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Old 11-14-2013, 11:05 AM   #113
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So is it better to bend your hitch bar or dent your truck/Airstream when backing. Or is it better not to do either one? Inquiring minds want to know.

Have we beat this thread to death yet? Bet not.
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Old 11-14-2013, 11:09 AM   #114
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I don't think you can make contact between the TV and AS with a HH nor a PP....but I certainly can make contact with my tongue mounted bike rack. I have always made a practice of several narrow angle back and forth runs when backing into a spot. Too many things, including harsh axle and tire stresses, can go wrong. This is regardless of the hitch I was using at the time.
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Old 11-14-2013, 11:43 AM   #115
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Quote:
Originally Posted by Sean Woodruff View Post
You can get there while backing with any hitch. Backing at a severe angle is not a hitch issue. With a conventional hitch the crunching of metal is in a different location.
The difference is threefold:
- with a PP or HA hitch, the hitch is typically the limiting factor in maximum hitch angle. With other hitches the limiting factor is usually the point where the TV bumper contacts the trailer.
- it is difficult to determine how close you are to the limit by looking at the hitch unless you've marked it, which most people don't do.
- during tight turns where drawbar forces are high it is possible to cause the yoke (PP) or strut brackets (HA) to slip before reaching the stop. Typically this will happen when backing into a sloped or muddy site.
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Old 11-14-2013, 12:15 PM   #116
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Quote:
Originally Posted by Jammer View Post
The difference is threefold:
- with a PP or HA hitch, the hitch is typically the limiting factor in maximum hitch angle. With other hitches the limiting factor is usually the point where the TV bumper contacts the trailer.
- it is difficult to determine how close you are to the limit by looking at the hitch unless you've marked it, which most people don't do.
- during tight turns where drawbar forces are high it is possible to cause the yoke (PP) or strut brackets (HA) to slip before reaching the stop. Typically this will happen when backing into a sloped or muddy site.
Maybe the topic for another thread but a serious question for a customer...

Would you recommend that we cut the stop shorter, increasing the turning radius, so that anyone using a 3P hitch will come in contact with the frame or the trailer in those situations?

I'd have to test how much shorter I can get it.


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Old 11-14-2013, 12:26 PM   #117
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Hi Ron, I'm not sure if you are agreeing with me or not...or if I was not clear. I mean that I don't believe it is possible to reach the max rotation of the HA or PP WHILE TRAVELING FORWARD due to wheelbase and TV turning radius limitations. You certainly can get there while backing.
Rich, I agree with all you said.

I provided the link to Steve Rankin's post as a graphic and quantitative example of your statement, "I think that bind could only occur upon backing very sharply."

Ron
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Old 11-14-2013, 12:47 PM   #118
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I see this problem as a result of a new individual to towing and being the unfortunate victim of Jackknifing.

In general it is very unfortunate that those new to towing are often not schooled in the general aspects of towing and are left to learning by experience. Yes all towing configuration can reach a point of jackknife while backing up. And yes the likely hood is a function of TV wheelbase, shank length, and hitch shank length. There is little if anything that can be done to eliminate this while using any type of hitch that uses a direct ball to coupling configuration.

What I find disturbing is the fact that a jackknife point can be reached earlier while using a Hensley type hitch. This fact is a designed in characteristic and significant effort should be undertaken to make the user aware of this. I am not sure who or how this could be accomplished but it should be.

Now back to the fact that Annie has bent her stinger. The force necessary to do this could have only been exerted by counter forces produced at the wheels of both the TV and the trailer. Those forces had to be conveyed through the frames of each vehicle. With that in mind, if the rig were mine, I would want to have the frames inspected. On the trailer the point I would assume would show deflection first is the point where the A frame enters the trailer body. Inspecting the sealant on the outside of this point should show if movement has occurred. If the TV is a framed vehicle I would look receiver first for bending and at the rear most body mounts looking to see if the marks of the mounts to the body show movement. While these point are acting in tandem, and thus sharing the load necessary to bend the stinger, they are both significantly weaker point than a 2 in. square steel shaft.
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Old 11-14-2013, 12:53 PM   #119
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Quote:
Originally Posted by Sean Woodruff View Post
Maybe the topic for another thread but a serious question for a customer...

Would you recommend that we cut the stop shorter, increasing the turning radius, so that anyone using a 3P hitch will come in contact with the frame or the trailer in those situations?

I'd have to test how much shorter I can get it.


-
I vote no. Would much rather replace a stinger than visit the auto body shop or the AS body shop.

For me, however, I'll continue my narrow angle backing practices and won't have to replace/fix anything.
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Old 11-14-2013, 01:27 PM   #120
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So is it better to bend your hitch bar or dent your truck/Airstream when backing. Or is it better not to do either one?---
Doug, it shouldn't be necessary to do either.

With or without a spotter, the driver should be able to tell when the TV and TT are about to make contact. Denting your truck/Airstream when backing is relatively easy to avoid.

Bending you hitch bar when using a 4-bar linkage hitch is more difficult to avoid unless the driver has been educated about the angle limitation.
As Steve Rankin's photos show, it is not obvious when that angle is about to be reached unless the hitch has some markings and the driver knows what they mean.
And, as Steve's photos show, the hitch limit can be reached with good remaining clearance between TV and TT and with no obvious interference between hitch components.

Ron
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Old 11-14-2013, 01:56 PM   #121
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For anyone who wondered what the "ripple" in an earlier post may have been you can actually zoom in and see the paint on the chain. I know there are quite a few people who do not believe the chain is strong enough to cause any damage but here is some more evidence for the judge.
The evidence I see in that photo shows "ripple" damage which might have been caused by a properly-routed, but too-short, chain.

The damage appears to have been caused when the TV and TT were aligned nearly straight ahead.

The chain might have been pulled too taut if the rear tires of the TV were in a dip or if the TT was being backed up an incline with the TV on the level.

The "evidence" I do not see is any marking on the driver's side WD bar which would indicate a tensioned safety chain was dragged across the top of the WD bar.

It does look like some paint has been removed from the inside of the passenger-side WD bar -- such as might have been caused by a safety chain which was properly routed between the two WD bars.

Ron
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Old 11-14-2013, 02:52 PM   #122
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Quote:
Originally Posted by Sean Woodruff View Post
Maybe the topic for another thread but a serious question for a customer...

Would you recommend that we cut the stop shorter, increasing the turning radius, so that anyone using a 3P hitch will come in contact with the frame or the trailer in those situations?

I'd have to test how much shorter I can get it.


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If the Propride has the same turning angle as the Hensley then I would vote NO. Hitch components are far easier to replace than damage to the TV or trailer.
The bending of the stinger seems like it is no more than a person who is not experienced in backing a trailer (no offense to newbies - we were all there once).
I have backed my trailer at many extreme angles, made highway U-turns and have never touched the tow vehicle to the trailer or bent any hitch components.
The driver must keep control of the trailer when backing or use a long arc sweep if doing a U-turn - common sense. If you get into to tight of a turn then you must stop. Experience will show you to not get at an angle that is tighter than what can be easily straightened with a turn of the steering wheel. If you have ever backed a hay wagon you know what I mean.
From the pictures I doubt there would be any damage to the A-Frame but I would definitely inspect the hitch components and the welds on the tow vehicle receiver.
A manufacturer of a PPP style hitch should make mention in the owners manual that the turning radius is tighter than a standard hitch but there are limits that the operator of the tow vehicle should observe. There is also the risk of undue strain put on hitch components and trailer running gear.
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Old 11-14-2013, 03:22 PM   #123
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Now back to the fact that Annie has bent her stinger. The force necessary to do this could have only been exerted by counter forces produced at the wheels of both the TV and the trailer. Those forces had to be conveyed through the frames of each vehicle.---
Howie, you're correct about the load path -- but it might be good to try to estimate the magnitude of the forces and torques involved.

The photo posted by dkottum in post #34 indicates the vertical bar of the adjustable hitch twisted at the bottom about its vertical axis.
This means the yield stress of the vertical bar was exceeded due to a torque applied about its vertical axis.
That torque was applied via the bottom (horizontal) portion of the adjustable hitch.

If the vertical bar had a solid 2"x2" cross-section, and if we assume the yield strength of its steel is 36,300 psi,
the amount of torque required for the steel to reach the yield stress would be about 65,000 lb-inch.

However, the vertical bar does not have a solid 2"x2" cross-section.
It has several 5/8"?? holes drilled through it -- one of which is almost in line with the top of the horizontal bar which applies the torque.
Presence of the holes means the vertical bar has less torsion capacity, but let's assume it could handle the 65,000 lb-in of torque.

When the ProPride hitch reaches its angular limit of approximately 83 degrees, the two linkage bars become parallel to each other, and the TV is trying to push the trailer sideways.
The TT's tires generate a sideways load on the TT to counter the pushing of the TV.

If we assume the distance from the vertical bar of the adjustable hitch to the midpoint between the axles of Annie's TT is 220", the force exerted by the TT's tires to produce a torque of 65,000 lb-in would be about 65,000/220 = about 300#.

Quote:
With that in mind, if the rig were mine, I would want to have the frames inspected. On the trailer the point I would assume would show deflection first is the point where the A frame enters the trailer body. Inspecting the sealant on the outside of this point should show if movement has occurred. If the TV is a framed vehicle I would look receiver first for bending and at the rear most body mounts looking to see if the marks of the mounts to the body show movement. While these point are acting in tandem, and thus sharing the load necessary to bend the stinger, they are both significantly weaker point than a 2 in. square steel shaft.
I would not be concerned about either the TV's frame or the TT's A-frame or body.
It appears that the vertical bar of the adjustable hitch was the weak link in the system because that's where the obvious yielding occurred.

However, I would have the TV's receiver and attachment points closely inspected for signs of cracking.
The receiver and its attachments should be able to handle the roll-axis torque due to tongue weight and weight distribution,
but I don't know if they are designed to handle the amount of yaw-axis torque which caused the vertical bar of the adjustable hitch to yield.

Ron
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Old 11-14-2013, 03:24 PM   #124
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Doug, it shouldn't be necessary to do either.

With or without a spotter, the driver should be able to tell when the TV and TT are about to make contact. Denting your truck/Airstream when backing is relatively easy to avoid.

Bending you hitch bar when using a 4-bar linkage hitch is more difficult to avoid unless the driver has been educated about the angle limitation.
As Steve Rankin's photos show, it is not obvious when that angle is about to be reached unless the hitch has some markings and the driver knows what they mean.
And, as Steve's photos show, the hitch limit can be reached with good remaining clearance between TV and TT and with no obvious interference between hitch components.

Ron
I don't know if this is true.

With an 85 degree limit the ProPride may actually be able to turn as much or more then a conventional hitch without damage due to the extra 8-12" of clearance between the coupler and TV rear bumper.
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Old 11-14-2013, 03:57 PM   #125
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I don't know if this is true.

With an 85 degree limit the ProPride may actually be able to turn as much or more then a conventional hitch without damage due to the extra 8-12" of clearance between the coupler and TV rear bumper.
I agree with what you say.

What part of what I posted do you think might not be true?

I think we're saying the same thing.

Ron
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Old 11-14-2013, 04:05 PM   #126
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Question Ok...

....ask the obvious question.

How many of us towing with the HA-Pride has ever reached the point of... "can't go no further?"
I know I haven't, backing, turning or whatever.
Rare occurrence.
Consensus?
The bent stinger was in fact caused by passing the limit....consider the lesson learned, cover it in customer orientation, store it in your memory banks and Stream Safe.

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