My lift keeps blowing off the return line at the end of the cylinder. One time it broke the fitting one time it split the line and this time it just blew the line out of the ptc. This is the 1/4" plastic line that runs back to the tank. Now the manual says that this line is to return fluid to the tank, but someone else told me that there should be no fluid in that line. Do I need to buy better connectors or do I need to get a new cylinder? Also the line blows on the way up not down.
Need some help with bendpak hd9
- Thread starter hanly2
- Start date
I have an Atlas 4 post lift which is probably the same setup as your Bendpak lift. The cylinder is single acting, fluid enters and exits the cylinder only on the end where the piston comes out. The port on the other end (where the small line is attached) is open to atmosphere and just allows air to enter and exit behind the piston as it retracts and extends. I asked Atlas about this small line that runs to the tank as it is not mentioned anywhere in the manual, not even in the parts breakdown. He said the reason it runs back to the tank is because if the cylinder sits without moving for a while flat spots can develop on the internal seal and you can get some blow by of fluid, which will get returned back to the tank via this line. As far as whether you need new parts or not I can't say, but it sounds like something may be preventing the air from freely escaping as the lift goes up (the cylinder retracts as the lift goes up so air would be exiting through this small line). I would first check to see if the fitting or line is plugged. Does the line connect to a fitting at the tank (that is the way mine is) or does it just go through a hole in the top of the tank?
stingry
Well-known member
the lift cylinders are one way cylinders, meaning that hydraulic pressure is only applied to the rod end of the piston on the way up. The cylinder side of the piston has air (and possibly some hydraulic fluid that may have leaked past the cylinder) in it and has to find its way out. Conversely, when gravity causes the lift to lower, air must find its way in to the cylinder. That is what small the line is for. I'm guessing that it is clogged somewhere and pressure builds up when raising the lift, causing it to blow out of the coupling.
Jman, you beat me to it!! I have the bendpak and the return line goes to a manifold under the control valve.
Jman, you beat me to it!! I have the bendpak and the return line goes to a manifold under the control valve.
Plastikosmd
Well-known member
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- Nov 17, 2016
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I would guess that if it is blowing off when actuating the lift then fluid under pressure is getting by the rod seal?
Is the compression fitting installed correctly? When it blew off, did you just reconnect it or did you cut 1/4 inch off the end and then reconnect? If it has a little compression disk that goes over the hose — I forget what they are called and can’t remember how I assembled my HD9 several years ago, did you reuse the old one or use a new one?
Does Bendpak specify a maximum air pressure and if so are you over it? I think there is one but maybe I am confused since I have bridge jacks as well.
Does Bendpak specify a maximum air pressure and if so are you over it? I think there is one but maybe I am confused since I have bridge jacks as well.
wssix99
Well-known member
BendPak has the parts and your manual should list some of the part numbers. How old is the lift.
I think the port you are looking at is the retract port:
For the lift, it's not really used for anything except during cable setup. For most situations, it should not be under high pressure. I expect that the fitting on your line is just bad.
I would start by putting in a new piece of black tubing and a new fitting on the cylinder.
I think the port you are looking at is the retract port:
For the lift, it's not really used for anything except during cable setup. For most situations, it should not be under high pressure. I expect that the fitting on your line is just bad.
I would start by putting in a new piece of black tubing and a new fitting on the cylinder.
with bendpak, they are not rebuildable, you just buy new
I think with this cylinder that port that you see that says retract flow is the port that the fluid goes in and out of, and the fluid is not supposed to go past the piston and seals, the extend flow port is only for atmosphere, and minimal fluid that made it past the seals. I think that the piston seals must be bad on my cylinder allowing too much fluid into that area.BendPak has the parts and your manual should list some of the part numbers. How old is the lift.
I think the port you are looking at is the retract port:
For the lift, it's not really used for anything except during cable setup. For most situations, it should not be under high pressure. I expect that the fitting on your line is just bad.
I would start by putting in a new piece of black tubing and a new fitting on the cylinder.
I would try to take the cylinder to a local hydraulic shop to get rebuilt. As long as it's not welded together at the factory it should be able to be resealed I would think. The local guy near me usually has most seals and orings, etc to reseal them without having to order a kit from a manufacturer. I've even taken them cylinders I've torn apart myself to get seals to redo myself. And worse case they've even made parts for really damaged cylinders. Always had good luck that way.
Joel
Joel
Wrench97
Well-known member
Cylinder needs to be rebuilt, the fluid is bypassing the seal in the cylinder.