Questions-5th Airborne Sidewinder

[BB_TX]

quote:Originally posted by sreigle

One is the comment from some forum about stresses put on the hitch and truck by moving the pivot point back 20 inches. I just measured the offset of the pin on the extended pinbox that came on my Montana. It's 20 inches. So there is no more leverage effect with the sidewinder than with the standard extended pinbox. The sidewinder stays locked directly above the center line of the truckbed, even in a turn. So there's no unusual side stresses on the truck and hitch.

You are correct that the extended pin box has the same offset and therefore the same stresses as the Sidewinder IN THE STRAIGHT AHEAD position. But if you turn, it changes. Taking the worst case of a 90 degree turn, that 20" of leverage is now directed from the side, not the front as before. So now the torque force is also directed side to side to the frame, not front to back as before. Now obviously you will not be bouncing down the road like that, but still ????

[sreigle]

Thanks, Bill. I can see where the stress angle is different but with the standard extended pinbox, when the trailer or truck tip beyond what the hitch can swivel, doesn't the same stress apply?

And doesn't the same stress apply when using a non pivoting hitch? I know the pinbox remains straight ahead of the trailer but the forces applied in these situations would be vertical, placing upward stress on one side of the connection point under the Montana, wouldn't it?

I'm not being stubborn, just trying to make sure I understand.

Thanks.

[BB_TX]

First, think of the pin box as applying a force downward on the hitch centered at the king pin. Then think of the hitch applying an upward force to the pin box, centered at the king pin to oppose the downward force. The upward force is at the king pin. But the king pin is offset from where the pin box attaches to the frame. So there is a torque force equal to the pin weight times the offset distance equaling a torque force trying to rotate the frame member(s) it is attached to. Basic physics. That force is applied to the frame directly in the plane from front to back.
Think of it as using a "cheater bar" to loosen a tight nut. The longer the "cheater" the more force you can put on the nut with the same amount of force from your hand. Basically a multiplier.
With a standard extended pin box, the torque force of the 20" extension is always front to back on the 5er, even if the 5er is turned 90 degrees to the truck. This is true because the center of the king pin does not move in relation to the 5er. It is always offset toward the center front.
With the Sidewinder, when you turn 90 degrees, the center of the king pin is now offset 90 degrees to one side of the 5er. That is true because the king pin does not move in relation to the 5er frame. The king pin is now 20" off center of the frame on the pivoting swing arm and that 20" of torque force is applied side to side instead of front to back. So now the force is trying rotate the frame member(s) it is attached to in a side to side motion.
Going forward the force is no different. But every time you turn, even a little, there is some of that force moved from the front to back plane to the side to side plane.
Problem or not? Who can say except those who have used them for years and never had a problem.
Make sense?

[BB_TX]

Steve - You got me to thinking too much now and it is making my little brain hurt.
BUT.
Another point to further illustrate it, would be to think of the extended pin box as a see/saw with the point at which the front of the pin box connects to the frame as the fulcrum. As force is applied upward at the king pin, an upward force is applied to the front edge of the pin box where it attaches to the frame. BUT. The rear edge of the pin box would actually be trying to pull down away from the frame. An easy way to visualize that is to imagine you were to loosen all the bolts that connect the pin box to the frame by one half inch. Now as you push up on the king pin, the front edge of the pin box would push up on the front of the frame, but the rear edge of the pin box would actually slide down the bolts until it contacted the head of the bolts, pushing down on the bolts and leaving a gap between the pin box and frame.
That gives you an idea of how the extended pin box (a lever) causes a rotational force on the frame members. Again, on a fixed pin box, that rotational force is always front to back. But with the sidewinder and a turn, that rotational force is moved to the side some amount. The greater the turn, the greater the movement of the force. During a turn, the amount of force at each of the 4 corners of the pin box where attached to the frame would be changing, even changing from up to down and down to up in a severe turn.
I would assume (and hope) the frame manufacturers have taken into account the use of extended pin boxes and designed for the front to rear rotational force. I am not so sure they have designed for that rotational force to be moving from a front to rear plane to a side to side plane.
OK. I am an engineer. You can call me Dilbert.

[sreigle]

Thanks again, Bill. I understand your explanation and even remember the basics of Physics from my physics courses many years ago.

What I don't know is how the frame is structured where the pinbox is attached. I would think the builder, Lippert, would assume more need for strength in the normal straight ahead direction but enough in lateral directions to handle side stresses, twisting forces, when the truck and the trailer are not on the same plane. Particulary when the FW hitch in the truck does not articulate laterally, not a rocker. What I don't know is whether the anticipated force they frame was designed to handle would be enough for the force applied in the 90 degree scenario you described.

The Sidewinder is available only for specific pinboxes. I'm not sure whether that is because of the need to design the attachment structure to fit particular pinboxes or whether it's because those they have tested. Or both.

So far I've not found, anywhere, any complaints about problems caused by the Sidewinder. The product is relatively new, I think, but by now I would think there would be some complaints visible. I don't subscribe to the theory that no owner will speak badly of a product he spent money on. Some might not but we can just look at this MOC forum and see that theory doesn't work. I'm still looking for those complaints, though. I haven't heard back yet from 5th Airborne. I think next week it is time to call them.

[8.1al]

I know all this lever stuff can get confusing at times, but I don't believe the sidewinder will place any additional stress on the pinbox as all you are doing is moving the pivot point. The hitch however is another story. When turning with that 20" lever you are placing twisting forces on the hitch that you wouldn't normally get and that kinda scares me as the hitches are designed for front=rear and side loads.

[BB_TX]

I would think that 5th Airborne, understanding the dimensional changes in the torsional forces, would have done enough testing to convince themselves that there would be no frame problems and that there would be no potential future liability issues.

[sreigle]

I'm googling and researching and so far no problems related to stress have I uncovered. A couple of people got the wrong blocks and one had too much slop but no stress related problems so far. Two claim to have engineer friends and rv techs look at it and proclaim no problem. But this is the internet, so who knows.

Here is a picture of a Sidewinder. Trying to visualize the different stresses at different angles, it appears to me the applied stresses might actually be no different, or little different, than with a fixed pinbox because of the design of this thing. But, again, I am not an engineer nor qualified to proclaim for fact any of the above. Looking at this picture, what do you all think?

[sreigle]

Well, I called Fifth Gear this morning. I was told they've sold the entire division to Cequent Towing. I called CT. The lady who tried to help me was not at all knowledgeable. She kept trying to find answers in the online manual and had to keep asking someone else. I finally asked to talk with the someone else. He was more knowledgeable but did not boost my confidence level very much.

And I was left still a bit confused.

What I understand from this conversation about what happens if we have to be towed by a commercial vehicle or other vehicle with a different hitch than ours:

1. We could remove the entire Sidewinder and replace the original pinbox.

or

2. There were a few models made for certain Keystone products (Everest?) which have holes on top where bolts could be put through to lock the arm in the straight ahead position. This might be doable. However, only certain pinbox mounting brackets (the OEM brackets on the FW) have the holes through which the bolts could be inserted. My Montana brackets do have two holes in which bolts could be placed from the top. They can be seen by looking inside the pinbox mount from the rear. I do not know whether the sidewinder model for this hitch has the holes and they couldn't tell me.

At this point I am shying away from the Sidewinder until I can find out there is a positve method to allow safe towing by any fifthwheel hitch.

There was mention of a "universal block" on one of the websites I looked at. This universal block comes with the sidewinder. Is it possible this universal block will work to lock the arm to any fifthwheel hitch that might be used? The literature also talks about the sidewinder being designed to work with nine particular hitch models. That leaves me wondering if the universal block allows use with any fifthwheel hitch or what.

[SlickWillie]

Same company that owns Reese. I knew that back in November I spoke with a 5th Airborne rep at Camper Clinic in Rockport, TX. I was thinking he told me they had purchased Reese, but my old rememberer got me again.

I'm gonna keep my comments on the Sidewinder short. I would be worried about that 20" of metal if that fifth wheel got to "chucking" (think that's the right word). Looks like something would give sooner or later.

[scductman]

Steve I dont know about you but every time I asume it makes a a#$ out of me. But I to think it puts alot of stress on the box when turning JMHO. bobby

[BB_TX]

Looks like that acquisition actually was announced last July.
http://www.trimascorp.com/pdf/trimas...se_7_12_07.pdf. But I don't remember hearing anything about it. Like so many other companies now, it appears it is now owned by a large holding company.

[Exnavydiver]

bsmeaton, then according to your response to my last post anyone that owns a Montana and has positive remarks is spouting 99.9% bias bull and bragging???

[sreigle]

The 20 inches is actually the same length as the standard extended pinbox on our Montana. But the angles are a concern. Besides talking with the manufacturer, I also emailed one of their dealers. I got a reply yesterday saying he had called the mfr with my question and to be towed by a commercial tow vehicle I'd have to remove the sidewinder and reinstall the original pinbox. For this reason I'm dropping any thoughts of buying the sidewinder.

Now I'm going to rethink the pullrite superglide. I thought I heard there's another brand with similar function but can'r remember what it is.

Thanks for all the input and discussion. It was very helpful.

[c5racer]

Might be this one.
http://www.colibert.com/

[sreigle]

Interesting hitch, that Rail Rider, Pete. But from what I can tell it's not an automatic slider. somewhere awhile back I saw something about another brand of automatic slider, other than Pullrite.

[DL N K]

Steve,
I believe the other one you're talking about might be the Hijacker auto slider.
http://www.hijacker.com/whatsnew/pdf...to%20slide.pdf
I looked at one at the RV show in Memphis a few weeks ago. It used a large gear arrangement instead of a cam like the Super Glide.
It is, if I remember correctly, a bit less expensive that the Super Glide.
The lock-up is a bit different, there are bars on the hitch deck that are adjusted to fit closely to the sides of the skid plate on the pin box to effectively "lock" the pinbox to the deck of the hitch. No problem then for other tv's pulling the 5er since the "lock-up" adapter stays in your truck.

[sreigle]

Thanks, I'll check that out. I see there's another thread about that hitch, too.