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Norrie46 · 12-08-2015, 05:24 PM

Ron I was thinking what you said about Pitch Axis and am curious how the hitch controls the loads created when the axis of the trailer and truck change on this axis.
As you correctly asked in an earlier post, " did we encounter any steep ramps on the BC ferries", this would change the axis or try to and the loads would be transmitted back from the truck through the hitch bar and into the bottom section of the hitch. They would then go up through the connecting links into the top section and to the ball. The movement between the ball and the trailer is restricted by the struts so where do the loads created by the pitch axis change go. As far as I can see they are taken up bey the connecting links. This is why Hensley install self aligning roller bearings in this area .
Does this ramble make any sense to you.

Norrie

Norrie46 · 12-08-2015, 05:31 PM

Thanks Jim Fowler for sharing your Hensley failure. I am sure there are a lot more out there that travelers have had repaired but never mentioned to anyone. Some people get a little self conscious about mentioning these things or brush it off as something that just happened. Especially if they paid a lot of money for it.
If this had happened in the automotive business there would have been a recall.

Norrie

Ron Gratz · 12-09-2015, 09:19 AM

Norrie,

You're correct about the load path from truck to ball, and your explanation makes sense to me. The links are a critical part of this path.
The struts prevent any relative yaw-axis rotation between ball and coupler, but do not prevent relative pitch and roll.

The links transmit vertical loads via shear forces.
Pulling forces induce tension stress and braking forces (assuming TT is pushing forward against the hitch) result in compression stress.
Pitch axis torques result in bending moments in the links.
Resistance to "sway" generally is provided via tension in one link and compression in the other.

One scenario in which a link might get bent as shown in your photos, would be the TV/TT traversing a "dip" where the TV's front tires and/or the TT's tires are higher than the TV's rear tires.
This causes increased curvature and increased loading of a the WD bars.
The bars generate an increase in CCW (viewed from driver's side) torque which can be transmitted to the connecting links.
Whether this excess torque is ever likely to cause bending of the links is very hard to estimate.

Another scenario which can result in unusually high linkage stresses is when backing the TT into a large angle (close to 90°).
At this point, the linkage is trying to push the entire TT sideways.
However, in this case, I would expect to see strut bracket shear bolt failure rather than bending of the links.

I hope your hitch problems are over.

Ron

Norrie46 · 12-10-2015, 12:54 PM

Thanks Ron. Excellent description of the mechanics of the hitch. I detect a lot of experience and knowledge in these words.
I am inclined to think the dip in the road may have caused it but this brings up long term concerns about the limit of the pitch axis angle of the hitch. I also think the material spec for the links may have changed and they are using a lower quality of steel for this part. Time and distance will tell.
The repaired, re warrantied hitch is due to arrive today so we can get on the road for San Diego. I will be monitoring the hitch continuously.
Thanks for all your advice and comments and thanks to all the post contributors.

Norrie

BoscoMN · 12-11-2015, 10:02 AM

I'm researching hitches and am considering the Hensley Cub for my 2015 19' Flying Cloud. Not anywhere the weight/length of your trailer but it is a much lighter version of the Hensley Arrow. Now I wonder if some situations may result in a bent hitch like you had experienced. Does anyone have experience or advice on the Hensley Cub hitch?

switz · 12-12-2015, 06:22 AM

The draw back to the "CUB" model is a very limited upgrade path on trailer size and weight if the owner gets a severe case of "two foot itis" and wants a bigger trailer in the future.

Then the lower initial cost of the "CUB" is negated by the additional cost of acquiring the larger Arrow model.

We are using the Arrow we had on the 25FB on the 23D and it works fine.

RinconVTR · 12-12-2015, 10:52 AM

In reference to the Hensley's being bent and common repairs, I can confirm from my own experience, they do A LOT of repairs. However, in some cases, the issue will go unnoticed and/or Hensley will call it normal. I will show you via my own personally pictures. Many of these failures cannot occur on the Propride, as the differences in the design eliminates some of these components...like the strut bars and multiple pins.

Bent strut bar...on its way back to Hensley. This is how it arrived FYI.

A common strut failure at the mounting point and improper repair not allowing the strut pin to fully seat, thus blocking access to the locking clip hole. This is yet another "as received" defect.

Below are 3 of my own pics and then one not mine, showing where another specific failure mode ends. It was this final straw that broke the camels back, and I returned my hitch back to Hensley.

What your looking for is air gaps between steel plates and how they are no longer parallel. The caliper measures an 1/8" bend in the plates, which will only get worse over time, or fail on the road.

This could potentially happen to the Propride as well, but I have yet to see it.

This pic is not mine...but I have collected many like it. Its where mine was leading.

PKI · 12-12-2015, 12:44 PM

How much of a Pitch/Dip can a pivot point projection hitch transit without incurring damage? Pat

dkottum · 12-12-2015, 01:10 PM

Quote:

Originally Posted by PKI

How much of a Pitch/Dip can a pivot point projection hitch transit without incurring damage? Pat

That would depend on the stiffness of what else is taking the pitch/dip, your trailer A-frame and the truck's receiver, and the amount of truck and/or trailer load applying pressure, as well as the speed at which it happens.

Enough pitch/dip and somethings got to give. I've read of some trailer A-frames and truck receivers being bent, and why some people have their tow vehicle receivers reinforced. It's a reason we load as little as possible behind our truck's rear axle, and try to keep our trailer hitch weight low.

Best to avoid it, if too severe an angle perhaps loosen the weight distribution to allow more flexibility under you've gone over it.

PKI · 12-12-2015, 02:05 PM

DK - thanks for taking a shot at it. Any idea how much is too severe? Pat

rmkrum · 12-12-2015, 02:17 PM

Not to be snarky, but if the hitch WD bars drag or the back of the truck looses traction from being lifted up, that's probably too much of a dip or hump.

I try to find as level a path as possible to hopefully avoid scuffing the WD bars (yeah, they need painting again) or lifting the truck rear too much. If I'm in doubt, DW or I get out and looks at the situation. Sometimes you guess wrong and get noises😖

I do want to lift the AS up a bit because it's marginal now, and the new TV is a bit taller. A couple inches will help with driveway approaches.

Sent from my pocket Internet using Airstream Forums

dkottum · 12-12-2015, 02:22 PM

Quote:

Originally Posted by PKI

DK - thanks for taking a shot at it. Any idea how much is too severe? Pat

I have no idea, but I've seen gas station approaches that I have stayed away from where the roadway drops to almost a ditch, then back up again sharply into the station. Someone mentioned a ferry landing earlier, that might be quite a ramp.

switz · 12-13-2015, 08:41 AM

If a defective or worn part is replaced under the "lifetime" Hensley warranty with an unusable replacement part with the part travel expenses both ways born by the owner, does Hensley eat the freight both ways to replace the the unusable "replacement" part with one that works?

When I get home, I will inspect our Hensley hitch head on the 23D for these out of alignment issues that are clearly shown in the photos above. Thanks to RinconVTR for helping to visually clarify the written explanations.

Norrie46 · 12-13-2015, 05:40 PM

This failure is similar to the ones that Can Am London Ontario CA mentioned to me. That is why they were reinforcing this area where the load of the WD spring bars is concentrated.
If more forum contributors reported these and other problems maybe Hensley would come up with modifications that would solve them.

Norrie

NoResults · 12-13-2015, 06:53 PM

I am sure glad I am reading this prior to purchasing my trailer. There are a lot of other manufacturers. Hope they and there dealers are better.

RinconVTR · 12-14-2015, 07:24 AM

Within the first 60 days, Hensley will pay for replacement part shipping (actually, they charge/refund you and send you a pre-paid label). After that, you pay shipping to get it there, and from the manual...it sounds like you pay to get it back as well.

"Customer is responsible for all freight charges associated with warranty work."

switz · 12-14-2015, 07:41 AM

So, if Hensley sends out a defective replacement part as shown in the photo of the orange head, the customer is responsible for the freight to return that part and get another one paying the freight?

The hitch head alone generates about a Ben Franklin freight bill each way.

Sending out a defective replacement part is not fulfilling a warranty and the round trip for such part should be the vendor's responsibility.

I will have to hope that a lighter trailer like the 23D (6,000 pounds GVW) does not stress this design too much. They had 1,400 pound weight distribution bars available, so one would expect a 1,400 pound tongue weight to be within their design parameters as they claim support for trailers weighing 14,000 pounds.

A ProPride replacement would always be an option and it's initial cost is less than the Hensley price.