5th wheel locking jaws wouldn't close

That's what came to my mind. It can really be bad if you've been bobtail for any time.

 

Heres something I got in the habit of doing a long time ago...

Hook up, tug test, and then back up like youre gonna unhook. That way, when you get out to hook the airlines etc and you check the coupling, if you are high hooked or anything you can just release it without having to get back in the truck and back up again to take the pressure off the jaws.

I know it might sound lazy, but I believe in working smarter not harder.

 

I've had this happen and it took awhile to figure it out. The trl was just a little to high and as the jaws tried to close around the pin they hit the edge ( the big thick part) and don't lock ( if it did lock then ya got a real loose 5th wheel) No other way out of other than cranking the trl down a little.

 

Had that happen yesterday, bumped the pin a few times, wouldn't latch. Pulled out and found that the jaw was unlatched, but still in the way. I used a hook that normally pulls a fifth wheel release, to move it back where it should be.

 

Also look under the front of the fifth wheel. That spring can break or be damaged.
Had it happen on my 2011 truck.

 

You shouldn't ever have to crank a trailer up when its loaded, get some HARDWOOD blocks of varying thickness and keep them in your truck, when a trailer is too low, release your air suspension and back under the trailer a bit, place a wood block between the frame and trailer and inflate your air bags, crank your landing gear down and repeat if necessary.

 

I have this problem pretty regular, mostly because too many drivers drop trailers too high. When it happens to me the trailer is too high, not like your episode, the kingpin jams into the top of the jaws at a wrong angle but the jaws will not latch. The jaws just move to the closed position, but they do not latch. If you crawl under the trailer and look at the 5th wheel jaws everything looks normal, but as you said when you tug on the trailer it just slides right out. Most times, with me, the 5th wheel release handle also moves to the "ready to get on the road" position.

For years I got someone to help me. One of us pulled on the 5th wheel release handle and one of us used my pin puller to pull the jaws open.

There is an easier way. Pull forward away from trailer enough so 5th wheel tilts with front of it fully up and back fully down. Now, pull and hold the 5th wheel handle as far as it will go for several seconds, maybe 5 seconds just to be sure. In every case so far the 5th wheel jaws will slowly move to the full open position and reset. Now when you back under and the kingpin slides into the jaws they will now latch.

You may not need to start with the 5th wheel tilted. The "pull and hold" may work fine whatever position the 5th wheel is in.

I hope this works for you. I was thoroughly impressed when the mechanic showed me.

For anyone reading this: if the legs on your trailer landing gear are touching the ground before you drop the trailer, and the trailer is being dropped on level ground, YOU ARE DROPPING IT TOO ###### HIGH. I don't care if you dump the airbags or have no airbags. CDL school mistakenly teaches rookies to crank the gear down to the ground and then crank in a few (1-100) more turns for good luck. That is wrong and it really screws the next driver to pick up that trailer.

With our fleet it's best if the Volvo drivers leave the landing gear 5 turns of the landing gear off of the ground (high speed crank position) and it's best if Freightliner drivers leave gear 6-8 turns off of the ground. We routinely have rookie and experienced drivers dropping trailers so high the bottom of the kingpin doesn't even touch the tilted front-end of the 5th wheel plate. It really sucks to get the kingpin stuck on the front edge of the 5th wheel. We've had one driver drop a trailer in the road because he high hooked a trailer.

It doesn't matter how many years or million miles you have OTR until you are told or shown what I am talking about you may still be doing it wrong. The exception is dropping trailers into sunken dock doors or sloping ground. Often you can only leave the gear feet one or 2 turns off of the ground.

The landing gear should only touch the ground AFTER you pull away if the trailer is on level ground. Just because you drop a trailer and flee the scene doesn't mean you aren't screwing the next driver with a high trailer and someone's experience with a moron dropping a trailer too low doesn't mean it's OK to leave one too high.

Ideally, you want the bottom of the trailer after you drop it to be higher than your drive tires but lower than the 5th wheel so that a tractor hooking up will raise all of the weight of the trailer. If you do it the way I describe you can raise and lower trailer gear with one finger and no more effort than it takes to wave your hand in a circle.

 

I had that happen up in northern PA last friday night. I ended up slamming the hell out of the trailer to get it to lock.

 

We arent all blessed with the luxuries of an air bag dump or even an air suspension.