Tractor will not detach from trailer

if its air, then you got to pull nob,with brakes set. it wont release fifth wheel with the brake in

 

What do you mean "it won't come loose"? You mean the handle won't pull out and stay out? or the handle is coming out and staying out, but you still can't pull away from the trailer?

Is this a new problem or has it been acting up for a while?

Is this a level pad and the tractor and trailer or on an even plane?

 

Oh. Set the trailer brakes, then release the tractor brakes, then "nudge back" in reverse ever so slightly [against the 5th wheel king pin], then set the tractor brakes. You should feel a slight "bump" as it moves within the small tolerance gap. The 5th wheel unlatch handle should then pull out much easier.

The jaws wrap around the back side of the king pin, you're trying to assure there is not a bind between the back of the king pin and the front of the jaws. Some 5th wheels are more susceptible to this problem than others, depending on how well they are adjusted and in spec.

 

Once I had a lever you had to push forward and then pull out to get it to release. I got a mechanic to release it, and he finally figured it out for me. I thought I had tried that, but apparently not.

 

In the future try to have the 5th wheel at the right height in regard to the kingpin. Most of the time the way those 5th wheels are you have some space to play with. However if the kingpin hits the 5th wheel high it can over time tear the latching mechanism up.

 

Just leave it hooked up.

 

Like the one guy said set the trailer brakes and reverse a bit like a backwards tug test. Mine does that all the time.

 

take her for a ride around the block. shell come off there