Blue Ox Sway Pro, how it functions against sway

[rexlion]

I've been reading about and looking at pictures of the Blue Ox Sway Pro. And I've read some of the recent threads here that discuss this hitch. Blue Ox describes the sway control as a "caster effect" but their advertising does not elucidate beyond that one descriptive phrase.

Near as I can figure it out, this caster effect is caused by the spring bar sockets being offset from the swivel point (the ball). On the other end of each bar, a chain runs upward to the trailer frame. If the trailer should sway to one side, the end of the bar on that side will travel farther along the frame in the direction of the trailer, and since the chain's length is fixed it causes the bar tension to climb, and all of this exerts a push on this side. Meanwhile the opposite (pull) is occurring on the other side. Do I understand this correctly so far?

Assuming I've stated the forces at work with reasonable accuracy, it seems to me that the push-pull forces continue to be exerted (albeit in a declining amount of force) as the trailer's angle to the tow vehicle once again approaches 180 degrees (i.e., straightens out).

The problem I see with this is the fact that an object in motion tends to stay in motion. Consider the pendulum: as it climbs to one side, the force of gravity exerts a downward pull and the pendulum slows, reverses course, and swings toward 'straight down'... but the pendulum does not stop there. It continues to arc upward in the opposite direction. Taking this example to the Sway Pro, it seems as though the trailer's motion back to 180 degrees has little or nothing stopping it from continuing its swing in the opposite direction. As the trailer sways the opposite way, the Sway Pro again exerts the push-pull force in an increasing measure until the TT's sideways momentum is stopped... and is again pushed & pulled in the other direction where it again has unchecked momentum to go beyond 180 degrees.

Without some dampening force (such as friction) to slow the momentum and avoid the pendulum effect, I don't see how the Sway Pro can truly be an effective anti-sway hitch. If someone has a different or better concept of the physics involved, I'm open to hear it (I'm not a mechanical engineer, unlike my son).

As for people's experiences while using the Blue Ox Sway Pro, I fully realize that most users are happy with it (but meanwhile, some users have experienced sway with it...and felt strongly that it was properly adjusted, too). I think that an analogy might be drawn to the many people who, over the years, have happily and successfully towed without any sway control whatsoever; in other words: it worked fine, right up until the one day when conditions were just right, and then (surprise!!) it didn't work.

Comments? Questions? Curse words? 😄

[Hannibal]

dthfsa wrote:
I battled with the Blue Ox for a year. I went as far as upgrading from a F150 max tow to a F250 with no improvement. In the end after many calls, email etc with BO I ended back at my dealer and switched to an Equalizer.
RV Tech told me that on some toy haulers and longer trailers they have had issues with sway control. Can't really predict when or on what trailer it will happen.
Some cases it works really well, others it may not. Not every hammer works for the same job.

Seems others would agree with you as well.

https://www.etrailer.com/question-116001.html

[dthfsa]

I battled with the Blue Ox for a year. I went as far as upgrading from a F150 max tow to a F250 with no improvement. In the end after many calls, email etc with BO I ended back at my dealer and switched to an Equalizer.
RV Tech told me that on some toy haulers and longer trailers they have had issues with sway control. Can't really predict when or on what trailer it will happen.
Some cases it works really well, others it may not. Not every hammer works for the same job.

[camperforlife]

rexlion wrote:
Now we are getting somewhere!

I agree that a plain WD hitch provides a slight amount of anti-sway help. And I can see how the shorter chains or straps (there's a Straptek strap set available for this hitch) would increase the amount of push against sway. But, BenK, I'm surprised to hear you say you'd choose the Blue Ox over a friction type like Equal-i-zer. Do you really feel that the Blue Ox's system would provide at least an equal amount of sway protection to Equal-i-zer's 4-point friction? Or do you just find its noiseless operation advantageous enough to forego some measure of anti-sway?

The 'Swaypro' is, as you say, somewhat similar to a plain WD hitch in that the method it uses to resist sway is a "push/pull back toward straight" in both instances. However, a plain WD hitch by itself has never been considered a very effective way to control sway (and thus the use of friction bars in conjuction with it). The Swaypro sort of seems like a plain WD hitch that's been fed steroids; it exerts a stronger push/pull toward center whenever the TT goes off to either side. Yet that push/pull force has nothing to slow down the rotation on the ball as the TT returns to straight.

In comparison, the friction sway control unit provides resistance in both directions; it slows the TT's attempt to go off to one side, and then it moderates the TT's travel back toward center. The friction system never pushes the TT faster in any direction, but instead slows and dampens the undesirable motions; it provides greater control in both directions of 'away' and 'toward' center. As we all know, dangerous sway occurs when the TT misses "center" and sways to the opposite side, then continues its back and forth oscillation. Friction sway control is always working at slowing down the off-center travel no matter which direction it's going; isn't this a more effective way to control sway than merely slowing travel away from center but allowing (even hastening) travel in the opposite direction?

The proof of the pudding, as they say, is in the eating. A true test of an anti-sway system can be seen near the extremes of towing conditions (if one sway control hitch can't meet the challenge of an extreme condition but another one can, this says something about both units). At least two forum members, owners of TT's exceeding 30', have had bad experiences with the Blue Ox Sway Pro, as mentioned in this thread: goducks10 and busterbrown73 posts . See also the experience of dthfsa . Can anyone recall reading similar accounts of sway with a properly adjusted Equal-i-zer?

I'm not even going to try and understand how it works but it does. I tow a 35 footer with a GMC 2500 and live in a high wind area. One of those areas that is littered with industrial wind turbines and blow overs is not unheard of. So I have a lot of experience towing a long trailer in the wind with a Blue OX. Guess what? It works and works well. Someone smarter than me will have to explain the physics.

[myredracer]

I wish someone out there would do a real life engineering comparison between the various WDH designs using the same truck & trailer setup and using an accelerometer and any other needed instruments. Until then we'll never know if there are any significant differences between designs and how well each works. All I know is that I love our Reese DC. Interestingly, I've only ever seen two of them in our strolls around CGs.

~DJ~ wrote:
I just bought a Blue Ox Sway Pro. Love the ease of installing and hooking up. BUT, it didn't work for me. Constantly "danced" going down the road.

Did you address the other important things that contribute to sway like correct psi in truck & trailer tires, TT level to nose down, etc.? Correct amount of weight back onto steer axle? Some will say a properly set up TV & TT combo will not sway at all and has less to do with the WDH design. An F250 should not struggle with a 27' TT with any WDH (properly set up). Never trust a hitch shop or RV dealer to install a WDH and set it up properly. Much better off learning how to do it yourself along with addressing all the related contributing factors.

[IndyCamp]

I went from a Reese Dual Cam, which I really liked, to a Blue Ox Sway Pro 2000, which I really love.

Great system, and very easy to hitch up.

[_DJ_1]

I just bought a Blue Ox Sway Pro. Love the ease of installing and hooking up. BUT, it didn't work for me. Constantly "danced" going down the road. Had to stay on top of the steering like balancing a marble on top of a balloon. When a semi was passing me it tried to suck my truck in to the side of his cab and when he went by tried to blow me off the ditch side!!

I bought it from my hitch shop and he installed it. After many phone calls back to the hitch shop and nearly 2 days out on the freeway trying every possible position and chain tension I gave up. My hitch guy is baffled. He said he sells dozens of these a year with no complaints. He also called Blue Ox for suggestions and they told him to have me disable the factory sway control. Well, I did but made no difference. And I wasn't about to disable a proven feature to trust only a hitch.

The dealer took back the Blue Ox and I am back to my antiquated Husky. At least it works.

[rexlion]

I am glad for everyone who gave input. BenK's description of how it works was better than mine, yet it pretty much confirmed my understanding of the Sway Pro.

Ralph, yes, emphasis on slight for an ordinary WD hitch.

[Ralph_Cramden]

rexlion wrote:


I agree that a plain WD hitch provides a slight amount of anti-sway help.

I think you should emphasize "slight" with a standard WDH. "None" may be a better choice of words but shifting weight from TV rear axle to TV front axle and trailer axle may or may not help a little with sway prevention, very specific to the situation / combination?

I can find you a million posts in forums where people call the spring bars on a standard round or torsion bar WDH "sway bars", which is a far stretch from what they actually do.

I have a Reese standard WDH (round bar) that was used on 4 different trailer. I added the dual cam sway control to it for one of those trailers but on the other 3 did not use the dual cam. Great system other than the noise when the cams disengage, will scare the hell out of people. Now days I just drop it on the ball and go with a 2500 truck.

[busterbrown73]

rexlion wrote:
Now we are getting somewhere!

I agree that a plain WD hitch provides a slight amount of anti-sway help. And I can see how the shorter chains or straps (there's a Straptek strap set available for this hitch) would increase the amount of push against sway. But, BenK, I'm surprised to hear you say you'd choose the Blue Ox over a friction type like Equal-i-zer. Do you really feel that the Blue Ox's system would provide at least an equal amount of sway protection to Equal-i-zer's 4-point friction? Or do you just find its noiseless operation advantageous enough to forego some measure of anti-sway?

The 'Swaypro' is, as you say, somewhat similar to a plain WD hitch in that the method it uses to resist sway is a "push/pull back toward straight" in both instances. However, a plain WD hitch by itself has never been considered a very effective way to control sway (and thus the use of friction bars in conjuction with it). The Swaypro sort of seems like a plain WD hitch that's been fed steroids; it exerts a stronger push/pull toward center whenever the TT goes off to either side. Yet that push/pull force has nothing to slow down the rotation on the ball as the TT returns to straight.

In comparison, the friction sway control unit provides resistance in both directions; it slows the TT's attempt to go off to one side, and then it moderates the TT's travel back toward center. The friction system never pushes the TT faster in any direction, but instead slows and dampens the undesirable motions; it provides greater control in both directions of 'away' and 'toward' center. As we all know, dangerous sway occurs when the TT misses "center" and sways to the opposite side, then continues its back and forth oscillation. Friction sway control is always working at slowing down the off-center travel no matter which direction it's going; isn't this a more effective way to control sway than merely slowing travel away from center but allowing (even hastening) travel in the opposite direction?

The proof of the pudding, as they say, is in the eating. A true test of an anti-sway system can be seen near the extremes of towing conditions (if one sway control hitch can't meet the challenge of an extreme condition but another one can, this says something about both units). At least two forum members, owners of TT's exceeding 30', have had bad experiences with the Blue Ox Sway Pro, as mentioned in this thread: goducks10 and busterbrown73 posts . See also the experience of dthfsa . Can anyone recall reading similar accounts of sway with a properly adjusted Equal-i-zer?

Nicely stated and I couldn't agree more.

[rexlion]

Now we are getting somewhere!

I agree that a plain WD hitch provides a slight amount of anti-sway help. And I can see how the shorter chains or straps (there's a Straptek strap set available for this hitch) would increase the amount of push against sway. But, BenK, I'm surprised to hear you say you'd choose the Blue Ox over a friction type like Equal-i-zer. Do you really feel that the Blue Ox's system would provide at least an equal amount of sway protection to Equal-i-zer's 4-point friction? Or do you just find its noiseless operation advantageous enough to forego some measure of anti-sway?

The 'Swaypro' is, as you say, somewhat similar to a plain WD hitch in that the method it uses to resist sway is a "push/pull back toward straight" in both instances. However, a plain WD hitch by itself has never been considered a very effective way to control sway (and thus the use of friction bars in conjuction with it). The Swaypro sort of seems like a plain WD hitch that's been fed steroids; it exerts a stronger push/pull toward center whenever the TT goes off to either side. Yet that push/pull force has nothing to slow down the rotation on the ball as the TT returns to straight.

In comparison, the friction sway control unit provides resistance in both directions; it slows the TT's attempt to go off to one side, and then it moderates the TT's travel back toward center. The friction system never pushes the TT faster in any direction, but instead slows and dampens the undesirable motions; it provides greater control in both directions of 'away' and 'toward' center. As we all know, dangerous sway occurs when the TT misses "center" and sways to the opposite side, then continues its back and forth oscillation. Friction sway control is always working at slowing down the off-center travel no matter which direction it's going; isn't this a more effective way to control sway than merely slowing travel away from center but allowing (even hastening) travel in the opposite direction?

The proof of the pudding, as they say, is in the eating. A true test of an anti-sway system can be seen near the extremes of towing conditions (if one sway control hitch can't meet the challenge of an extreme condition but another one can, this says something about both units). At least two forum members, owners of TT's exceeding 30', have had bad experiences with the Blue Ox Sway Pro, as mentioned in this thread: goducks10 and busterbrown73 posts . See also the experience of dthfsa . Can anyone recall reading similar accounts of sway with a properly adjusted Equal-i-zer?

[gmw_photos]

To add a photo for graphic effect of part of what Ben is saying above, this pic is obviously looking straight down onto my blue-ox ( I have the old style, that has adjustable angle of the head ).

I did an eyeball kinda measure with a couple of straight edges, and it appears the center of the trunnion pivots is approx 5/8" ahead of the center of the ball.
From the center of the trunnion pivot back to where the chain attaches to the weight bar is 29", so I'll leave it to one of y'all to figure the angles and effective length changes and all the force vectors (what's our vector, Victor ? Got clearance Clarence ? roger, Roger ).

[BenK]

Answering the PM's here...instead of to each one

The WD Bars (round, or square/rectangular/etc) are all off center in reference to the TV Receiver/Shank/DrawBar...'BALL'

The trailer tongue/coupler mounts on that 'BALL' and swings side to side on that 'BALL'...meaning that is the pivot center

Most all WD Hitch systems (except for one...saw a pic of that, but don't note the name, where the WD Spring mechanism is centered between the tongue (between the 'V') has those bars offset from the hitch 'BALL' by some distance. Normally/generally about 2 inches on each side of the ball

When the trailer sways or swings off center line...the spring bar on one side will swing too, but at a different radius. One side will 'shorten' and the other side will 'lengthen'...ever more with greater off center swing/sway

That then has the 'anti-sway' mechanism come into play. They will resist that swing/sway via whatever way their designers decided

The farther away from the 'BALL' center line, the greater the push/pull...but at some distance, it will not allow tight maneuvering (purposely jack-knife).

Yes to that question about the trunnion's that use friction as their anti-sway mechanism...it is just like the old 'friction bar' and note that the tiny ball they mount to is offset from the 'BALL' center



There was a nifty spread sheet chart showing the push/pull, but that is no more with the demise of Photobucket's new "no longer allows posting to other sites' decision

[BenK]

IMHO....

All WD bars/trunnions are tensioned by the chains mounted on the trailer tongue. Think of standing on the trailer tongue and lifting up on a 5'-6' bar shoved into the TV reciever pin box. This will lift the TV's rear end and WD some of that weight to the TV's front axle...remove some of that weight from the TV's rear axle and since standing on the trailer tongue...come weight is transferred back onto the trailer tongue

Hitch Head tilt is to move the bars (round or trunnion) to point down more. That means the chains or whatever is used to tension them...more distance to bend them. Therefore more bar tension. Otherwise, the chains would NOT be able to pull them higher for more tension. Washers (regular round with a hole, serrated, etc) on some. Blue Ox is fixed via the casting

Trunnion bars slide on the saddle that is mounted on the trailer tongue. Some metal on metal, another has friction material at the mating (touching) area. This is the 'noise' that some complain about and some then advise to grease it to reduce/eliminate that noise...but that is how this setup works...friction to hold back the trunnion from sliding on that saddle to provide a push/pull against the trailer trying to move side to side (sway)

Cams will have both a saddle area on the bar end (a bend to form a 'V' saddle area that the cam nestles in). The cam is held in place by extensions that are mounted on the trailer tongue. This also makes noise as the cam is forced out of that saddle when the trailer sways side to side. One side will have the distance between the saddle and pivot of the bar reduce and other side lengthen. This is the push/pull against the trailer trying to move side to side (sway). The noise is the metal to metal between the saddle and cam. Some advise to grease this area, but that then makes it easier for the cam to come out of that saddle...reducing the amount of anti-sway

Blue Ox does this differently. Their bars are tapered from the hitch head (round) via a flattened and tapered to the end. It is bent way more than the others above. This will have one side straightened out when the trailer sways in one direction and the other side will have the bar bent even more. This provides a push/pull against the trailer trying to move side to side (sway)

Since no metal on metal sliding/rubbing/etc there is no noise generated. Just bending a spring bar more on one side and straightening the other side to then pull. This setup has very short chains, so the amount of travel is very small and the chain mechanism captures the chain to NOT allow the chain to move side to side

The Andersen works completely different

It's chains pull the trailer towards the TV's ball. The ball then hits the trailer coupler latch pawl and pulls the ball out of the coupler capture dome. The tapered friction material in the hitch 'head' has the special ball/shank (tapered shank) ride on that friction material. Any side to side movement has to overcome that friction material to ball/shank (that tapered shank is held in that tapered area via both the nut at the bottom and the weight of the tongue itself.

Since the Andersen chains pull the tongue into the TV ball...there is a compliant series of plastic bushings on the end of the chain. When the trailer sways side to side...one side compresses the stack of bushings and the other side releases the compression force...but IMHO, that stack is not long enough and the system bottoms out. Report of bushings breaking up have been reported...and/or the bracket on the tongue has also been reported to be pulled towards the TV when the side to side is high enough off center

HA/etc has spring bars too and works just like above...but no push/pull to control sway. There is a complicated mechanism that projects the sway pivot center forwards towards the TV to reduce sway. I've not looked at this setup in detail and might if ever consider getting one

My choice is Blue Ox, but have not purchased one. As no longer have a trailer of mine. Just borrow others and at 70 this year...not towing as much anymore.

[jerem0621]

Standard weight distribution can perform in a similar manner. Tilt the hitch head all the way out to the max number of washers/teeth and then adjust your spring bar tension. It may not handle as good since there is more free chain on the snap up brackets on a standard WD hitch than on a sway pro. But it will handle pretty nice.

This is the sway pro’s secret....fixed hitch head angle and shorter free chain... it’s not rocket surgery.

Thanks!

Jeremiah