self bleeding cylinder, but how?

[samsonite]

I was wondering how the air will escape from my boom and bucket cylinders after all the work I've been doing. Seems to me the hydraulics are like a brake system, either you bleed it or suck the air out.

 

[Tazza]

It mixes in all the oil to the cylinder, as it goes in and out, some will return to the tank, this is where the air goes. It foams up all the oil, not just a pocket in the brake fluid
I think the piston stroke is quite a bit more than a car brake system, that's why it bleeds, unlike a brake system does.

 

[jerry]

On a brake system almost all the fluid never leaves the line , just enough to push the wheel cyl and when not braking that little bit backs up into the master cyl. On your hyd cyl its all fresh oil pumped in to extend and when you retract it that oil goes back to the reservoir as new oil is coming in the other side of the piston. So there is a flow rather than static fluid like a brake. Like Tazza said the outgoing oil carries the air along with it to the tank.

 

[samsonite]

On a brake system almost all the fluid never leaves the line , just enough to push the wheel cyl and when not braking that little bit backs up into the master cyl. On your hyd cyl its all fresh oil pumped in to extend and when you retract it that oil goes back to the reservoir as new oil is coming in the other side of the piston. So there is a flow rather than static fluid like a brake. Like Tazza said the outgoing oil carries the air along with it to the tank.

Thanks for the help guys, I understand what you guys are saying. The oil will get mixed with the air upon usage, and some of it will be carried back to the controll valve. I just have a hard time beliving all the oil/air ever gets back to the spool. The hoses are 10 to 15 feet long on the bucket circuit. I probably am being too picky on this. I blew a hose awhile ago and it seems like the air has never fully gotten out of the bucket circuit. I checked my suction hose clamps and tighened them all a little, but they were allready pretty tight. The rubber T assembly looked good, no rubbing. I've got to have a problem somewhere that I'm missing.

 

[jerry]

Thanks for the help guys, I understand what you guys are saying. The oil will get mixed with the air upon usage, and some of it will be carried back to the controll valve. I just have a hard time beliving all the oil/air ever gets back to the spool. The hoses are 10 to 15 feet long on the bucket circuit. I probably am being too picky on this. I blew a hose awhile ago and it seems like the air has never fully gotten out of the bucket circuit. I checked my suction hose clamps and tighened them all a little, but they were allready pretty tight. The rubber T assembly looked good, no rubbing. I've got to have a problem somewhere that I'm missing.

I see what you are saying, the oil in the hose between the valve and the cyl doesn't all go back to the tank , it just stays in the line till you extend the cyl and add new oil to it. Never have had much trouble with air though.