bettered
Explorer
Joined 21 years ago
User Profile
User Widgets
All Activity
Re: Hensley Arrow: How does it REALLY work?
Stressor wrote: Bettered, you are another one who needs to buy a clue. :B There are opinions, and there are facts. The design of the Hensley Arrow uses double taper roller bearings to secure the links to the upper and lower elements (the front and back links of this 4 bar linkage.) The method of operation and application of roller bearings has been around longer than you yourself Milt. It's a proven design for securing members that rotate. There is certainly no wild theorem as to how they might work, the technology exists and has been a part of accepted design practice for well over 50 years. You are free to argue your opinions and theories in the confines of your classroom, where you are the arbitrar of the grades your students receive. But in the real world, your opinions and theories can be readily tested by thoughtful people with far more experience than I. You may pronounce a grade for me on this exam, but it really is of supreme indifference to the world or how it really works. Cling to your opinions as you will, but facts are always stronger than opinions. Was it the students who coined your forum name? Just curious.1.7KViews0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
robsouth wrote: Seems to me that if I thought I needed a HA, I would be inclined to switch to a 5th wheel and be done with it. I cannot imagine paying the price of an HA. I have never needed one and don't expect to. JMHO. Sorry Rob. I can only hope to encourage you to trade in your TT for a 5er and then tell us how much you saved over the cost of an HA. But with a 22' rig, you're probably right, you may never wish you had an HA. At least I hope not.1.7KViews0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
Stressor wrote: The lateral force is applied to the whole rig under those conditions, because the Hensley linkage is locked up tight, and with the exception of whatever play there is in the components, the rig is as stiff as a two inch steel bar can be stiff. If you actually own a Hensley Arrow, you can demonstrate this to yourself on your next outing. Drive along and watch the rear end of your trailer for a while. Stop for a break, and while you are there, loosen the struts on the Hensley by a turn. Drive on, and watch the rear end of your trailer. You will see movement that was not there before. In a locked linkage, there is no virtual pivot point. Steering input from the tow vehicle unlocks it, and as soon as things straighten out, it is locked again. The trailer cannot exert a yaw force in a Hensley equipped rig. Check out the Hensley web site, they explain how the hitch "actually works" very clearly. :B The links between the upper and lower components of the hitch are fixed in place about their axis of rotation by double tapered roller bearings (both top and bottom) in the hitch, entirely similar to the way wheels are mounted on axles. If this system operates as you've suggested, why don't we have cars driving down the road suddenly "locking up" and skidding out of control to a panic stop. With millions of cars on the road, surely one of them would have experienced lockup by now.1.7KViews0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
bettered wrote: Interesting observation. With my hitch, I don't get that "initial" wave at all. Zip. The only push I feel is when the bow wave hits the front of my TV as the big guy passes me. Even then it's less of a blip when I'm towing than when I'm not. The whole rig seems more stable towing with the Hensley than not towing at all. Go figure. RonGratz wrote: Ed, When a bow wave exerts a right-directed force on the rear of your TT, the TT responds by exerting a left-directed force on the TV. With a conventional hitch, the force is applied at the ball. The force will push the rear of the TV to the left and the relatively large resulting steering moment will cause the TV to yaw CW. It is primarily the yaw which is sensed by the driver. With the HA, the lateral force from the TT is applied to the TV at a point closer to the TV's rear axle. The steering moment is considerably reduced and the yaw of the TV also is considerably reduced. The yaw might be reduced enough that the driver does not notice it. As for the TV seeming to be more stable when towing, this could be due to the TT acting as a "yaw damper" for the TV. In order for the rear of the TV to be pushed to the right, the TT must undergo a CW yaw. The TT's yaw moment of inertia will resist the lateral push from the TV. This resistance will counter some of the bow wave force on the TV. Therefore, the response of the TV should be less when towing. At least, that's how I figure it. Ron I completely agree.1.7KViews0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
Ron, you're too much. Logic trumps feel good opportunism once again. I'm not going to take out my shear bolts to find out what happens, but then I remember cranking on those u-bolts. It would take an awful lot to make them slip. Like a TT in a 90 degree turn. Fortunately I've never owned a TV with a wheelbase short enough to get to the limit. I'm still skeptical that SFDon actually got them that tight.757Views0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
Hi Ron. I don't know how he could have made both brackets slip if they were properly installed. Once the compression force was relieved on the one side (by the bracket slipping) there would have been nothing in compression on the slipped side to force the other side bracket rearward. The actual shear capacity of the bolts is not particularly meaningful because the torque on the U-bolts is what restrains the brackets. The shear bolts have no practical mechanical function. They are extremely mild steel on purpose. Ed758Views0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
6MISFITZ wrote: Sfdon, congratulations on the hitch. I thought those strut bars were under tension, not compression. Once the brackets are shear bolted and U bolted, the strut bars are under tension, right? The brackets merely offer the struts something fairly firm to push against. The purpose of the struts is to keep the hitch from pivoting on the ball. They might have been designed to work in tension and the effect would have been similar, but as you can tell by loosening up on the strut bar bolts, the actual design puts them in compression - as Stressor noted. When I first installed my hitch, I overtorqued the strut bolts resulting in a "overcenter" condition (like a vice grip) when the hitch would shift from right to left or vice versa. It took me a little while to figure it out, but once I reduced the torque it's been working fine ever since. Even under those conditions though, my brackets have never slipped. 6MISFITZ wrote: If you exceed the turn limit of the hitch (forward or reverse) and approach 90 degrees between tow vehicle and trailer, those shear bolts are designed to shear allowing a bit of motion in the brackets, saving the hitch and its components. Exactly correct Mike. The bolts shear with primarily one purpose - to provide a visual indication that the brackets have slipped for one reason or another. The service folks told me that under normal conditions, you might never know you'd experienced a bracket that had slipped without those bolts. 6MISFITZ wrote: With our old Equal-i-zer hitch I could get to a full 90 degree turning angle with the trailer without damage. If I exceed the 82 or 85 degree maximum turning limit of the Hensley, I will most likely need an emergency repair kit. Would it be fair to assume you already know that Hensley will be only to happy to fix you up? I bought the kit for about $30. It's got a myriad of pins and clips as well as some extra bolts and a couple of zerk fitting combo gizmos for the spring bars. 6MISFITZ wrote: For now, I make sure the gas stations I enter have an easy exit or I wait for the next station with more room, so I don't test my installation! Mike. That's not something I've been worried about. Maybe because I'm a box frame type. I really appreciate your commentary about your earlier experiences. Keep up the good work, Mike.756Views0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
sfdon wrote: I mounted the frame brackets with u-bolts, installed the spring bars and installed the strut assemblies. I did not install the two 5/16" shear bolts into the frame brackets. The shear bolts are little more than an indication that the frame brackets have shifted (thus shearing the bolts). They are purposely made of low grade steel for this reason. It's not a good idea to replace them with higher grade bolts because you're preventing the safety feature from working as designed. sfdon wrote: I approached the 90 degree turn and had no problem, but when I approached the stop sign at the intersection I heard a clunk coming from the hitch. I pulled over and found that the frame brackets had shifted rearward about a 1/2" on both sides. I concluded the following: The strut assemblies are in compression. Actually it is a very cleaver design, requiring no external tools. When I applied the brakes going into the 90 degree turn, the instability of main hitch assembly under braking and turning conditions was enough to overload the struts, causing them to shift on the frame. Nope. You may have overstressed the installation when you turned more than 85 degrees. That's one situation in which the frame brackets will shift. sfdon wrote: The clunking sound was the hitch assembly flopping around because of the loose struts. My experience seems to substantiate what Ron and others have been saying. There are a bunch of questions. Instructions say to tighten u-bolt fasteners to 45 ft. lbs. What force on the struts would cause the brackets to slide on the frame? You will find that the lug nuts on your wheels are in the same neighborhood. 45 ft # is a LOT of torque. You will probably get some localized deformation of the tongue - mine are rectangular and I've noted a little. The brackets sliding on the tongue are a last resort outcome. I've never experienced my brackets sliding, although I've heard the system clank from time to time. I'm not familiar with the special requirements of non-rectangular structural tongues. sfdon wrote: What is the shear strength of the (2) shear bolts, resulting in a total resisting force to prevent the sliding to occur? It's very low - probably 35,000 psi or less. sfdon wrote: Finally, what event could occur that would cause the shear bolts to shear and the bracket to slide? You've experienced (or caused) one such situation. Another might be the link collapse / hitting the stop phenomenon described on the previous pages. sfdon wrote: Question: is there any evidence that Hensley-Arrow monitors these treads and responds to them? I would hope they would be actively involved as I believe it would help their sales efforts. You should call the Hensley service folks and discuss with them. What you experienced is not something I would expect. It sounds to me as though you may not have reached the 45 ' # of torque specified. Near the limit when the brackets were breaking loose at the specified torque, you might have noted some groaning or popping that would have alerted you to something being amiss. The fact that both brackets moved adds some logic to my suspicion about the installation. From what we can tell, Hensley is selling all the Arrows they can make, so I wouldn't worry about it on that side. What you've experienced is out of the ordinary. sfdon wrote: Posting to follow on brake controllers with HA. Lastly, as I wanted to install the HA myself, I knew that I was not going to lift up the 100# Main Hitch Assembly. I devised a hoist consisting of a collapsible saw horse on which I mounted a small boat winch. Not only did it work well, it is possible to take it with me on trips in case I have to or want to remove the main assembly. If you are interested, I can e:mail you photos. Don You might find it easier to use a floor jack. I jacked my hitch up, secured it with some blocks, lowered the coupler down onto the ball in the hitch with the TT tongue jack, locked the coupler on the hitch on and then raised the trailer to clear my blocking. As you know, the hitch normally "hangs" on the ball. Overall, my hunch is that you're experiencing problems of an unsatisfactory installation. Under normal circumstances, the frame brackets will not move and generally, they shouldn't.756Views0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
Ron Gratz wrote: I have stated previously (and Tim Luxon has confirmed with his diagrams -- somewhere back around Page 6) that, due to the HA's linkage geometry, the VPP moves about 20" to the side of the TV's longitudinal centerline when the angle between the TV and TT is about 4 degrees. Ron Wow! Thanks for the clarification Ron. At risk of re-opening the thread on a technical level, I'm wondering if the geometry/resultant force issue becomes critical as a result of the VPP's lateral travel reaching its extreme OR if it becomes significant when "hitting the stop" (collapse of one of the two links) occurs, causing a "jerk" load on the TV's rear wheels as was Garfield's experience. My expectation (not my experience) would be that the latter would be a more likely LOC event.677Views0likes0CommentsRe: Hensley Arrow: How does it REALLY work?
Maybe Milt's comment should be appended with the phrase: "...up to the limits of adhesion." Under normal circumstances, most of us are not skidding down the road, but when either the TT or the TV start to skid, unusual things happen. Milt, that's the realm we're in here. This recent discussion is all and only about "slippery conditions." The Hensley can only "hit the stop" when either the TV or TT (or both) is skidding. And I know there is no "stop." People who use this phrase are talking about what happens when the links interfere at their limits of travel. You may be old and wise, but I've still got about 5 years on you. Ed650Views0likes0Comments
Groups
Travel Trailer Group
Prefer to camp in a travel trailer? You're not alone.Mar 01, 202544,026 Posts
