New Andersen WD hitch

eb145 wrote:


So if you have a 8,000 lb GVWR trailer, the ball and coupler MUST be able to handle 24,000 lbs. of force in either direction (forward or reverse). I think the force on each chain from compressing the bushing for a heavy trailer can be around 1,000 pounds per chain.

This means 2,000 pounds of force (more or less) is applied to the coupler (1,000 lbs. per chain) that is rated for 24,000 pounds of force. This seems like a pretty good safety margin. But again, these are calculations (that I think I got right) - only time will tell for sure.
Ed

Hi Ed,

Welcome to the discussion! When you came up with 1,000# per chain load, what are the assumptions surrounding this?

- TT loaded tongue weight
- Rear overhang on the truck (ball to center of the rear axle)
- Truck wheel base
- TT ball center to TT front axle center
- Your "target" for returning the front end of the TV from WD from unhitched weight

On this post of this thread, page 2 John's calc's I backed into an approx chain force on my camper and truck setup with a simulated 1,000# and 1,400# loaded TW. I was targeting returning the truck front end back to slightly above unhitched weight, ~ 100# lighter

I backed into this on how much torque needs to be created in the receiver by a conventional spring bar WD hitch and then recreated that using an approx fulcrum length of 8" on the Andersen. I am significantly more then your 1,000# / chain.

Naturally this is all based on what assumptions are used. I'm not saying 1,000# is not correct in your case, just it was very different than what I came up with. While you are sorting this out for yourself, I am just trying to help make sure you did not miss something. Or to help correct my missed assumptions.

On the ball coupler, I tried to connect with coupler manufacture of my brand coupler. After 3 tries, getting the same admin who said she gave him the message and he never called back...well, I gave up. I understand, this guys wants to know our design specs on some new hitch out there and I don't have time for this....

By the specs, the latch side of the coupler can take as much as pulling forward. I have read the spec myself, and it was pretty clear. And yes I know they are lab tested in the way the test was done. Just to date, there are not many, (if any) other than the Andersen towing by the WD chains of the hitch and having those "constant" forces that alternate as you tow down the road into the coupler latch. If any one has fatigue data on a ball coupler latch, forward or reverse, please help point us to it.

I know about FEA model simulation as I am exposed to it often/daily in failure analysis. It is a very proven and accurate science. However I also know it is only as good as the inputs to the system. If you do not know where all the forces are coming from or their magnitude, the end result of the FEA can point you in a misleading direction. Ideally, create the model, apply all your knows, run the simulation and then, go strain gage the entire system and confirm the real known forces under use. Now you tweak the model for actual forces in the field and increase the confidence you have it right. This costs a lot of money, I know.

The RV industry has found out many times when working towards new light weight trailer A frames, trailer frames etc. The extra saftey factor of years gone by got them through, until they removed some of it by accident down sizing components, gave them to the open public to use and wow, how did they do that....

Point: As you work your way through this decision, you will need to sort through the ball coupler decision and WD ability for your rig.

The reports by users on the camping forums have been mixed. Many to most all have reported a positive increase in the smoothness of towing. They should, as the urethane has that going for it as a force dampener. Actual WD on the TV for higher TW's within the rating of the Andersen is the area of most controversy. Campers with lower TW's have done well. Higher TW's, some have had issues getting to what they feel is proper WD on the truck. A limited few with higher TW's have reported failure of the urethane under load.

I myself do not agree with Andersen's concepts of how they declare what is proper WD. It is only my opinion, not anyone else's and the user/owner of the hitch needs to come to grips with this for their TV and TT combination.

Good luck as you sort through this, if you get one, please report back. Curious to always learn more.

Hope this helps

John