I’ve got a 45’ Eagle towable manlift and bottom boom is leaking down.

[Puppypunter]

hey fellas just found this forum, I’ve had an extremely hard time finding a proper forum for hydraulics, and I’d appreciate your help.

I’ve got a 45’ Eagle towable and it’s just yiur simple boom lift, with manual outriggers and hardly any electronics at all. And a Honda engine running it and that’s it. Nice and simple it’s got a bottom boom and the top boom with left and right on the turret.

The problem is I think it’s a 1996 but the company was sold several times so I haven’t been able to locate any kind of manual however I did talk to a guy and he sent me 4 pages of info including the hydraulic schematic.

The bottom boom started leaking down slowly and when I use the bottom controls it goes up really fast but it still leaks down. When I use the top controls it’s always been really slow and it leaks Down as well.

I’m guessing it’s tge top controls because I’ve had them leaking for awhile slowly by the orings on the three spool valve. When u take it apart the spools look kinda worn, they aren’t real sharp and they just look alittle worn.

Do y’all think that sounds like a valve problem? Because the cylinders were repacked 4-5 years ago. The cylinders aren’t leaking anywhere.

What kind of valve is it that I need for the top 3 spool control (top and bottom boom, and left snd right.) are these cylinders double acting on the booms and what about the turret, it’s got a rotary motor on it ti turn it, would that be a different type? Here’s the schematic.

I don’t know what type of spool valve to order and I have no idea how many gallons per minute it should be either. Like I said the top controls are pretty darn slow, I realize the top controls are usually slower for safety but any insights into that would be appreciated.

It’s got a n 9hp Honda engine on it with a 5 gallon tank. Thanks again for any help I can get in this matter.

 

[oldnslo]

Most man lifts will have some form of load holding valve at the base of the cylinder. Can you see the base of the cylinder or is it buried in the frame?

 

[Puppypunter]

Do you mean on both boom cylinders or just the lower? I can see both and they look same.

Will the load valve have hoses running to it or would it be integrated into the cylinder?

It’s got a manual ball valve up by the bucket and there’s another on the turret. If you open either of these it’ll bleed down the bottom boom for emergencies. So you may be on to something.

Edit: wait a minute I think the top valve by the bucket bleeds the top cylinder, and then the one on the turret definitely bleeds the bottom boom.

 

[Puppypunter]

If I switch the hoses for the upper and lower boom on the upper control would that work to rule out tge spool valves?

Would I have to switch the hoses at the lower control as well to test tge upper controls?

 

[oldnslo]

The load holding valve can be integrated or hard plumbed to the cylinder.
Depending on style and or brand of valve it may have a cap that sticks out and inch or more or it could like a standard hex head plug.

I think you could just swap upper valve hoses and test.

 

[Dave M7040]

The parts diagram you posted describes the cylinders as have a valve in the base of the cylinder.
Likely it is some form of load check to prevent the cylinder from suddenly moving if a hose burst.
A small leak in this valve would allow the cylinder to lower.
I would remove the cylinder in question and take it to someone who services man lifts.
Dave M7040

 

[BeezFun]

If you extend each of the cylinders slightly, turn off the pump and manipulate the valves to relieve the pressure in the hoses. Now disconnect the hoses in the basket for both cylinders and see if either one leaks down. If they do, the load holding valve is bad and should be replaced. That's the only thing holding you in the air if a hose happens to burst.
Looking at the picture you posted, I would say that square block of steel on the end of the cylinder where the hoses attach has an internal pilot operated check valve. On my lift that block of steel is removable and can be replaced. Since your manufacturer is out of business you may have to get something aftermarket. A hydraulic shop can probably identify the cylinders and get you replacement parts for the check valve.
It's also possible your control valves are leaking but that should never allow the cylinders to leak down if the check valve is working properly.

 

[Puppypunter]

beezfun,
Ok I’ll try what you suggested however if I raise both cylinders and then turn the engine off won’t both cylinders go down when I manipulate the valves to relieve pressure? I notice on the schematic the ball valves I talked about earlier (see 16 for upper) it’s not showing the other one for tge bottom anywhere on the schematic. I’ll look into the valve y’all are talking about on the cylinder itself. Will there be a holding valve on both the upper and lower or just the lower? Thanks for tge help guys, I’m losing money everyday this thing is out.

 

[Puppypunter]

Oh and I noticed on the controls themselves there’s some kind of valve on both the upper controls snd bottom, im guessing it’s a flow control (gpm)? Could these be them?

Edit: nevermind, that couldn’t be them as y’all suggested that would defeat the purpose of if a hose broke it would come down ie it’s not hard plumbed to the cylinder

 

[Puppypunter]

Could the “solenoid valve” it shows on the schematic be it?