Reliability of fiver latch mechanism

powderman426 wrote:

jerem0621 wrote:
I don't want to hijack the other thread about the poor family whose fiver fell on their truck rails.

But his thread got me thinking about the reliability of the different jaws and I just wanted to ask a few questions... Maybe this will help me and some other newb in the future. This is excluding the gooseneck adapters. Just standard fifth wheels.

1) are there only three types of "jaws" to capture the kingpin?

• Single jaw
• double jaw
• slide bar?

2) is one more "locked in" than the other? The reason I ask that is because just from casual observance the double jaw wraps around the king pin and the joint is in the back, the single jaw has the joint to one side, the slide bar has no real joint and just a bar that slides behind the kingpin... The single jaw seems more secure to me... Is this incorrect?

3) the double jaw type, I read where the harder you pull the tighter the jaws close... Can someone expound on that... I don't understand how that works..

Thanks,

Jeremiah

If you look at one of the photos in the other post, it shows how the jaws are forward from the pivot point so when pressure is applied the jaws are being forced together instead of apart.

So I assume this is the photo you are referring to.
If you look at the arrow as the force of the pin, you see that because the pivot points are behind and out to the side of the pin the force of the pin forces the jaws shut.



The best proof I have of this is the 15 mile drive I took with the release handle UNLOCKED! The drive was a combination of freeway, and country roads speeds to 65 and stop and go, and crossing a couple of railroad crossings.
Understand that I always do a PULL TEST as soon as I back into the hitch, the twin jaw Reese doesn't need to be latched to be locked. I do connect with the release handle in with the jaws shut, with the handle free to slide the jaws open to let the pin in then snap shut, and will not open unless the release handle is pulled.

I truly believe that the issue with the Reese twin jaw is the amount that the handle comes up!! If you have an extended pin box and take a fairly sharp left turn, the pin box can strike the release handle, and could move far enough to cause a release.

That is why I made a simple modification to my release handle to eliminate that possibility.

BEFORE MODIFICATION!



AFTER MODIFICATION!