New Andersen WD hitch

Ron Gratz wrote:

I fail to see how the tongue jack makes any difference.

Ron, LOL… OK I have stopped laughing hard enough to type now… Thanks I needed that…

I was attempting to see your point of view and review the words I used. I was more referring to the physically movement of the parts. I’ll try again but I do believe we both are now on the same page. This is somewhat a step by step progression of the parts moving when hitching up.

• If the tongue jack is down to the ground when hitching the TT to TV the coupler will only go as low as the jack will allow.

• As the coupler is lowered over the tow ball and you can then latch the coupler, the ball is captured inside and may rest in the coupler in any direction there is clearance to allow it to move in at this point. The jack is still holding the majority of the TW as you stopped lowering it once you can lock the coupler. This is no different on a standard WD hitch or the Anderson at this point.

• As the WD chains are tensioned on the Anderson the truck holding the tow ball and the trailer will draw towards each other. Either TV or TT will rolls towards each other by the amount of clearance in the coupler, the flex of the tongue jack or the clearance in the parking pawl in the TV transmission.

• As tensioning continues the back side of the ball contacts the latch side on the back side of the coupler.

• If there is zero (0) clearance between the tow ball and coupler neither part will move in relation to each other up or down. The tow ball exerts a reaction to the force of the latch pressing on it.

• Depending on the amount of clearance inside the coupler and if internal geometry of the coupler body touched the top of the ball, the tow ball would move in the direction the internal geometry and amount of clearance allowed it to.

• Now to the jack…assuming we have an average truck, 1/2 ton, to 1 ton, at least 750# of TW for sake of discussion, if the jack is supporting the TT “during” the tensioning process it is easier for the truck supporting the ball to move up or down then it would be the TT tongue. The TT has a rigid jack to the ground held down to the ground by the TW, the tow ball held by the truck is supported by springs attached to the axle and can move easier up and down the slight coupler clearance then the TT. If there is no jack then TT tongue “may’ move up on the tow ball if the internal coupler geometry and clearance allowed it to.

OK next point…..

As the chain tension increases, the forward thrust of coupler against ball increases. Whether the coupler then moves upward relative to the ball simply depends on the net direction (up or down) of vertical forces generated between coupler and ball. And those forces depend on shapes of the contact surfaces between socket and ball and between latch and ball. I don't think we can unequivocally say that "If the chain forces are high enough they will overcome the down force of the TW and the coupler will cam itself up."

Yes, you are correct. We need to leave the movement up or down out of this as all couplers are not created equal. Good point. I agree…:)

Okay, let's assume the diagram for your specific coupler accurately depicts the relative positions of ball and coupler components with springs tensioned. Then I also assume there must have been a gap between ball and coupler latch before the springs were tensioned. The tensioning of the springs then caused the coupler to move forward and upward (relative to the ball) until the coupler latch was firmly in contact with the ball.

Given these assumptions, I would guess that a relatively small forward thrust, perhaps equal in magnitude to the TW, would cause the coupler to ride up and over the ball to close the gap between ball and coupler latch. The relatively small force requirement would be due to the relatively flat slope of the socket/ball contact surface as you have depicted.

Is your coupler latch adjustable? If so, why should there be a gap between ball and coupler latch prior to spring tensioning? If there is no gap after the coupler is latched, the coupler latch cannot move forward relative to the ball and the coupler cannot rise up relative to the ball.

As I showed to Ben, my coupler has an 1/8” total omnidirectional amount of clearance between ball and coupler. If I held the ball on center of the coupler sphere there would be 1/16” daylight almost all the way around. My coupler is nonadjustable. There could be an up to a 1/8” gap anywhere in the coupler until the chains where tensioned depending on how latch up occurred. Due to my internal coupler geometry the tow ball would wedge itself into the bottom rear portion of the latch. All ball couplers may not do this even while this style coupler is common on many TT’s. As stated the only thing we can say with a high degree of confidence is the ball will be under pressure on the latch side of the coupler.

Also, even if what you have depicted for your particular coupler is an accurate representation, I'm sure there are many other coupler configurations which would produce different results. So again, I must believe we cannot be certain that coupler "lift" will occur.

Yes I agree.

But, before becoming a completely agreeable person

Ron, that’s OK after a few pages of typing we have usually always ended up agreeing. LOL :B

John, I think you were in the right league with your chain force calculations. And, given the characteristics of your specific coupler (including the gap between ball and coupler latch), I agree a combined chain tension of 7800# certainly would cause the coupler to move forward and rise the 1/8".

Thank you for confirming my thoughts.

However, although the Andersen hitch is rated for a TW of 1400#, I really doubt that they expect the hitch to generate enough WD torque to restore all the front end load which would be removed by a 1400# TW
Ron

You too…. Yes, I fully agree…. I would like to see scaled axles weights on 1,400# loaded TW TT and heavy truck

John