of the TV. If done correctly (assume 600 lb tongue weight), 200 lbs down load is redistributed to each the the front TV axle and trailer axle. Result is that the hitch ball only has 200 lbs of down force acting on it, rather than the 600 lb tongue weight.

The attached .jpg makes it visually clear. Note that BEFORE attaching the spring bars to the trailer frame, all 600 lbs is acting on the hitch! Therefore the front axle is UNLOADED; diminishing steering effectiveness. After configuring the WDH, 2/3 of the downforce has been removed!

In this condition, i.e.no WDH, then no matter what one does to the rear axle (better springing or air bags) the problem of the reduce steering effectiveness remains.

Denny_A

[rickst29]

Yes, most of the torque being generated at WDH head (within the sockets of the bar ends) is simply being transferred forwards into the shank, NOT going upwards into the hitch ball (where it would increase the force, in pounds, against the coupler).

But I'm sure that it's certainly NOT as simple as "The weight which doesn't go on the front tires or the TM axle still rests on the ball"-- although your TV's rear axle is handling 200 lbs of WEIGHT, it is doing so partly as a result of a torque moment, just like the front axle-- the hitch ball is not centered above your rear axle and the "dead weight" previously located at the hitch ball is being converted into axle loads via many forces and arms of Moment within the WDH.

It's complicated to figure out exactly, because the chains do have some moment of downwards torque happening on the frame's coupler (pulling it down into the hitch head and ball). After your trailer tires have responded to the torque load by taking more weight, the front of the coupler "rests" down a bit, onto the ball. I'm guessing that the angle of the head is an important factor in managing the vertical (ball and coupler) versus horizontal (TV shank) distribution of the twisting forces from the tow bars, but the math is a ways beyond my ability.

As we all know, a 600 lb tongue weight wasn't a 600 lb axle weight when loading a trailer without a WDH-- the front of the TV was unloaded, and the rear axle was handling a lot more than 600 lbs.

The math is really bad. My head hurts. But thanks again for picture; I'll guess that the changes in weight at the hitch ball are designed to be very small when the head angle is correct and the WDH is properly set, because having the coupler loose from the ball would be a Bad Thing(tm).

[Denny_A]

Originally Posted by rickst29

.......snippity do-da...

The math is really bad. My head hurts. .

It ain't that bad. It is simly a "sum-of-moments = 0 " equation, centered on the spring bar attachment points under the hitch ball. Works for both the traier and the TV. The old FBD (free body diagram) method.

Denny_A