I need help again! Trailer won't dump

I have never pulled anything other than a dry van, and the company I work for now is just acquiring its own equipment. I just changed the wet line hose on my company's tractor. We cannot get our trailer to dump now. Do I need to bleed the air out of the line first? The PTO is engaging and there was fluid in the line when we changed out the wing nut fitting, but not much. Someone please help, cause we don't know what we're doing!!

 

We got it figured out. One, the fitting was wrong, so the one way valve wasn't opening. Two, I wasn't using the PTO lever correctly. In the end, we got it going and felt like idiots after we figured it out. Next problem is getting a liner for the trailer. Any suggestions on vendors? What about Installing it yourself vs having it done "professionally"?

 

It is a single fitting, but yeah I got it figured out, thanks.

 

[QUOTE="semi" retired;4253267]All right! I've heard the thin plastic liners work good, shouldn't be that hard to install. Depends what you are hauling. Years ago, before liners, when we would haul big rocks, I'd put down a little sand first to cushion the rocks. Broken concrete or scrap steel did the most damage, don't forget the sides too.[/QUOTE]

It will basically be trash laden sawdust, but there could potentially be soil and rocks in the future. I'm thinking no less than 1/2 inch but debating 3/8. Just looking for more info and "real world" input since this is a very new field to me, not to mention to the company I'm with!