Trail King Lowboy Trailer Hydraulics Leak Down

[Hunter013]

S/N: 11KJ05845MM095431

When the driver detaches the gooseneck from the trailer, after he pulls out and loads the machine, the gooseneck support arm slowly lowers the whole gooseneck which then, if you're not paying attention, will scrap on the road. There are no leaks anywhere. I'm assuming a valve is allowing hydro to seep by. Do I just take the valve out and clean it? Or rebuild it?

 

[crane operator]

Cylinder on the arm could be bypassing piston seals, and not leaking on the ground.

 

[Hunter013]

Is that more common/more likely than a bypassing valve? The arm does not leak down when driving around in the upright position, only when supporting the weight of the gooseneck after a few minutes.

 

[JaredV]

The one I pull has done the same thing for years. I have airbags so I air up when I pull away and then leave them aired up when I hook back up and the neck is at about the right height.

 

[crane operator]

If you pull the hose off the non pressure side of the cylinder, you should be able to tell what's going on. If oil comes out of the cylinder (after the initial oil that is on the back side), its bypassing the piston seal.

I would detach the neck, raise it clear up and hold the neck with a forklift/ excavator/ crane. Remove the hose off the non pressure side, with it held up with the other equipment. Then after the initial oil runs out, let down on the neck and see if oil comes out the cylinder. If it does, the piston seals are bad.

 

[crane operator]

If nothing comes out of the cylinder port you have off, while it's creeping down, your problem is in the valve/ elsewhere.

 

[cuttin edge]

Almost any float I have ever run does this over a long period of time. I have unhooked, and unloaded, and done a job. Then I return to the truck to re load, it has leaked down. One thing I find that guys do on an air ride truck, is drop the float, unhook and pull out before the air bags return to normal. Really bad if you are loaded. I always drop the suspension before I get out of the truck then un hook. Most times, I will re inflate the bags as I pull out. If you are on uneven ground, it raises you up high, then when I hook up, I drop the bags when I am close to the trailer. I see guys all the time that pull away only to have the eyes drag, and have to get out and raise up, and then lower to hook up again.

 

[Eastcoast8]

So… this is how I dealt with this after the support was accidentally overloaded…. First I switched the hoses…. This resulted in the support dropping while in the stored position…. This indicated to me that that the check valve in the cartridge had failed…. So I ordered a new cartridge…. Installed….condition corrected.
Some older Trailkings have the check valve on the cylinder…. This one did not….