The Reese Dual Cam was part of the deal when we purchased our TT and we didn't know its true value until we tried it out.
Most of us that use the Reese Dual Cam understand the hitch's virtues (using friction between the cam & saddle) to lock the tow vehicle and trailer in a straight line. It occured to me that there is another dimension to the technology and its application that I have not considered or read about. It is the relationship between the operation of the Dual Cam and "wheel base".
Our Quest M-Van as a solo vehicle, with its Tow pkg and HD suspension tracks very well at highway speeds. When we bought a 1,500lb Coleman Pop up our highway straight line stability continued to be fine ( note no WD hitch or sway control was used or needed with the Coleman). Moving up to the TT brought a new and interesting revelation. Surprisingly at highway speed straight line driveability was even "more stable" with the TT in tow than the M-Van was by itself !?!.
A sports car like a Porsche for instance has a very short wheel base yet can travel at high rates of speed and be very stable. Conversely it has been said that when towing, a longer wheel based tow vehicle can, to some degree, feels more stable than a short wheel based vehicle combination.
We are aware that when cruising in a straight line the Reese dual cams lock in their saddles which in effect turns the vehicle/TT combination into "one", straight unit or entity. At this time, as long as the cams are locked into the saddles the rear wheels of the tow vehicle are only serving one purposes, primarly to support weight (on front wheel drive tow vehicles). With the cams locked in place the wheel base to consider now, as far as stability is concerned , is the wheel base distance from the front wheels of the tow vehicle to the wheels of the TT, not the back wheels of the Tow vehicle. The actual wheel base of the tow vehicle is at this point a very minimal factor! The wheel base of the total combination, the distance from the front wheels of the tow vehicle to the trailer wheels is actually the new relevant wheel base. Depending on the various combinations wheel base distance could vary anywhere from 250 to 350 inches or more. The theory would imply that by using a Reese Dual Cam system your "tow vehicles wheel base" in straight line driving has minimal effect on the combinations stability characteristics. This may help explain why many short wheel based tow vehicle have very good towing characteristics if in fact they are using a Reese Dual Cam hitch or equivilant. Of course other factors come into play. Tires, centre of gravity, sail influence ( front and side), etc.
Note that in a front wheel drive vehicle like our M-Van the whole combination is being pulled. To some degree the front wheel drive pulling action, working against the drag of the trailer is in effect firming (or straightening) up the unit as a whole. Think of this action as pulling on a rope that is secured at the opposite end. The more effort you use to pull on the rope the more taut and straight the rope becomes. In a rear wheel drive vehicle the rear wheels are pushing the vehicle and pulling the Trailer. This difference could influence to some degree the straight line stability with regards to the discussion.
Thought I would throw these theories out to the forum. Seems to make sense to me. Any thoughts?
Airstreams.... the best towing trailers on the planet!
With the cams locked in place the wheel base to consider now, as far as stability is concerned , is the wheel base distance from the front wheels of the tow vehicle to the wheels of the TT, not the back wheels of the Tow vehicle. The actual wheel base of the tow vehicle is at this point a very minimal factor! The wheel base of the total combination, the distance from the front wheels of the tow vehicle to the trailer wheels is actually the new relevant wheel base.
I wouldn't call this another dimension of the technology, but rather a different way of looking at it. As long as the cams are locked, an overpowered unicycle could pull it and remain stable. But that's like saying water is wet. The real issue is when the cams become unlocked. Now there is no rigid connection between TV and trailer, and the wheelbase and rear overhang of the TV become very important. If wheelbase is too short, you can get a tail-wagging-the-dog situation, a.k.a. sway.
I would agree. A theory of "virtual wheelbase" (for lack of knowing the technical term) starts to break down if the cams jump their saddle (turns, etc) and that the relative stability does appear to be different if the TV is rear wheel drive (along the general idea that it is easier to pull a rope than push it). Not sure how much RW drive would actually impact things, though. What about some of the AWD vehicles (pushing? pulling? both?)? I believe it fair to say once the cams are out of the saddle, any "virtual wheelbase" benefits are lost until the cams reseat themselves, regardless of drivetrain.
I would agree with most of this, but I question how much benefit in stability, you really gain from front wheel drive vs. rear wheel drive in this situation. If front wheel drive was really that advantageous for pulling, why are all the big rigs (18 wheeler types) rear wheel drive? I know thats going into a whole new ballgame, but still, rear wheel drive has been, and always will be the way, for heavy duty tow vehicles.
That, and I'm not convinced that the transaxle design of front wheel drive vehicles (transmission and differential all one piece), with the small little drive axles, is really that capable of handling heavy loads. IMO, that design is the reason why almost all minivans have a max towing capacity of 3500 lbs. I know, thats a whole separate debate, though.
Yes, the dual cam works great (I wouldnt have anything less), and you really can't beat it without spending thousands more for a hensley or pullrite. I think another benefit to the way it locks the trailer straight, would be when you have to do a panic stop. Dual cam will keep the trailer straight, and (hopefully) keep it from jackknifing on you, if you have to stop quickly. I don't know if a friction control would be able to do that, unless you had it really tight.
Will & Angela
2 children that love camping, Stephen & Allison
2003 Ford Excursion V10 4x4 ("No Taxpayers were harmed by the makers of this truck")
2003 Thor Citation 33M, Hensley Arrow hitch, Brakesmart Brake Control Our Rig
As another view of how the reese dual cam works:The cams will use the spring tension from the bars to force the tongue straight.Turning causes the bar to ride up the cam therfore increasing the the tension.The tension tries to force the bar off the cam straightening the tongue in relation to the tow vehicle.
dual cams lock? IMHO, that would be dangerous. Three axles locked in line become a handling nightmare.
What the cams do is to provide a force resisting pivoting around the coupler and ball favoring a center alignment and not having much effect at larger angles.
In other words, the dual cam serves somewhat like a shock absorber and serves much the same purpose except in the horizontal plane rather than the vertical.
A long wheel base is a matter of leverage. Another form of leverage is the Pullrite and Hensley (and 5th wheels and semi's) which use hitch geometry to reduce or eliminate the leverage between the coupler and ball point and the tow vehicle axles. This means that there is more control because the sideways forces do not have leverage to squiggle the tow vehicle.
Most other hitches just deal with controlling the rotation about the ball and coupler either using friction, a cam, or a shock absorber (Blue Ox), or some geometric tricks. The control is generally a damping force.
Fuzz1 - I am interested to know if the hitch you are refering to is the Reese Strait-Line Hitch 1200? I have been trying to get a comparison between that and the Hensley Arrow. The Reese is alot less money and seems to do the same thing. Would you share any information you may have.
Thanks
RVFred & Barb
2003 Flagstaff 25D
2000 Jeep Grand Cherokee Limited
I am interested to know if the hitch you are refering to is the Reese Strait-Line Hitch 1200? I have been trying to get a comparison between that and the Hensley Arrow. The Reese is alot less money and seems to do the same thing. Would you share any information you may have.
The Strait-Line Hitch is just a package containing a weight-distributing hitch and a dual-cam sway control. Although a fine setup, it most definitely does not work the same as a Hensley (I have both).
The dual-cam works to reduce sway by resisting it. The cams fit into saddles on the WD bars, and it takes a lot of force to move them. It works well, but a strong force can still induce sway.
With the Hensley, the hitch will break out-of-line only when a force is applied by the tow vehicle (e.g. when turning). Any force applied from the rearward side of the hitch will not cause it to break, making trailer-induced sway impossible.
Hi Fuzz- You obviously have given a great deal of thought to the straight-line dual cam basis for stability. However, it brings up a cause for a definite problem with shorter than desirable wheebase tow vehicles. Of course, when traveling in a straight line, the dual cam properly adjusted is a very stable entity. BUT, as soon as those cams are not in the saddle, they try to regain that stable position. If conditions are right, this may be the beginning of the fan tail motion we all dread. It is important to be sure the tow vehicle has a long enuf wheelbase - you are not always going to be traveling in a smooth straight line, especially in emergency manuvers.
Hank & Pat in New Hampshire wishing you-all safe journeys: Toyota Tundra (V-8, 4wd, 4.75L.,245 hp) Roadmaster Active Suspension; Nash 22H travel trailer, PullRite Hitch, Prodigy Brake Controller.
We would never tow a single axle trailer of significant weight again.
WHEN IN TROUBLE - WHEN IN DOUBT - RUN IN CIRCLES - SCREAM AND SHOUT!
In theory, you are correct. But in the real world, the cams never come out of their saddles at any speed beyond 2-3 mph, as you would almost never turn sharp enough for that to happen.
A right angle turn at 60 mph is going to roll the truck & trailer no matter what hitch you've got.
* This post was
edited 01/16/04 04:12pm by Brewster *
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