The Holland/Binkley fifth-wheel I have is normally used in inverted mode on the trailer, but is sometimes used in "normal" orientation on the tow vehicle. My F-350 was already fitted with a Binkley telescoping king-pin so I bought a Binkley fifth-wheel to match. I did a lot of reading on the internet and learned what options I had.

Big truck fifth-wheels mostly have a single pivot axis that allows the trailer and tractor combination to bend when negotiating rises and dips. When negotiating a road-side dip while turning, the springs try to compensate, the frames twist, and the tires of the trailer even lift off the ground if it is unloaded. I have seen this, so I assume many of you have as well.

On a very small percentage of big rigs, the fifth-wheel is an "oscillating" type. This means that it has a second pivot axis that allows the trailer to sway independently of the truck. The Holland site explained that the application for this was on tankers where the tank is the frame and too much torsion leads to problems. Maybe some of you have also seen the evidence of this problem - diagonal wrinkles in the tank. Most tankers are highway only and I assume tanker drivers (& many others) are careful not to take too sharp a dip or rise while turning. I have yet to see a full-size oscillating-type fifth-wheel other than in pictures.

The previous owner of my F-350 had done a lot of fifth-wheel towing and felt strongly about the benefits of having the trailer & truck locked together, with regard to sway. This makes a lot of sense because the whole set of springs on both vehicles are resisting sway and you do not have two independent sway frequencies that could cause problems.

I initially ordered the "plain" Binkley, but the dealer said I could have the oscillating model cheaper if I did not mind doing a little modification. It turned out that there was a minor (< 1/64") mis-alignment between a hole and its reinforcing plate from poor jigging during welding. Literally a few licks with a file was all that was needed. Anyway I have an oscillating-type fifth-wheel. On my 15 acres I do not have a dead flat turn-around area, so I think that the extra axis will ease my nerves during maneuvering on my property. I do plan on making a system to easily lock out the extra axis when I am going down the interstate, especially with a tall load and high cross-winds.

One of my questions about fifth-wheel stability is to find out what everyone else knows about this. You goose-neck guys that have a ball & socket type coupler have the equivalent of an oscillating-type fifth-wheel - do you have more sway problems than a "rigid" fifth-wheel?